The document discusses an electrochemical sensor for determining catechol using a screen printed graphite electrode. Cyclic voltammetry was used to study the electrochemical behavior of catechol, which showed reversible one-electron oxidation and reduction peaks. Square wave voltammetry allowed for direct determination of catechol concentration, showing a linear range from 1x10-6 to 1x10-4 M. Interference from ascorbic acid was examined. The method was applied to determine catechol concentration in water samples.
Electrochemical behaviorof carbon paste electrode modified with Carbon Nanofi...IJERA Editor
The electrochemical behavior of carbon paste electrode modified with carbon nanofibers has been studied using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scaning electron microscopy. The response of modified electrodein ferroferricyanidesolutionshows reversible behavior and significant increment in current value compared to the bare CPE indicating that CNFs act as efficient electron mediator to catalyze reactions at the surface. The modified electrode has been used to study the electrochemical response of bisphenol Ausing different electrochemical techniques such as cyclic voltammetry, linear sweep voltammetry, differential pulse voltammetry and square wave voltammetry. The oxidation peak of BPA was observed at about 0.53 V in phosphate buffer solution at pH 6.7. The oxidation peak current of BPA varied linearly with concentration over a wide range of 5µmol L-1 to 400 µmol L-1 and the detection limit of this method was found to be 0.55 µmol L
Electrochemical properties of myoglobin deposited on multi walled carbon nano...Expand_Lives
We report the direct electrochemical and electrocatalytic properties of myoglobin (MB) on a multi-walled
carbon nanotube/ciprofloxacin (MWCNT/CF) film-modified electrode. A highly homogeneous MWCNT
thin-film was prepared on an electrode surface using ciprofloxacin (CF) as a dispersing agent. MB was
then electrochemically deposited onto the MWCNT/CF-modified electrode. The MB/MWCNT/CF film was
characterized by scanning electron microscopy and UV–visible spectroscopy (UV–vis). UV–vis spectra
confirmed that MB retained its original state on the MWCNT/CF film. Direct electrochemical properties of MB on the MWCNT/CF film were investigated by cyclic voltammetry. The formal potential and
electron transfer rate constant were evaluated in pH 7.2 buffer solution as−0.327 V and 300 s
−1
, respectively. In addition, the MB/MWCNT/CF-modified electrode showed excellent electrocatalytic properties
for the reduction of hydrogen peroxide (H2O2). The MB/MWCNT/CF-modified electrode was used for the
detection of H2O2at concentrations from 1×10
−6
Mto7×10
−4
M in pH 7.2 buffer solution. Overall, the
MB/MWCNT/CF-modified electrode was very stable and has potential for development as a H2O2sensor.
Photoelectrochemical characterization of titania photoanodes fabricated using...Arkansas State University
Design and fabrication of new electrodes for photo-electrolysis using a material that is photo-active, stable, corrosion resistant, and cost effective.
IrO2 as an anodic electrocatalyst for the oxygen evolution reaction (OER) in solid polymer electrolyte (SPE)
electrolysers was synthesised by adapting the Adams fusion method. Optimisation of the IrO2 electrocatalyst was achieved
by varying the synthesis duration (0.5 – 4 hours) and temperature (250 - 500°C). The physical properties of the
electrocatalysts were characterised by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and
x-ray diffraction (XRD). Electrochemical characterisation of the electrocatalysts toward the OER was evaluated by
chronoamperometry (CA). CA analysis revealed the best electrocatalytic activity towards the OER for IrO2 synthesised
for 2 hours at 350oC which displayed a better electrocatalytic activity than the commercial IrO2 electrocatalyst used in this
study. XRD and TEM analyses revealed an increase in crystallinity and average particle size with increasing synthesis
duration and temperature which accounted for the decreasing electrocatalytic activity. At 250°C the formation of an active
IrO2 electrocatalyst was not favoured.
This document describes research on a new chemically modified electrode incorporating zeolite ZSM-5 for determining the drug piroxicam. Specifically:
- A carbon ceramic electrode was modified by incorporating zeolite ZSM-5 using a sol-gel method, creating a carbon ceramic zeolite modified electrode (CCZME).
- The voltammetric behavior of piroxicam at the CCZME was investigated, showing the electrode exhibited catalytic activity toward electrooxidation of piroxicam.
- Under optimized conditions, the CCZME allowed determination of piroxicam using differential pulse voltammetry and hydrodynamic amperometry, with good linear ranges and detection limits.
Photochemical study of micelles in photogalvanic cell for solar energy converIAEME Publication
- The document describes a study of a photogalvanic cell containing Rhodamine 6G, EDTA, and sodium lauryl sulfate (NaLS) for solar energy conversion and storage.
- Key results include a maximum photopotential of 905.0 mV, photocurrent of 450.0 μA, conversion efficiency of 1.26%, fill factor of 0.2516, and storage capacity of 170 minutes under illumination for 140 minutes.
- The effects of varying the concentrations of dye, reductant, and micelles were investigated, finding optimal values that produced the highest electrical outputs from the cell. Other parameters such as pH, diffusion length, and electrode area were also examined.
The document describes a study that deposited electrochemically reduced graphene oxide (ERGO) on aluminium copper (AlCu) substrates using electrodeposition at different voltage windows and cycles to produce humidity sensors. ERGO was deposited at voltage windows of 0.3V to -0.2V and 0.3V to -0.6V, with 1, 2, or 3 cycles within each window. Raman spectroscopy showed the deposited ERGO had characteristic D, G, and 2D bands. Humidity sensing tests found the sample deposited at 0.3V to -0.6V for 2 cycles had the highest sensitivity of 67.63% due to its thicker nanoporous structure providing a larger surface area to absorb water
2021 influence of basic carbon additives on the electrochemical performance ...Ary Assuncao
This study investigates the effect of carbon surface basicity on the electrochemical performance and dynamic charge acceptance of lead-carbon batteries. Five activated carbons with different pH values ranging from 9.5 to 11.1 were prepared by ammonia and hydrogen gas treatments. Cyclic voltammetry showed that the hydrogen evolution reaction activity increased with higher carbon surface basicity. Testing of lead-carbon electrodes found a correlation between carbon pH and dynamic charge acceptance, with higher pH carbons showing improved charge currents and final dynamic charge acceptance. The carbon content also affected charge currents during simulated microcycles, demonstrating that surface chemistry and amount of carbon additive both influence the electrochemical properties and performance of lead-carbon batteries.
Electrochemical behaviorof carbon paste electrode modified with Carbon Nanofi...IJERA Editor
The electrochemical behavior of carbon paste electrode modified with carbon nanofibers has been studied using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scaning electron microscopy. The response of modified electrodein ferroferricyanidesolutionshows reversible behavior and significant increment in current value compared to the bare CPE indicating that CNFs act as efficient electron mediator to catalyze reactions at the surface. The modified electrode has been used to study the electrochemical response of bisphenol Ausing different electrochemical techniques such as cyclic voltammetry, linear sweep voltammetry, differential pulse voltammetry and square wave voltammetry. The oxidation peak of BPA was observed at about 0.53 V in phosphate buffer solution at pH 6.7. The oxidation peak current of BPA varied linearly with concentration over a wide range of 5µmol L-1 to 400 µmol L-1 and the detection limit of this method was found to be 0.55 µmol L
Electrochemical properties of myoglobin deposited on multi walled carbon nano...Expand_Lives
We report the direct electrochemical and electrocatalytic properties of myoglobin (MB) on a multi-walled
carbon nanotube/ciprofloxacin (MWCNT/CF) film-modified electrode. A highly homogeneous MWCNT
thin-film was prepared on an electrode surface using ciprofloxacin (CF) as a dispersing agent. MB was
then electrochemically deposited onto the MWCNT/CF-modified electrode. The MB/MWCNT/CF film was
characterized by scanning electron microscopy and UV–visible spectroscopy (UV–vis). UV–vis spectra
confirmed that MB retained its original state on the MWCNT/CF film. Direct electrochemical properties of MB on the MWCNT/CF film were investigated by cyclic voltammetry. The formal potential and
electron transfer rate constant were evaluated in pH 7.2 buffer solution as−0.327 V and 300 s
−1
, respectively. In addition, the MB/MWCNT/CF-modified electrode showed excellent electrocatalytic properties
for the reduction of hydrogen peroxide (H2O2). The MB/MWCNT/CF-modified electrode was used for the
detection of H2O2at concentrations from 1×10
−6
Mto7×10
−4
M in pH 7.2 buffer solution. Overall, the
MB/MWCNT/CF-modified electrode was very stable and has potential for development as a H2O2sensor.
Photoelectrochemical characterization of titania photoanodes fabricated using...Arkansas State University
Design and fabrication of new electrodes for photo-electrolysis using a material that is photo-active, stable, corrosion resistant, and cost effective.
