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- Researchers discovered a new phase of carbon called linear carbon through an explosion at a laboratory, but it caused injuries and was initially unsuccessful. - Later, scientists were able to make progress on synthesizing linear carbon using polyacetylene and its conductive properties. - Polydiacetylenes were also studied as an alternative to polyacetylene due to its stability, with potential applications in sensors, optical limiters and waveguides. Precise synthesis remains a challenge due to instability and potential for explosion.
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Water-splitting photoelectrodes consisting of heterojunctions of carbon nitri...
Quinary and senary non-stoichiometric double perovskites such as Ba2Ca0.66Nb1.34-xFexO6-δ (BCNF) have been utilized for gas sensing, solid oxide fuel cells and thermochemical CO2 reduction. Herein, we examined their potential as narrow bandgap semiconductors for use in solar energy harvesting. A cobalt co-doped BCNF, Ba2Ca0.66Nb0.68Fe0.33Co0.33O6-δ (BCNFCo), exhibited an optical absorption edge at ~ 800 nm, p-type conduction and a distinct photoresponse upto 640 nm while demonstrating high thermochemical stability. A nanocomposite of BCNFCo and g-C3N4 (CN) was prepared via a facile solvent assisted exfoliation/blending approach using dichlorobenzene and glycerol at a moderate temperature. The exfoliation of g-C3N4 followed by wrapping on perovskite established an effective heterojunction between the materials for charge separation. The conjugated 2D sheets of CN enabled better charge migration resulting in increased photoelectrochemical performance. A blend composed of 40 wt% perovskite and CN performed optimally, whilst achieving a photocurrent density as high as 1.5 mA cm-2 for sunlight-driven water-splitting with a Faradaic efficiency as high as ~ 88%.
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sunlight by using photocatalysts to split water into hydrogen and oxygen is an expedient approach to fulfill
the energy demand in a sustainable way along with reducing the emission of greenhouse gases. Even though
the past few decades have witnessed intensive research into inorganic semiconductor photocatalysts, their
quantum efficiencies for hydrogen production from visible photons remain too low for the large scale
deployment of this technology. Visible light absorption and efficient charge separation are two key necessary
conditions for achieving the scalable production of hydrogen from water. Two-dimensional carbon based
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The document summarizes research into preparing mesoporous titania photocatalysts for water treatment applications. Key points include:
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into alternative clean sources of energy. To achieve the goal of a carbon neutral economy, the harvesting of
sunlight by using photocatalysts to split water into hydrogen and oxygen is an expedient approach to fulfill
the energy demand in a sustainable way along with reducing the emission of greenhouse gases. Even though
the past few decades have witnessed intensive research into inorganic semiconductor photocatalysts, their
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deployment of this technology. Visible light absorption and efficient charge separation are two key necessary
conditions for achieving the scalable production of hydrogen from water. Two-dimensional carbon based
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properties such as superior charge transport, tunable energy levels and bandgaps, visible light absorption,
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The document summarizes research into preparing mesoporous titania photocatalysts for water treatment applications. Key points include:
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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,
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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
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In a first line of research, we have described and patented the incorporation of tetrazole groups as carboxylic acid replacements for the sensitization of lanthanide emission. We were able to show how the variation of ligand substituents influences the photophysical properties, allowing us to draw predictions and to adapt the structures for improving the emission efficiency. Some of the compounds have been successfully tested in OLED devices.
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2016.08.15-EG_Poster_SCESv2
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Photocatalytic degradation of some organic dyes under solar light irradiation...
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Electrochemical Degradation of Methylen Blue Using Carbon Composite Electrode...
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.
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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.
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This document discusses solar photocatalysis and solar photocatalytic reactors. It introduces photocatalysis as accelerating photoreactions using a catalyst and light. Titanium dioxide is commonly used as the photocatalyst due to its efficiency, stability, low cost and non-toxic properties. Solar photocatalytic reactors bring photons, photocatalyst and reactants into contact to produce reactions. The two main types are slurry reactors, which provide high surface area but require catalyst separation, and immobilized reactors, which don't require separation but have lower surface area. Applications include water treatment, sterilization and oil decomposition.
Applications of metal nanoparticles in photocatalysis
The document discusses applications of metal nanoparticles in photocatalysis. It provides examples of how metal nanoparticles like gold and palladium can be used as photocatalysts for various reactions like selective oxidation, reduction, and cross-coupling reactions. The nanoparticles enhance reaction rates and selectivity by acting as light absorbers and reaction sites. This allows reactions to occur at milder conditions like lower temperatures and pressures. The use of metal nanoparticles in photocatalysis provides opportunities for more sustainable chemical synthesis.
Roll of nanomaterials in water treatment as photocatalysts copy
This document summarizes research on using nanomaterials as photocatalysts for water treatment. It discusses how nanoparticles have unique properties that make them effective photocatalysts. Several studies are highlighted that synthesized different nanocomposites for degrading organic dyes and pollutants in water under visible light, including ZnCdS nanoparticles on reduced graphene oxide, graphene-gold nanocomposites, and graphene composites with SnO2 and TiO2. These nanocomposites showed enhanced photocatalytic activity compared to their individual components for degrading dyes like Rhodamine B under visible light irradiation.
TiO2
1. TiO2 is an effective photocatalyst for water splitting under UV light through generating electron-hole pairs, but has a large bandgap only absorbing UV light.
2. Nitrogen doping of TiO2 has been explored as a way to narrow the bandgap and enable absorption of visible light, but the exact chemical nature of incorporated nitrogen is unclear from characterization techniques.