IrO2 as an anodic electrocatalyst for the oxygen evolution reaction (OER) in solid polymer electrolyte (SPE)
electrolysers was synthesised by adapting the Adams fusion method. Optimisation of the IrO2 electrocatalyst was achieved
by varying the synthesis duration (0.5 – 4 hours) and temperature (250 - 500°C). The physical properties of the
electrocatalysts were characterised by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and
x-ray diffraction (XRD). Electrochemical characterisation of the electrocatalysts toward the OER was evaluated by
chronoamperometry (CA). CA analysis revealed the best electrocatalytic activity towards the OER for IrO2 synthesised
for 2 hours at 350oC which displayed a better electrocatalytic activity than the commercial IrO2 electrocatalyst used in this
study. XRD and TEM analyses revealed an increase in crystallinity and average particle size with increasing synthesis
duration and temperature which accounted for the decreasing electrocatalytic activity. At 250°C the formation of an active
IrO2 electrocatalyst was not favoured.
This document describes research on a new chemically modified electrode incorporating zeolite ZSM-5 for determining the drug piroxicam. Specifically:
- A carbon ceramic electrode was modified by incorporating zeolite ZSM-5 using a sol-gel method, creating a carbon ceramic zeolite modified electrode (CCZME).
- The voltammetric behavior of piroxicam at the CCZME was investigated, showing the electrode exhibited catalytic activity toward electrooxidation of piroxicam.
- Under optimized conditions, the CCZME allowed determination of piroxicam using differential pulse voltammetry and hydrodynamic amperometry, with good linear ranges and detection limits.
Photochemical study of micelles in photogalvanic cell for solar energy converIAEME Publication
- The document describes a study of a photogalvanic cell containing Rhodamine 6G, EDTA, and sodium lauryl sulfate (NaLS) for solar energy conversion and storage.
- Key results include a maximum photopotential of 905.0 mV, photocurrent of 450.0 μA, conversion efficiency of 1.26%, fill factor of 0.2516, and storage capacity of 170 minutes under illumination for 140 minutes.
- The effects of varying the concentrations of dye, reductant, and micelles were investigated, finding optimal values that produced the highest electrical outputs from the cell. Other parameters such as pH, diffusion length, and electrode area were also examined.
The document describes a study that deposited electrochemically reduced graphene oxide (ERGO) on aluminium copper (AlCu) substrates using electrodeposition at different voltage windows and cycles to produce humidity sensors. ERGO was deposited at voltage windows of 0.3V to -0.2V and 0.3V to -0.6V, with 1, 2, or 3 cycles within each window. Raman spectroscopy showed the deposited ERGO had characteristic D, G, and 2D bands. Humidity sensing tests found the sample deposited at 0.3V to -0.6V for 2 cycles had the highest sensitivity of 67.63% due to its thicker nanoporous structure providing a larger surface area to absorb water
2021 influence of basic carbon additives on the electrochemical performance ...Ary Assuncao
This study investigates the effect of carbon surface basicity on the electrochemical performance and dynamic charge acceptance of lead-carbon batteries. Five activated carbons with different pH values ranging from 9.5 to 11.1 were prepared by ammonia and hydrogen gas treatments. Cyclic voltammetry showed that the hydrogen evolution reaction activity increased with higher carbon surface basicity. Testing of lead-carbon electrodes found a correlation between carbon pH and dynamic charge acceptance, with higher pH carbons showing improved charge currents and final dynamic charge acceptance. The carbon content also affected charge currents during simulated microcycles, demonstrating that surface chemistry and amount of carbon additive both influence the electrochemical properties and performance of lead-carbon batteries.
The document summarizes research on the electrochemical deposition of lead dioxide nanostructured thin films. Key findings include:
- Lead dioxide nanostructures were successfully deposited on gold-coated substrates by anodic electrochemical deposition using nitric acid and lead chloride as reactants. The morphology was influenced by deposition parameters like potential, temperature, and pH.
- Deposition at higher temperatures (60°C vs room temperature) resulted in faster growth rates and denser nanostructures, as seen by SEM images.
- Both anodic and cathodic deposition were studied. Cathodic deposition allowed formation of different lead oxide phases depending on conditions, while anodic deposition selectively formed PbO2.
- The work provides a
Surface Activation of C-sp3 in Boron-Doped Diamond ElectrodeAlejandro Medel
Abstract C-sp2 (graphite) impurities are undesirable in synthetic diamond electrodes (C-sp3), because they can affect the electrochemical response. In this work, we demonstrate that Csp3 surfaces can be activated successfully by applying an anodic current density corresponding to sufficiently high potential where the hydroxyl radicals (●OH) are generated. The
effectiveness of this activation process was verified by Raman spectroscopy, X-ray diffraction, scanning electron microscopy, and cyclic voltammetry.
This document summarizes a study that characterized graphite anodes from lithium-ion battery cells after fast charging. Multi-scale characterization techniques revealed increased disorder near the edges of graphite particles in anodes that experienced lithium plating during fast charging. Specifically, transmission electron microscopy showed wavy graphite fringes and higher d-spacings near particle edges, indicating greater lattice disorder extending 20 nm into the bulk. This disorder hinders lithium ion intercalation and favors lithium plating during repeated fast charging. Scanning electron microscopy also showed fast-charged anodes were thicker due to accumulated electrolyte reduction products in pores.
International Refereed Journal of Engineering and Science (IRJES)irjes
International Refereed Journal of Engineering and Science (IRJES) is a leading international journal for publication of new ideas, the state of the art research results and fundamental advances in all aspects of Engineering and Science. IRJES is a open access, peer reviewed international journal with a primary objective to provide the academic community and industry for the submission of half of original research and applications.
Synthesis, Characterization and Electro analytical Applications of Nitrogen D...IRJET Journal
This document summarizes research on synthesizing and characterizing nitrogen-doped ordered mesoporous carbon (CMK-3) for use as a modified electrode in electrochemical analysis. CMK-3 was synthesized using honey as a natural carbon source and SBA-15 mesoporous silica as a template. Characterization with XRD, BET, SEM and TEM showed the carbon replicated the hexagonal structure of SBA-15 and had a surface area of 587.8 m2/g. Cyclic voltammetry demonstrated the CMK-3 modified electrode could selectively determine dopamine, L-cysteine, ascorbic acid and paracetamol through well-defined oxidative/reductive peaks
Synthesis and optimisation of ir o2 electrocatalysts by adams fusion method f...materials87
The document describes the synthesis and optimization of iridium dioxide (IrO2) electrocatalysts for oxygen evolution reaction (OER) in solid polymer electrolyte electrolyzers. IrO2 was synthesized using an Adams fusion method by varying synthesis duration (0.5-4 hours) and temperature (250-500°C). Characterization showed that increasing synthesis time and temperature improved crystallinity and increased particle size. Electrochemical testing revealed that IrO2 synthesized for 2 hours at 350°C exhibited the best electrocatalytic activity toward OER compared to a commercial IrO2 catalyst. Higher temperatures and longer times favored larger, more crystalline particles but decreased surface area and activity.
Synthesis and optimisation of ir o2 electrocatalysts by adams fusion method f...sudesh789
This document discusses the synthesis and optimization of iridium dioxide (IrO2) electrocatalysts for use in solid polymer electrolyte electrolyzers through an adaptation of the Adams fusion method. The synthesis duration and temperature were varied to determine their effect on the physical and electrochemical properties of the IrO2 catalysts. X-ray diffraction analysis showed that increasing the synthesis duration and temperature increased the crystallinity and particle size of the IrO2. Chronoamperometry testing revealed that a synthesis of 2 hours at 350°C produced an IrO2 catalyst with better electrocatalytic activity for oxygen evolution than a commercial IrO2 catalyst.
Synthesis, characterisation and evaluation of ir o2 based binary metal oxide ...suresh800
This document describes the synthesis, characterization, and evaluation of various binary metal oxide electrocatalysts for the oxygen evolution reaction in solid polymer electrolyte electrolyzers. Specifically, IrO2, IrxRu1-xO2, IrxSnx-1O2 and IrxTax-1O2 (where 1 ≥ x ≥ 0.7) were synthesized using the Adams fusion method, and then characterized using XRD, SEM, TEM, and electrochemical techniques. XRD analysis showed that solid solutions were formed when RuO2, SnO2, or Ta2O5 were added to IrO2. TEM analysis revealed nanosize particles for all synthesized metal oxides. Electrochemical
This document summarizes the electrochemical synthesis and corrosion inhibiting properties of a poly N-methyl aniline coating doped with di-N-propyl malonic acid on stainless steel. Cyclic voltammetry was used to polymerize N-methyl aniline in a solution containing di-N-propyl malonic acid on a stainless steel electrode. An adherent red polymer film was obtained. Electrochemical impedance spectroscopy and potentiodynamic polarization techniques showed that this polymer coating provided excellent corrosion protection of stainless steel in 0.5M sulfuric acid solution, with inhibition efficiencies above 99% as indicated by large increases in charge transfer resistance and decreases in corrosion current density compared to uncoated stainless steel.
This study examined the surface area that contributes to current density in microbial electrochemical systems. Experiments used a graphite plate working electrode and Geobacter subterraneus to form biofilms on both sides. Chronoamperometry showed biofilms formed on both sides. Cyclic voltammetry identified a direct electron transfer mechanism with a defined potential. Confocal laser scanning microscopy and modeling found the biofilms were uniformly thick at ~75 μm and contributed equally to the current density of ~2.5 A/m2, demonstrating both sides of a planar electrode can transfer electrons regardless of orientation.
The document discusses microbial fuel cells (MFCs) as an alternative for producing clean electricity. MFCs take advantage of microbial metabolism to generate electricity directly. They consist of an anode where microorganisms oxidize organic substrates and release electrons, and a cathode where oxygen is reduced. Microbes can transfer electrons to the anode through either direct contact or electron shuttles like cytochromes. While power outputs from MFCs have increased significantly in recent years, further improvements are still needed before they can compete commercially with other energy technologies. Understanding microbial electron transfer mechanisms and ecology is crucial to optimizing MFCs.
A closed loop ammonium salt system for recovery of high-purity lead tetroxide...Ary Assuncao
This document describes a closed-loop hydrometallurgical process for recovering high-purity lead tetroxide from spent lead-acid battery paste. The process involves leaching the paste with a mixed solution of ammonium acetate, acetic acid, and hydrogen peroxide. The leachate is then reacted with ammonium carbonate to precipitate lead carbonate. Impurities are removed during leaching and precipitation. The regenerated leachate is recycled for the next leaching. Lead carbonate is calcined to produce lead tetroxide with low impurity levels meeting industry standards. This process allows for reagent recirculation and production of a high value lead recovery product.
Synthesis of Spinel based Catalysts by Wet chemical methods for Colour Remova...PranavkumarRana
The study aimed at color removal and COD degradation of
synthetic wastewater of methylene blue dye via photocatalysis using various spinel catalysts
prepared by different methods. The methylene blue dye with strong azo bond with structure
made up of autochrome and chromophore. The Azo dyes are widely used in textile, paper and
leather industries. The present study is essentially related to the degradation of selected
methylene blue and dye from synthetic dye wastewater however it has been extended to actual
industrial effluents. In order to control wastewater pollution due to dyes the UV-Photocatalytic
degradation technology has been carried out by some researchers using spinel catalysts. Spinel
catalysts are oxides with general formula AB2O4 where A and B are the rare earth, A has
octahedral site and B has tetrahedral site. alkaline earth, alkali metals and transition metal
cations which are expected to be able to overcome the limitations of semiconductors as
photocatalysts.
This document summarizes research on electrodepositing silver nanoparticles onto carbon sphere surfaces using a pulse current. Key findings include:
1) Silver nanoparticles were successfully electrodeposited with a size of 100-400nm after 2 minutes using a pulse current.
2) Deposition occurred on accessible carbon surface sites, forming a monolayer of scattered nanoparticles. Continued deposition led to larger particles and multilayers.
3) Pulse current helped manage monolayer deposition compared to direct current, controlling particle size and number of layers.
This document summarizes the synthesis, characterization, and evaluation of various IrO2-based binary metal oxide electrocatalysts for the oxygen evolution reaction. IrO2, IrxRu1-xO2, IrxSnx-1O2 and IrxTax-1O2 (where x is between 1 and 0.7) were synthesized via an adapted Adams fusion method. X-ray diffraction and electron microscopy showed the materials formed nanocrystalline solid solutions. Electrochemical testing found that adding RuO2, SnO2, or Ta2O5 to IrO2 improved its catalytic performance for oxygen evolution. Specifically, Ir0.7Ru0.3O2 exhibited the best
A high-capacity lithium-air battery with Pd modified carbon nanotube sponge c...liaoss
1) The document describes a lithium-air battery with a free-standing, highly porous carbon nanotube (CNT) sponge cathode modified with palladium (Pd) nanoparticles.
2) The Pd-CNT sponge cathode provides a continuous pathway for lithium ions, oxygen, and electrons to flow, enabling high capacity discharge reactions in the battery.
3) The battery utilizes an ionic liquid electrolyte and a lithium super ionic conductor (LiSICON) ceramic plate to protect the lithium metal anode. This allows the battery to operate stably in open air conditions with capacities as high as 9092 mAh/g.
PIERRA M., TRABLY E., GODON J.J., BERNET N. Successful enrichment procedure for electroactive biofilm formation from environmental sample. MFC4 / 4th International Microbial Fuel Cell Conference, September 1st - 4th, 2013, Cairns, Queensland, AUSTRALIA
This chapter describes the fabrication of a zirconia nanoparticle-decorated reduced graphene oxide (ZrO2/rGO) nanocomposite for an electrochemical sensor to detect the anticancer drug regorafenib. Characterization using XRD, FT-IR, XPS, TEM and EDX confirmed the successful synthesis of ZrO2 nanoparticles on rGO. Electrochemical tests using cyclic voltammetry and differential pulse voltammetry showed the ZrO2/rGO modified electrode has excellent electrocatalytic activity for regorafenib oxidation, with a wide linear detection range of 11-343 nM and a low detection limit of 3.7 nM. The sensor also demonstrated good
This document presents a study evaluating the use of a gold screen-printed electrode as an electrochemical sensor for the rapid determination of levodopa. Levodopa is the primary drug used to treat Parkinson's disease. The study found that using the electrooxidation of levodopa at a potential of +0.63 V in an acetate buffer at pH 3.0, the sensor provided a linear calibration curve from 9.9 × 10−5 to 1.2 × 10−3 mol L−1 with a detection limit of 6.8 × 10−5 mol L−1. Under amperometric conditions in a flow system, the sensor achieved a linear range from 1.0 × 10−6 to 6.
The document describes the design and application of powder composite electrodes made of Cu, Co, Ni, Pt and Ir for use in electrosynthesis and electroanalysis in alkaline solutions. The electrodes were prepared by mixing 95% metal powder with 5% polyvinyl chloride binder. Characterization showed the electrodes had a rough, porous surface and good electrochemical stability, with higher current densities than metal sheet electrodes. Cyclic voltammetry testing demonstrated the composite electrodes had good stability over multiple cycles for electrooxidation reactions like ethanol oxidation in KOH solution. The composite electrodes are suitable for electrochemistry research applications requiring stable, conductive electrodes.
Sensor applications of NPs using Cyclic Voltammetry: A ReviewIRJET Journal
This document discusses the use of cyclic voltammetry and nanoparticles for sensor applications. It provides background on cyclic voltammetry, describing how it is used to study redox processes and electron transfer reactions. The document then reviews several studies where nanoparticles were used as sensors in cyclic voltammetry experiments. Specifically, it summarizes research where copper zinc aluminum oxide nanoparticles detected lead and tin at millimolar concentrations within 3 seconds. It also summarizes work where lanthanum silicate nanoparticles doped with rare earth ions sensed paracetamol at the millimolar level within 3 seconds, showing potential for sensitive and rapid detection of medicines.
The document summarizes research on the electrochemical deposition of lead dioxide nanostructured thin films. Key findings include:
- Lead dioxide nanostructures were successfully deposited on gold-coated substrates by anodic electrochemical deposition using nitric acid and lead chloride as reactants. The morphology was influenced by deposition parameters like potential, temperature, and pH.
- Deposition at higher temperatures (60°C vs room temperature) resulted in faster growth rates and denser nanostructures, as seen by SEM images.
- Both anodic and cathodic deposition were studied. Cathodic deposition allowed formation of different lead oxide phases depending on conditions, while anodic deposition selectively formed PbO2.
- The work provides a
Surface Activation of C-sp3 in Boron-Doped Diamond ElectrodeAlejandro Medel
Abstract C-sp2 (graphite) impurities are undesirable in synthetic diamond electrodes (C-sp3), because they can affect the electrochemical response. In this work, we demonstrate that Csp3 surfaces can be activated successfully by applying an anodic current density corresponding to sufficiently high potential where the hydroxyl radicals (●OH) are generated. The
effectiveness of this activation process was verified by Raman spectroscopy, X-ray diffraction, scanning electron microscopy, and cyclic voltammetry.
This document summarizes a study that characterized graphite anodes from lithium-ion battery cells after fast charging. Multi-scale characterization techniques revealed increased disorder near the edges of graphite particles in anodes that experienced lithium plating during fast charging. Specifically, transmission electron microscopy showed wavy graphite fringes and higher d-spacings near particle edges, indicating greater lattice disorder extending 20 nm into the bulk. This disorder hinders lithium ion intercalation and favors lithium plating during repeated fast charging. Scanning electron microscopy also showed fast-charged anodes were thicker due to accumulated electrolyte reduction products in pores.
International Refereed Journal of Engineering and Science (IRJES)irjes
International Refereed Journal of Engineering and Science (IRJES) is a leading international journal for publication of new ideas, the state of the art research results and fundamental advances in all aspects of Engineering and Science. IRJES is a open access, peer reviewed international journal with a primary objective to provide the academic community and industry for the submission of half of original research and applications.
Synthesis, Characterization and Electro analytical Applications of Nitrogen D...IRJET Journal
This document summarizes research on synthesizing and characterizing nitrogen-doped ordered mesoporous carbon (CMK-3) for use as a modified electrode in electrochemical analysis. CMK-3 was synthesized using honey as a natural carbon source and SBA-15 mesoporous silica as a template. Characterization with XRD, BET, SEM and TEM showed the carbon replicated the hexagonal structure of SBA-15 and had a surface area of 587.8 m2/g. Cyclic voltammetry demonstrated the CMK-3 modified electrode could selectively determine dopamine, L-cysteine, ascorbic acid and paracetamol through well-defined oxidative/reductive peaks
Synthesis and optimisation of ir o2 electrocatalysts by adams fusion method f...materials87
The document describes the synthesis and optimization of iridium dioxide (IrO2) electrocatalysts for oxygen evolution reaction (OER) in solid polymer electrolyte electrolyzers. IrO2 was synthesized using an Adams fusion method by varying synthesis duration (0.5-4 hours) and temperature (250-500°C). Characterization showed that increasing synthesis time and temperature improved crystallinity and increased particle size. Electrochemical testing revealed that IrO2 synthesized for 2 hours at 350°C exhibited the best electrocatalytic activity toward OER compared to a commercial IrO2 catalyst. Higher temperatures and longer times favored larger, more crystalline particles but decreased surface area and activity.
Synthesis and optimisation of ir o2 electrocatalysts by adams fusion method f...sudesh789
This document discusses the synthesis and optimization of iridium dioxide (IrO2) electrocatalysts for use in solid polymer electrolyte electrolyzers through an adaptation of the Adams fusion method. The synthesis duration and temperature were varied to determine their effect on the physical and electrochemical properties of the IrO2 catalysts. X-ray diffraction analysis showed that increasing the synthesis duration and temperature increased the crystallinity and particle size of the IrO2. Chronoamperometry testing revealed that a synthesis of 2 hours at 350°C produced an IrO2 catalyst with better electrocatalytic activity for oxygen evolution than a commercial IrO2 catalyst.
Synthesis, characterisation and evaluation of ir o2 based binary metal oxide ...suresh800
This document describes the synthesis, characterization, and evaluation of various binary metal oxide electrocatalysts for the oxygen evolution reaction in solid polymer electrolyte electrolyzers. Specifically, IrO2, IrxRu1-xO2, IrxSnx-1O2 and IrxTax-1O2 (where 1 ≥ x ≥ 0.7) were synthesized using the Adams fusion method, and then characterized using XRD, SEM, TEM, and electrochemical techniques. XRD analysis showed that solid solutions were formed when RuO2, SnO2, or Ta2O5 were added to IrO2. TEM analysis revealed nanosize particles for all synthesized metal oxides. Electrochemical
This document summarizes the electrochemical synthesis and corrosion inhibiting properties of a poly N-methyl aniline coating doped with di-N-propyl malonic acid on stainless steel. Cyclic voltammetry was used to polymerize N-methyl aniline in a solution containing di-N-propyl malonic acid on a stainless steel electrode. An adherent red polymer film was obtained. Electrochemical impedance spectroscopy and potentiodynamic polarization techniques showed that this polymer coating provided excellent corrosion protection of stainless steel in 0.5M sulfuric acid solution, with inhibition efficiencies above 99% as indicated by large increases in charge transfer resistance and decreases in corrosion current density compared to uncoated stainless steel.
This study examined the surface area that contributes to current density in microbial electrochemical systems. Experiments used a graphite plate working electrode and Geobacter subterraneus to form biofilms on both sides. Chronoamperometry showed biofilms formed on both sides. Cyclic voltammetry identified a direct electron transfer mechanism with a defined potential. Confocal laser scanning microscopy and modeling found the biofilms were uniformly thick at ~75 μm and contributed equally to the current density of ~2.5 A/m2, demonstrating both sides of a planar electrode can transfer electrons regardless of orientation.
The document discusses microbial fuel cells (MFCs) as an alternative for producing clean electricity. MFCs take advantage of microbial metabolism to generate electricity directly. They consist of an anode where microorganisms oxidize organic substrates and release electrons, and a cathode where oxygen is reduced. Microbes can transfer electrons to the anode through either direct contact or electron shuttles like cytochromes. While power outputs from MFCs have increased significantly in recent years, further improvements are still needed before they can compete commercially with other energy technologies. Understanding microbial electron transfer mechanisms and ecology is crucial to optimizing MFCs.
A closed loop ammonium salt system for recovery of high-purity lead tetroxide...Ary Assuncao
This document describes a closed-loop hydrometallurgical process for recovering high-purity lead tetroxide from spent lead-acid battery paste. The process involves leaching the paste with a mixed solution of ammonium acetate, acetic acid, and hydrogen peroxide. The leachate is then reacted with ammonium carbonate to precipitate lead carbonate. Impurities are removed during leaching and precipitation. The regenerated leachate is recycled for the next leaching. Lead carbonate is calcined to produce lead tetroxide with low impurity levels meeting industry standards. This process allows for reagent recirculation and production of a high value lead recovery product.
Synthesis of Spinel based Catalysts by Wet chemical methods for Colour Remova...PranavkumarRana
The study aimed at color removal and COD degradation of
synthetic wastewater of methylene blue dye via photocatalysis using various spinel catalysts
prepared by different methods. The methylene blue dye with strong azo bond with structure
made up of autochrome and chromophore. The Azo dyes are widely used in textile, paper and
leather industries. The present study is essentially related to the degradation of selected
methylene blue and dye from synthetic dye wastewater however it has been extended to actual
industrial effluents. In order to control wastewater pollution due to dyes the UV-Photocatalytic
degradation technology has been carried out by some researchers using spinel catalysts. Spinel
catalysts are oxides with general formula AB2O4 where A and B are the rare earth, A has
octahedral site and B has tetrahedral site. alkaline earth, alkali metals and transition metal
cations which are expected to be able to overcome the limitations of semiconductors as
photocatalysts.
This document summarizes research on electrodepositing silver nanoparticles onto carbon sphere surfaces using a pulse current. Key findings include:
1) Silver nanoparticles were successfully electrodeposited with a size of 100-400nm after 2 minutes using a pulse current.
2) Deposition occurred on accessible carbon surface sites, forming a monolayer of scattered nanoparticles. Continued deposition led to larger particles and multilayers.
3) Pulse current helped manage monolayer deposition compared to direct current, controlling particle size and number of layers.
This document summarizes the synthesis, characterization, and evaluation of various IrO2-based binary metal oxide electrocatalysts for the oxygen evolution reaction. IrO2, IrxRu1-xO2, IrxSnx-1O2 and IrxTax-1O2 (where x is between 1 and 0.7) were synthesized via an adapted Adams fusion method. X-ray diffraction and electron microscopy showed the materials formed nanocrystalline solid solutions. Electrochemical testing found that adding RuO2, SnO2, or Ta2O5 to IrO2 improved its catalytic performance for oxygen evolution. Specifically, Ir0.7Ru0.3O2 exhibited the best
A high-capacity lithium-air battery with Pd modified carbon nanotube sponge c...liaoss
1) The document describes a lithium-air battery with a free-standing, highly porous carbon nanotube (CNT) sponge cathode modified with palladium (Pd) nanoparticles.
2) The Pd-CNT sponge cathode provides a continuous pathway for lithium ions, oxygen, and electrons to flow, enabling high capacity discharge reactions in the battery.
3) The battery utilizes an ionic liquid electrolyte and a lithium super ionic conductor (LiSICON) ceramic plate to protect the lithium metal anode. This allows the battery to operate stably in open air conditions with capacities as high as 9092 mAh/g.
PIERRA M., TRABLY E., GODON J.J., BERNET N. Successful enrichment procedure for electroactive biofilm formation from environmental sample. MFC4 / 4th International Microbial Fuel Cell Conference, September 1st - 4th, 2013, Cairns, Queensland, AUSTRALIA
This chapter describes the fabrication of a zirconia nanoparticle-decorated reduced graphene oxide (ZrO2/rGO) nanocomposite for an electrochemical sensor to detect the anticancer drug regorafenib. Characterization using XRD, FT-IR, XPS, TEM and EDX confirmed the successful synthesis of ZrO2 nanoparticles on rGO. Electrochemical tests using cyclic voltammetry and differential pulse voltammetry showed the ZrO2/rGO modified electrode has excellent electrocatalytic activity for regorafenib oxidation, with a wide linear detection range of 11-343 nM and a low detection limit of 3.7 nM. The sensor also demonstrated good
This document presents a study evaluating the use of a gold screen-printed electrode as an electrochemical sensor for the rapid determination of levodopa. Levodopa is the primary drug used to treat Parkinson's disease. The study found that using the electrooxidation of levodopa at a potential of +0.63 V in an acetate buffer at pH 3.0, the sensor provided a linear calibration curve from 9.9 × 10−5 to 1.2 × 10−3 mol L−1 with a detection limit of 6.8 × 10−5 mol L−1. Under amperometric conditions in a flow system, the sensor achieved a linear range from 1.0 × 10−6 to 6.
The document describes the design and application of powder composite electrodes made of Cu, Co, Ni, Pt and Ir for use in electrosynthesis and electroanalysis in alkaline solutions. The electrodes were prepared by mixing 95% metal powder with 5% polyvinyl chloride binder. Characterization showed the electrodes had a rough, porous surface and good electrochemical stability, with higher current densities than metal sheet electrodes. Cyclic voltammetry testing demonstrated the composite electrodes had good stability over multiple cycles for electrooxidation reactions like ethanol oxidation in KOH solution. The composite electrodes are suitable for electrochemistry research applications requiring stable, conductive electrodes.
Sensor applications of NPs using Cyclic Voltammetry: A ReviewIRJET Journal
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Electrochemical Behavior of L-Tyrosine at Poly (Dicyclomine Hydrochloride) Fi...paperpublications3
Abstract: An electrochemical method for the determination of L-Tyrosine (LTY) using a dicyclomine hydrochloride (DICY) polymer film modified carbon paste electrode. The surface morphology of poly (DICY) modified carbon paste electrode was characterized by SEM. The modified electrode showed excellent electro catalytic activity towards the oxidation of LTY in 0.1 M phosphate buffer solution of pH 6.5. The effect of pH, concentration and scan rate were studied at the bare carbon paste electrode and poly (DICY) modified carbon paste electrode were investigated. Increase of LTY concentration shows linear increase in oxidation peak current. The linear relationship was obtained between the anodic peak current (Ipa) and concentration LTY in range 2×10-5 M to 1×10-3 M with correlation coefficient of 0.9984. The low detection limit (LOD) and low quantification limit (LOQ) of LTY were detected. The cyclic voltammetric studies indicated that the oxidation of LTY at the modified electrode surface was irreversible; adsorption controlled and undergoes a one electron transfer process at the poly (DICY) film modified carbon paste electrode. The modified electrode showed high sensitivity, detection limit, high reproducibility, easy preparation and regeneration of the electrode surface.
Maiyalagan,Performance of carbon nanofiber supported pd ni catalysts for elec...kutty79
Carbon nanofibers (CNF) supported Pd–Ni nanoparticles have been prepared by chemical reduction
with NaBH4 as a reducing agent. The Pd–Ni/CNF catalysts were characterized by X-ray diffraction
(XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical
voltammetry analysis. TEM showed that the Pd–Ni particles were quite uniformly distributed on the
surface of the carbon nanofiber with an average particle size of 4.0 nm. The electro-catalytic activity of
the Pd–Ni/CNF for oxidation of ethanol was examined by cyclic voltammetry (CV). The onset potential
was 200mV lower and the peak current density four times higher for ethanol oxidation for Pd–Ni/CNF
compared to that for Pd/C. The effect of an increase in temperature from 20 to 60 ◦C had a great effect on
increasing the ethanol oxidation activity
Performance of carbon nanofiber supported pd–ni catalysts for electro oxidati...suresh899
Carbon nanofibers (CNF) supported Pd–Ni nanoparticles have been prepared by chemical reduction
with NaBH4 as a reducing agent. The Pd–Ni/CNF catalysts were characterized by X-ray diffraction
(XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical
voltammetry analysis. TEM showed that the Pd–Ni particles were quite uniformly distributed on the
surface of the carbon nanofiber with an average particle size of 4.0 nm. The electro-catalytic activity of
the Pd–Ni/CNF for oxidation of ethanol was examined by cyclic voltammetry (CV). The onset potential
was 200mV lower and the peak current density four times higher for ethanol oxidation for Pd–Ni/CNF
compared to that for Pd/C. The effect of an increase in temperature from 20 to 60 ◦C had a great effect on
increasing the ethanol oxidation activity.
Performance of carbon nanofiber supported pd ni catalysts for electro-oxidati...Science Padayatchi
This document summarizes a study on carbon nanofiber (CNF) supported Pd-Ni catalysts for electro-oxidation of ethanol in alkaline medium. Pd-Ni/CNF catalysts were prepared by chemical reduction and characterized using various techniques. Electrochemical analysis showed the Pd-Ni/CNF catalyst had lower onset potential and 4 times higher peak current density for ethanol oxidation compared to Pd/C. Increasing the temperature from 20 to 60°C greatly enhanced the ethanol oxidation activity of Pd-Ni/CNF.
Performance of carbon nanofiber supported pd–ni catalysts for electro oxidati...sunilove
Carbon nanofibers (CNF) supported Pd–Ni nanoparticles have been prepared by chemical reduction
with NaBH4 as a reducing agent. The Pd–Ni/CNF catalysts were characterized by X-ray diffraction
(XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical
voltammetry analysis. TEM showed that the Pd–Ni particles were quite uniformly distributed on the
surface of the carbon nanofiber with an average particle size of 4.0 nm. The electro-catalytic activity of
the Pd–Ni/CNF for oxidation of ethanol was examined by cyclic voltammetry (CV). The onset potential
was 200mV lower and the peak current density four times higher for ethanol oxidation for Pd–Ni/CNF
compared to that for Pd/C. The effect of an increase in temperature from 20 to 60 ◦C had a great effect on
increasing the ethanol oxidation activity.
Electrooxidation of methanol on carbon supported pt ru nanocatalysts prepared...sunidevi
This document summarizes a study that prepared carbon-supported Pt-Ru nanocatalysts for methanol electrooxidation using a simple ethanol reduction method. The catalysts were characterized using various techniques and tested for their electrocatalytic activity and stability via cyclic voltammetry. The catalyst prepared with a 2-hour reduction time showed higher mass activity and good stability over 100 cycles for methanol electrooxidation compared to other reduction times. The results indicate these catalysts prepared via a low-cost ethanol reduction method have potential as anode catalysts for direct methanol fuel cells.
Electrooxidation of methanol on carbon supported pt ru nanocatalysts prepared...sunilove
This document summarizes a study that prepared carbon-supported Pt-Ru nanocatalysts for methanol electrooxidation using a simple ethanol reduction method. The catalysts were characterized using various techniques and tested for their electrocatalytic activity via cyclic voltammetry. The key findings were:
1) Pt-Ru nanoparticles were successfully synthesized on carbon support using ethanol as a reducing agent without any stabilizers or heat treatment.
2) Characterization showed the catalysts had an FCC crystal structure and particle size around 3.7 nm.
3) Electrochemical testing found the catalyst reduced for 2 hours had the highest mass activity and stability for methanol electrooxidation over 100 cycles.
Electrooxidation of methanol on carbon supported pt ru nanocatalysts prepared...suresh899
Carbon Supported PtRu nanocatalysts have been prepared by simple impregnation reduction method in which Pt and Ru precursors are reduced by ethanol under reflux conditions for different reaction times. The prepared nanocatalysts were characterized by means of XRD, EDAX, ICP-AAS, FESEM and TEM. XRD analyses showed that all nanocatalysts exhibited f.c.c crystal structure, the structure characteristic for pure Pt, except for that reduced at prolonged reaction time of 4h which showed the presence of characteristic peak for Ru metal. The lattice constant calculations indicate that all catalysts are present in unalloyed phase and the average particle size as determined by TEM was in the range of 3.7 nm. The electrocatalytic activities and stability for the prepared nanocatalysts methanol electro-oxidation reaction (MOR) were studied by cyclic voltammetry. The catalysts prepared at 2h reduction time showed higher electrocatalytic activity in terms of mass specific activity and good stability over potential sweep for 100 cycles for methanol electro-oxidation. The results showed that the prepared nanocatalysts are considered as promising electrode catalyst (anode catalyst) for electro-oxidation of methanol in direct methanol fuel cells.
Electrooxidation of methanol on carbon supported pt ru nanocatalysts prepared...Science Padayatchi
This document summarizes a study that prepared carbon-supported Pt-Ru nanocatalysts for methanol electrooxidation using a simple ethanol reduction method. The catalysts were characterized using various techniques and tested for their electrocatalytic activity and stability via cyclic voltammetry. The catalyst prepared with a 2-hour reduction time showed higher mass activity and good stability over 100 cycles for methanol electrooxidation compared to other reduction times. The results indicate these catalysts prepared via a low-cost ethanol reduction method have potential as anode catalysts for direct methanol fuel cells.
This document discusses electrode material migration during pulsed electric field (PEF) treatment of foods. It provides background on how PEF treatment works to inactivate microbes while retaining food quality, but can also lead to undesirable electrochemical reactions and migration of metals from electrodes into the food. The document describes previous research that has studied this problem and suggested ways to control it, such as through pulse parameters and electrode material selection. It then outlines an experimental setup and samples that will be used to further investigate the effect of pulse characteristics and solution pH on electrode material migration in aqueous solutions.
Electrochemical Degradation of Methylen Blue Using Carbon Composite Electrode...iosrjce
Electrochemical oxidation of methylene blue using carbon composite electrode in sodium chloride
solution have been done. The aim of this work was to degradation of methylen blue using the direct oxidation in
undivided electrolysis cell. Carbon composite electrode was prepare by C powder and PVC in 4 mL
tetrahydrofuran (THF) solvent and swirled flatly to homogeneous followed by drying in an oven at 100 °C for 3
h. The mixture was placed in stainless steel mould and pressed at 10 ton/cm2
. Sodium chloride was used
electrolyte solution. The effects of the current and electrolysis time were investigated using cyclic voltammetry,
spectrophotometer UV-Visible and gas chromatography mass spectrometry (GC-MS). The experimental results
showed that the carbon composite electrode have higher effect in the electrochemical degradation of methylene
blue. Based on UV-visible spectra and GC-MS analysis also shows current and electrolysis time for
degradation of methylene blue optimum at 1,5 A and 60 minute, respectively. As a conclusions is this method its
simple equipment, easy operation and friendly for environmental.
Kinetic modelling of nitrate removal from aqueous solution during electrocoag...Alexander Decker
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Electrodeposited Ru Nanoparticles for Electrochemical Reduction of NAD+ to NADHNorth Breeze
This document summarizes research on the electrodeposition of ruthenium nanoparticles on glassy carbon substrates for electrocatalytic reduction of NAD+. Scanning electron microscopy showed that deposition potential influences nanoparticle size and density, with more negative potentials producing smaller, more densely packed nanoparticles. Electrodes with higher nanoparticle density showed lower overpotentials for hydrogen evolution and catalytic activity for NAD+ reduction. The most negative deposition potential produced a ruthenium film with distinct electrochemical behavior, showing high activity for hydrogen evolution. Overall, controlling deposition potential allows tuning of ruthenium nanoparticle morphology for electrocatalytic applications.
IRJET- Electrocoagulation Treatment of Electroplating Industrial EffluentIRJET Journal
The document discusses electrocoagulation treatment of electroplating industrial effluent. Electrocoagulation uses aluminum electrodes connected to a power source, generating aluminum ions and hydroxide ions that remove pollutants from the effluent. The study treated electroplating effluent with high levels of zinc and nickel. Treatment at 4A/m2 current density for 120 minutes reduced zinc levels by 78.9%, but did not significantly reduce nickel levels due to the effluent's low initial pH of 1.7. Increasing pH improved removal of both metals during electrocoagulation treatment.
Experiment 4: Electropolymerized Conducting Polymers.
Introduction:
Conductive polymers (CP) exhibit very useful properties such as flexibility, solubility [1], electrical conductivity, low energy optical transitions, low ionization potential, and high electron affinity.[2] These characterizations make them such effective candidates for many applications such as antistatic and antimagnetic shielding devices[3], microwave attenuation[4], light emitting devices, optical sensors, enzymatic biosensors[5], electronic circuits, and detectors of odors and flavors. The most widely known conducting polymers are polypyrole, polyanaline, and polythiophene. By applying an electrical potential (reversible reaction), these polymers can be reduced. The role of these polymers when they are used as active templates in biosensor applications is the immobilization of dynamic species on the electrode. This will contribute to enhancing the sensitivity and the accuracy of analyte detection. CPs have been used for stabilizing numerous biological species such as enzymes, antibodies, haptens, DNA, and more interestingly the whole cells. [1]
Aim:
The aim of performing this experiment is to create a conducting polypyrrole film which consists of a stabilized enzyme, identify the film and its characteristics, and utilize it as glucose biosensor.
Procedure:
“Refer to Manual for NANO 3101/8302, Electropolymerized Conducting Polymers, Flinders University, p.24-29.”
Results and Discussion:
In the biosensor uses, the deposition of the polymers on the electrode surface can be done by applying an oxidative potential. During this action, the enzymes can be stabilized, and by modifying the deposition time, the amounts of the deposited layer can be recreated. The sensitivity, selectivity, and the accuracy of detection of the biosensors are reliant on the architecture of the polymer, the biological activity of the enzymatic immobilization, and the electropolymerisation circumstances.
In this experiment, the glucose oxidase (enzyme) was immobilized in a conducting polypyrole film on an electrode to find out their appropriateness as a functioning electrode. The performance of the electrode was measured through a Cyclic Voltammogram (CV) of ferricyanide
The geometric area of the electrode was measured by a ruler, and it was found to be 3.14 mm ²which is identical to 0.00314 cm².
The Randles-Sevcik equation is used in the redox reactions
at 25 C °
Where is the peak current, A is the electrode area (cm²), n is the number of electrons involved, C is the concentration of the bulk (mol/ml) for active species, v is the scan rate (V/s), and D is the diffusion coefficient.
n = 1, therefore
, therefore = 0.002756809.
V = 20mV/s = 0.02 V/s, therefore
C = 10 mM = 0.01 mol/L = 0.00001 mol/mL.
can be determined from figure.1
Figure 1: Cyclic Voltammograms (CV) as a function of escalating the scan rate for Platinum Electrode in ferrricyanide solution.
This c ...
Electrochemical sensor 01 mm 717 iit b 2016Muzzamil Eatoo
Electro-chemical sensors principle, working, problems, sensing properties, selection of electrode for these sensors, electrode synthesis and properties, and best electrodes.
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This document discusses suffixes and terminology used in medicine. It begins by listing common combining forms used to build medical terms and their meanings. It then defines several noun, adjective, and shorter suffixes and provides their meanings. Examples are given of medical terms built using combining forms and suffixes. The document also examines specific medical concepts in more depth, such as hernias, blood cells, acromegaly, splenomegaly, and laparoscopy.
The document is a chapter from a medical textbook that discusses anatomical terminology pertaining to the body as a whole. It defines the structural organization of the body from cells to tissues to organs to systems. It also describes the body cavities and identifies the major organs contained within each cavity, as well as anatomical divisions of the abdomen and back.
This document is from a textbook on medical terminology. It discusses the basic structure of medical words and how they are built from prefixes, suffixes, and combining forms. Some key points:
- Medical terms are made up of elements including roots, suffixes, prefixes, and combining vowels. Understanding these elements is important for analyzing terms.
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This document is the copyright information for Chapter 25 on Cancer from the 6th edition of the textbook Molecular Cell Biology published in 2008 by W. H. Freeman and Company. The chapter was authored by a team that includes Lodish, Berk, Kaiser, Krieger, Scott, Bretscher, Ploegh, and Matsudaira.
This document is the copyright information for Chapter 24 on Immunology from the 6th edition of the textbook Molecular Cell Biology published in 2008 by W. H. Freeman and Company. The chapter was authored by Lodish, Berk, Kaiser, Krieger, Scott, Bretscher, Ploegh, and Matsudaira.
Nerve cells, also known as neurons, are highly specialized cells that process and transmit information through electrical and chemical signals. This chapter discusses the structure and function of neurons, how they communicate with each other via synapses, and how signals are propagated along neurons through changes in their membrane potentials. Neurons play a vital role in the nervous system by allowing organisms to process information and coordinate their responses.
This document is the copyright information for Chapter 22 from the 6th edition of the textbook "Molecular Cell Biology" published in 2008 by W. H. Freeman and Company. The chapter is titled "The Molecular Cell Biology of Development" and is authored by Lodish, Berk, Kaiser, Krieger, Scott, Bretscher, Ploegh, and Matsudaira.
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A proprietary approach developed by bringing together the best of learning theories from Psychology, design principles from the world of visualization, and pedagogical methods from over a decade of training experience, that enables you to: Learn better, faster!
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The recent surge in pro-Palestine student activism has prompted significant responses from universities, ranging from negotiations and divestment commitments to increased transparency about investments in companies supporting the war on Gaza. This activism has led to the cessation of student encampments but also highlighted the substantial sacrifices made by students, including academic disruptions and personal risks. The primary drivers of these protests are poor university administration, lack of transparency, and inadequate communication between officials and students. This study examines the profound emotional, psychological, and professional impacts on students engaged in pro-Palestine protests, focusing on Generation Z's (Gen-Z) activism dynamics. This paper explores the significant sacrifices made by these students and even the professors supporting the pro-Palestine movement, with a focus on recent global movements. Through an in-depth analysis of printed and electronic media, the study examines the impacts of these sacrifices on the academic and personal lives of those involved. The paper highlights examples from various universities, demonstrating student activism's long-term and short-term effects, including disciplinary actions, social backlash, and career implications. The researchers also explore the broader implications of student sacrifices. The findings reveal that these sacrifices are driven by a profound commitment to justice and human rights, and are influenced by the increasing availability of information, peer interactions, and personal convictions. The study also discusses the broader implications of this activism, comparing it to historical precedents and assessing its potential to influence policy and public opinion. The emotional and psychological toll on student activists is significant, but their sense of purpose and community support mitigates some of these challenges. However, the researchers call for acknowledging the broader Impact of these sacrifices on the future global movement of FreePalestine.
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Electrochemical sensor for voltammetric determination of
1. Int. J. Electrochem. Sci., 4 (2009) 1167 - 1177
International Journal of
ELECTROCHEMICAL
SCIENCE
www.electrochemsci.org
Electrochemical Sensor for Voltammetric Determination of
Catechol Based on Screen Printed Graphite Electrode
Gaber A. M. Mersal*
Chemistry Department, Faculty of Science, South Valley University, Qena, Egypt
*
E-mail: gamersal@yahoo.com
Received: 17 July 2009 / Accepted: 12 August 2009 / Published: 25 August 2009
A simple, rapid and a highly selective method for the direct electrochemical determination of catechol
based on the electrochemical oxidation at the screen printed graphite electrode was discussed. The
electrochemical behavior of catechol was studied by cyclic voltammetric techniques at the screen
printed graphite electrode. Catechol showed one anodic peak (Epa) and one cathodic peak (Epc) at 204
and 145 mV (vs. SCE), respectively, in phosphate buffer (pH 6). Square wave voltammetry was used
for the direct electrochemical determination of catechol. The effect of different experimental and
instrumental parameters such as; type of supporting electrolytes, solution pH, applied potential, and
scan rate were examined. The oxidation peak currents showed a linear range from 1x10-6
to 1x10-4
M
with a 0.999 correlation coefficient. A 2.9x10-7
M lower detection limit was obtained. The effect of
ascorbic acid as the most interfering substances on the peak height of catechol was examined. Using
square wave voltammetry, catechol and ascorbic acid showed a well defined two separated oxidation
peaks. The proposed method has been applied for the determination of catechol in the absence and
presence of ascorbic acid in a water sample.
Keywords: Screen printed graphite electrode, Catechol, Cyclic voltammetry, Square wave
voltammetry
1. INTRODUCTION
Beginning of the last decade, screen-printing technology was widely used for the production of
microelectronics [1]. This technology offered the chance for the production of simple, sensitive, rapid,
cheap and reproducible electrochemical sensors [2-4]. Several materials were used for the production
of screen printed electrochemical electrodes such as gold, platinum, graphite, copper and silver. These
types of materials used for the production of the working electrode influences the electrochemical
behavior of the produced sensor.
2. Int. J. Electrochem. Sci., Vol. 4, 2009 1168
The electrochemistry of several organic and inorganic compounds has been investigated [1, 5-
10] at the surface of screen printed electrodes. Due to the importance and involvement of phenolic
compounds in different fields- such as environmental, medical, food industry, their electrochemical
behavior were examined using different types of sensors and biosensors [11-13].
Catechol (1,2- dihydroxybenzene) is one of the most important phenolic compounds which
occurs naturally in fruits and vegetables and can be released to the environment during its manufacture
and use. It is also detected at low levels in, groundwater, drinking-water, soil samples and in
wastewaters from coal conversion. Catechol has a great importance in both biological and
environmental analysis fields and this due to its excellent electrochemical activity and can be used for
the characterization of different analytical methods. Different analytical methods were used for the
determination of catechol such as spectrophotometry [14, 15] and high-performance liquid
chromatography [16]. The electrochemical determination of catechol was also studied using enzymatic
[17-23] or non enzymatic electrodes [24-32]. The enzymatic method for the determination of catechol
suffers from some disadvantages such as high cost due to the enzyme used, low stability and limited
binding of the enzyme to solid surfaces [24]. The non enzymatic electrodes used for studying the direct
electrochemistry of catechol was also examined using different types of electrodes such as mesoporous
platinum [25-26] and gold electrode [27]. The direct electrochemical determination of catechol based
on the oxidation of catechol at the electrode surface to o-quinone. Different kinds of electrodes were
used for the electrochemical determination of catechol such as Born-Doped Diamond electrode [28],
chemically modified electrodes such as carbon nanotube (CNT) [29], multiwall carbon nanotubes
(MWNT) [28,30-31], modified glassy carbon electrodes (GCE) [32].
Modification of the electrodes increased the selectivity of detection but have a high cost due to
the modifiers used. Using carbon nanotubes increased also the cost of the used electrodes. From the
literature survey no screen printed electrodes were used for the electrochemical determination of
catechol. The aim of this work is to study the electrochemical behavior and the direct electrochemical
determination of catechol by incorporating both the advantages of graphite screen printed electrodes
and the advantages of electrochemical techniques which lead to a low cost, more simplicity and
increasing the sensitivity, selectivity and reproducibility of the method.
2. EXPERIMENTAL PART
2.1. Electrode and electrochemical instruments
Cyclic voltammetry (CV) and square wave voltammetry were preformed using an Autolab
potentiostat PGSTAT 302 (Eco Chemie, Utrecht, The Netherlands) driven by the General purpose
Electrochemical Systems data processing software (GPES, software version 4.9, Eco Chemie).
Electrochemical cell with three electrodes was used; a screen printed graphite electrode was used as
working electrode, these sensors were fabricated at the Gesellschaft für Biotechnologische Forschung
mbH (GBF) Braunschweig, Germany, using screen-printing technology. They have graphite working
electrodes with an area of about ~ 6.3 mm2
. The graphite layer screen-printed onto a gold layer. The
gold layer was included to avoid a potential drop over the surface caused by the relatively low
3. Int. J. Electrochem. Sci., Vol. 4, 2009 1169
conductivity of the graphite. The graphite paste was Electrodag 421SS (Acheson Colloids, Plymouth,
UK) and the gold paste was No. 5715, and the AgPd-paste used for connecting lines was No. 7474
(DuPont, Bad Homburg, Germany). The isolation of connecting lines was achieved by printing
isolating pastes, which were insulation 240-SB (ESL Europe, Munich, Germany). The ceramic
substrates were obtained from LaserTec Services (Nürnberg, Germany). Printing was carried out using
the half-automatic printing machine Microtronic II (EKRA, Kirchheim, Germany). All metal-based
pastes and the glass passivation were fired for 60 min with a peak temperature of 850˚C (10 min) in a
Firing oven BTU 7354-M (BTU, Farnborough, UK) according to the paste manufacturers
recommendations. SCE was used as a reference electrode and platinum wire was used as a counter
electrode. The supporting electrolyte was filled in the electrochemical cell (10 mL) and catechol added
to the cell to get the desired concentration. The pH values were measured using a Metrohom pH-meter
with a combined glass electrode
2.2. Reagents
All chemicals used were of analytical grade and used without any further purification. Catechol
and ascorbic acid were obtained from Sigma-Aldrich. Phosphate buffer solution was prepared by
mixing suitable amounts of 0.1 M Na2HPO4 and NaH2PO4. H3BO3, NaOH, KCl, H3PO4, CH3COOH
were of obtained from Merck. Stock solutions of catechol were freshly prepared daily. Double distilled
water was used for the preparation of solutions.
3. RESULTS AND DISCUSSION
3.1. Electrochemical behavior of catechol
The electrochemical behavior of catechol was examined using cyclic voltammetry at a graphite
screen printed electrode. Catechol gave two redox peak potentials, one anodic peak potential (Epa) and
one cathodic peak potential (Epc) at 204 and 145 mV, respectively. The difference between the
oxidation and reduction peaks (∆Ep) for catechol at screen printed graphite electrode was 58 mV. This
indicates that the oxidation of catechol is a reversible behavior and 1-electron transfer step. The
general scheme for the electrochemical oxidation of catechol indicated by 2-electron transfer step. For
screen printed graphite electrode 2- electron transfer step was indicated. This can be expressed by the
lack of stability due to the polymerization of the products, which may result from 1-electron transfer
reactions coupled to the formation of radicals which then polymerize. The effect of number of cycles
was examined from 1 to 10, and no remarkable effect was obtained in the number of cycles examined.
3.2. Effect of supporting electrolyte and pH
The effect of different types of supporting electrolytes was examined on the peak current
response of 1.0 mM catechol. The supporting electrolytes examined include 0.1 M from: Britton-
Robinson (BR) buffer, acetate, sodium sulphate, borate and phosphate buffer. It was found that
4. Int. J. Electrochem. Sci., Vol. 4, 2009 1170
catechol gave the highest oxidation peak current in 0.1 M phosphate buffer, therefore phosphate buffer
was selected for further studies.
The effect of pH on the peak current and peak potential of the anodic and cathodic peaks of
catechol were examined in the range from 5 to 10 using 0.1 M phosphate buffer. Figure 1a showed the
obtained results for 1.0 mM catechol.
Figure 1a. The effect of pH on (a) the peak current response (b) peak potential of 1mM
Catechol 0.1 M phosphate buffer pH 6, using screen printed graphite Electrode. Scan rate 10 mVs-1
.
Figure 1b. The effect of pH on (a) the peak current response (b) peak potential of 1mM
catechol. Other conditions are the same as Fig. 1a
This Fig. showed the dependence of the oxidation and reduction peaks on the pH of the supporting
electrolyte. The oxidation peak for catechol increased up to pH 6 and still stable from pH 6 to pH 8 and
at higher pH values the oxidation peak decreased. Also the reduction peak current of catechol
increased from pH 5 to pH 7 and at higher pH values the peak current response deceased. From Figure
5 6 7 8 9 10
5.0x10
-6
1.0x10
-5
1.5x10
-5
2.0x10
-5
2.5x10
-5
Current/A
pH
Ip anodic
Ip cathodic
5 6 7 8 9 10
-0.05
0.00
0.05
0.10
0.15
0.20
0.25
0.30
E(V)
pH
Ep anodic
Ep cathodic
5. Int. J. Electrochem. Sci., Vol. 4, 2009 1171
1a it was clearly that the oxidation peak response is higher than the reduction peak current response, so
the oxidation peak was selected for the analytical determination of catechol for further investigations at
pH 6.
The effect of pH on the peak potentials of catechol was examined from pH 5 to pH 10, by
increasing the pH of supporting electrolyte the peak potential for anodic and cathodic peaks shifted to
more negative values (Figure 1b).
The effect of ionic strength for the phosphate buffer on the anodic peak current of 1.0 mM
catechol was studied using 0.05, 0.1, 0.15, 0.2 M phosphate buffer at pH = 6. By increasing the ionic
strength of the supporting electrolyte, the peak current increased, so 0.2 mM phosphate buffer pH = 6
was chosen for further studies.
3.3. Effect of the applied potential
The effect of applied potential on the anodic and cathodic peak currents was investigated using
a wide range from -1.6 V to 0.0 V. For anodic and cathodic peak currents, by shifting the applied
potential to more positive values the peak currents decreased (Figure 2). The effect of applied potential
on the anodic and cathodic peak position was also examined. By shifting the potential to more positive
value, no remarkable effect on the cathodic peak potential was observed, but for anodic peak, a little
shift towards more positive values was observed (Figure 2).
Figure 2. The effect of applied potential on the anodic peak current and anodic peak potential for 0.1
mM catechol in 0.1 M phosphate buffer pH 6, using screen printed graphite Electrode. Scan rate 10
mVs-1
-2.0 -1.6 -1.2 -0.8 -0.4 0.0 0.4 0.8
1.9x10
-5
2.0x10
-5
2.1x10
-5
2.2x10
-5
2.3x10
-5
Peak Hieght
Peak position
Applied potential (V)
Currentheight(A)
0.210
0.212
0.214
0.216
0.218
0.220
0.222
0.224
0.226
0.228
Peakposition(V)
6. Int. J. Electrochem. Sci., Vol. 4, 2009 1172
3.4. Effect of scan rate
The effect of scan rate (ν) on the cyclic voltammetric response was investigated, results
obtained are depicted in Figure 3a. It can be seen that by increasing the scan rate, the anodic and
cathodic peak currents increased, and both anodic and cathodic peak potentials moved. The anodic
peak potential shifted to more positive potential values, while that of cathodic peaks shifted to more
negative values. From the plotting the relation between the square root of scan rate (ν1/2
) versus the
peak current, it was found that the peak current proportional to the square root of scan rate in the range
from 10 to 300 mVs-1
for anodic and cathodic peaks (Figure 3b).
Figure 3 (a) Cyclic voltammograms for 1 mM catechol at different scan rates: a) 10, b) 25, c) 50, d)
100, e) 150, f) 200 and g) 250 mV/s.
Figure 3 (b) Effect of scan rate on the peak current response of 1.0 mM catechol in 0.2 M phosphate
buffer pH 6, scan rate 50 mV s-1
.
2 4 6 8 10 12 14 16 18
-8.0x10
-5
-6.0x10
-5
-4.0x10
-5
-2.0x10
-5
0.0
2.0x10
-5
4.0x10
-5
6.0x10
-5
8.0x10
-5
Y = 0.15 -1.3x10
-4
X
R
2
= 0.996
Y = -7.2x10
-6
+ 5.2x10
-6
X
R
2
= 0.999
PeakHeight(A)
v
1/2
/ (mV/s)
1/2
anodic peak
cathodic peak
7. Int. J. Electrochem. Sci., Vol. 4, 2009 1173
3.5. Calibration curve and Detection limit
Square wave voltammetry was used for the direct determination of catechol. Catechol showed a
well defined anodic peak using the following optimum conditions: screen printed graphite electrode as
a working electrode, square wave voltammetry with 0.05 V step time, 0.02 V amplitude in 0.2 M
phosphate buffer (pH = 6). Catechol showed a linear range from 1x10-6
to 1x10-4
M (Figure 4) with a
correlation coefficient of 0.9997 and a standard deviation of 7.677 x10-7
. The detection limit for
catechol was calculated based on a three signal to noise ration and it was found of 2.9x10-7
M
Figure 4. Relationship between the response current and catechol concentration using square wave
voltammetry. Parameters are reported in the text.
3. 6. Reproducibility
The reproducibility of the results was examined by successive ten measurements of 1x10-4 M
catechol using the optimum conditions mentioned above. The relative standard deviation (RSD) was
calculated and it was found to be 3.9%. Also the reproducibility of the screen printed graphite
electrode response was examined by the determination of 1X10-4
M Catechol using ten screen printed
electrodes and the RSD was found with 2.4% which indicated that this method give a good
reproducibility for the obtained results.
3.7. Effect of Interferences
The effect of ascorbic acid, as a one of the most interfering substances in the
electrochemical determination of some organic compounds was examined on the response of catechol.
Figure (5a) showed the effect of different concentrations of ascorbic acid on the peak height of 0.5 mM
0.0 2.0x10
-4
4.0x10
-4
6.0x10
-4
8.0x10
-4
1.0x10
-3
0.0
1.0x10
-5
2.0x10
-5
3.0x10
-5
4.0x10
-5
5.0x10
-5
6.0x10
-5
Y = 9.31x10
-6
+ 0.054X
R
2
= 0.999
Current(A)
Catechol concetration (M)
8. Int. J. Electrochem. Sci., Vol. 4, 2009 1174
catechol and Table 1. summarizes the collected data. From Table 1, the addition of ascorbic acid has a
little effect on the peak height of catechol, but by increasing the ascorbic acid concentrations the
percentage of error increased to 8%. Also the effect of different concentrations of catechol on the peak
height of 1.0 mM ascorbic acid was also examined (Figure 5b). No marked effect was observed for the
ascorbic acid response. So catechol can be detected in the presence of ascorbic acid and it is also
possible to detect ascorbic acid under the same conditions for the determination of catechol without
any interferences.
Figure 5. (a) Effect of ascorbic acid addition on the peak height of 5x10-4
M catechol.
Figure 5. (b) Effect of catechol acid addition on the peak height of 5x10-4
M ascorbic acid.
-1.0 -0.5 0.0 0.5 1.0 1.5
2.0x10
-5
3.0x10
-5
4.0x10
-5
5.0x10
-5
6.0x10
-5
7.0x10
-5
8.0x10
-5
Current(A)
E (V)
a) 0.0 mM ascorbic acid
b) 0.5 mMascorbic acid
c) 0.5 mM ascorbic acid + 0.1 mM Catechol
d) 0.5 mM ascorbic acid + 0.3 mM Catechol
f) 0.5 mM ascorbic acid + 0.5 mM Catechol
g) 0.5 mM ascorbic acid + 0.7 mM Catechol
h) 0.5 mM ascorbic acid + 0.9 mM Catechol
i) 0.5 mM ascorbic acid + 1.0 mM Catechol
a
b
c
d
e
f
g
i
-0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2
1.5x10
-5
2.0x10
-5
2.5x10
-5
3.0x10
-5
3.5x10
-5
4.0x10
-5
4.5x10
-5
5.0x10
-5
5.5x10
-5
6.0x10
-5
6.5x10
-5
Current(A)
E (V)
a) Buffer only
b) 0.5 mM Catechol
c) 0.5 mM Catechol + 0.1 mM ascorbic acid
d) 0.5 mM Catechol + 0.3 mM ascorbic acid
e) 0.5 mM Catechol + 0.5 mM ascorbic acid
f) 0.5 mM Catechol + 0.7 mM ascorbic acid
g) 0.5 mM Catechol + 1 mM ascorbic acid
a
b
d
e f
c
g
9. Int. J. Electrochem. Sci., Vol. 4, 2009 1175
Table 1. The percentage of errors obtained by the addition of different ascorbic acid concentrations on
1mM catechol using square wave voltammetry. Other parameters as mentioned in the text.
3.8- Analytical Applications:
This method was applied for the determination of catechol in synthetic samples containing
catechol in tap water in the absence and presence of ascorbic acid. The obtained results are listed in
Table 2. In the absence of ascorbic acid a known amount of catechol was added to the water sample,
the quantitative recoveries of 98.6% - 100.3% were obtained (Table 2), while in the presence of
different ascorbic acid concentrations, quantitative recoveries of 97.13% – 102.43% were obtained
(Table 3). So the determination of catechol using screen printed electrodes is reliable and effective
method for the determination catechol.
Table 2. Determination of catechol in tap water in the absence of ascorbic acid
Sample No. Catechol added (uM) Catechol Found
(uM)
Recovery (%)
1
2
3
4
5
10
20
30
40
50
9.86
19.78
29.77
40.12
49.88
98.6
98.9
99.23
100.3
99.76
Table 3. Simultaneous determination of catechol in tap water in the presence of ascorbic acid
Sample No. Ascorbic acid
added to tap
water (mM)
Catechol added
(uM)
Catechol
Found (uM)
Recovery
(%)
1
2
3
4
5
0.1
0.2
0.3
0.4
0.5
30
30
30
30
30
30.25
30.73
29.78
29.14
29.89
100.83
102.43
99.27
97.13
99.63
Ascorbic acid concentration
(mM)
Percentage of error (%)
0.1 1.88
0.3 1.42
0.5 0.94
0.7 2.82
1.0 8.96
10. Int. J. Electrochem. Sci., Vol. 4, 2009 1176
4. CONCLUSIONS
The electrochemical behavior of catechol was examined at the screen printed graphite electrode. The
result showed that catechol gave one anodic oxidation peak in the forward scan and another cathodic
reduction peak in the reverse scan at the surface of screen printed graphite electrode. The main task for
this work was to find a rapid and more sensitive method for the direct electrochemical determination of
catechol by the oxidation at the surface of screen printed graphite electrode. The respective electrode
showed a good sensitivity and selectivity for the electrochemical determination of catechol in the
presence of ascorbic acid
ACKNOWLEDGEMENTS
I would like to thank Prof. U. Bilitewski for supporting the screen printed graphite electrode used in
this work.
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