3. Preparation methods can result in substitutional or interstitial nitrogen in the TiO2 lattice, but there is no clear correlation between method used and nitrogen state incorporated.
Mechanistic aspects of C-C cross coupling reaction
The document discusses palladium-catalyzed cross-coupling reactions, which were awarded the 2010 Nobel Prize in Chemistry. It summarizes the key reactions including Suzuki, Negishi, Stille, Sonogashira, and Heck reactions. These reactions involve the coupling of organic electrophiles and nucleophiles through oxidative addition, transmetallation, migratory insertion, and reductive elimination steps using a palladium catalyst. The document also discusses the mechanisms and factors influencing these important C-C bond forming reactions.
final accept-Optical and structural properties of TiO2 nanopowders with Co-Ce...
final accept-Optical and structural properties of TiO2 nanopowders with Co-Ce...nasrollah najibi ilkhchy
This document discusses a study on the optical and structural properties of TiO2 nanopowders doped with 2 mol% cerium and 4 mol% cobalt. X-ray diffraction analysis showed that cerium doping inhibited the formation of the rutile phase of titanium dioxide and promoted retention of the anatase phase at higher calcination temperatures. Optical absorption spectroscopy indicated that doping reduced the band gap of titanium dioxide from 3.21 eV to 3.14-3.20 eV. The crystallite size decreased with doping while the surface area increased compared to undoped titanium dioxide.Andreiadis PhD Presentation
The main objective of my PhD research at CEA Grenoble (M. Mazzanti, R. Demadrille) was related to a better understanding of the structure-property relationship in emissive lanthanide complexes with potential applications in opto-electronic devices. This was achieved by a careful design of lanthanide antennas based on either organic chromophores or transition metals as ligands, followed by a study of the structural and photophysical properties of the resulting complexes, in order to estimate and further predict the sensitization efficiencies.
In a first line of research, we have described and patented the incorporation of tetrazole groups as carboxylic acid replacements for the sensitization of lanthanide emission. We were able to show how the variation of ligand substituents influences the photophysical properties, allowing us to draw predictions and to adapt the structures for improving the emission efficiency. Some of the compounds have been successfully tested in OLED devices.
We also became interested in designing and studying new types of polymetallic architectures based on iridium complexes for the sensitization of lanthanide emission, as well as preliminary investigating the grafting of lanthanide complexes on silicon surfaces.
2016.08.15-EG_Poster_SCESv2
This document discusses research into synthesizing lanthanide catecholate complexes and their potential use in separating lanthanide elements from used nuclear fuel via electrochemical means. Specifically, it synthesized various lanthanide catechol complexes from lanthanum to europium and characterized them using cyclic voltammetry, infrared spectroscopy, and nuclear magnetic resonance spectroscopy. The results indicate binding of catechol to the lanthanide metals and differences in their electrochemical properties, demonstrating the possibility of separating lanthanides from used nuclear fuel electrochemically. This separation could reduce nuclear waste and mitigate environmental concerns with nuclear power.
Photocatalytic degradation of some organic dyes under solar light irradiation...
Photocatalytic degradation of some organic dyes under solar light irradiation...Iranian Chemical Society
Nanoparticles of the ZnO and TiO2 were synthesized and the physicochemical properties of the compounds were characterized by IR, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The XRD patterns of the ZnO and TiO2 nanoparticles could be indexed to hexagonal and rutile phase, respectively. Aggregated nanoparticles of ZnO and TiO2 with spherical-like shapes were observed with particle diameter in the range of 80-100 nm. These nanoparticles were used for photocatalytic degradation of various dyes, Rhodamine B (RhB), Methylene blue (MB) and Acridine orange (AO) under solar light irradiation at room temperature. Effect of the amount of catalyst on the rate of photodegradation was investigated. In general, because ZnO is unstable, due to incongruous dissolution to yield Zn(OH)2 on the ZnO particle surfaces and thus leading to catalyst inactivation,the catalytic activity of the system for photodegradation of dyes decreased dramatically when TiO2 was replaced by ZnO.Photocatalytic Performance of TiO2 as a Catalyst
These slides provide the information about photocatalytic performance of TiO2 as a catalyst. This slides are arranged in a systematic and logical way.
Renewable Fuels by Photocatalytic Reduction of carbondioxide (CO2); (Artifici...
This presentation contains the enhancement of photocatalytic Titania (TiO2) by Graphene, their synthesis method by solution mixing or in-situ growth and also the application for carbondioxide (CO2) reduction for renewable fuel using solar energy.
Photosynthesis Photocatalysis
The document discusses photosynthesis and photocatalysis. It provides information on:
- Photosynthesis as a natural process that occurs in chloroplasts of plant cells and some bacteria, using light, water, carbon dioxide and producing oxygen, ATP, NADPH, and sugars through the Calvin cycle.
- Photocatalysis as using light to drive catalytic chemical reactions for energy needs, including producing fuels like hydrogen and cleaning environmental pollutants. Some examples of practical applications are provided.
- Both topics are further explained through diagrams of reaction processes, and literature on artificial photosynthesis and photoelectrochemical cells is referenced.
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高分子報告
- 2. • make a new phase of carbon, called linear carbon • explosion in laboratory at Allied Chemical • injury and the end
- 3. Others persisted linear carbon is now coming closer to possible success
- 4. The story started from…. • Heeger, McDiaramid, and Shirakawa's discovery of conducting behavior in doped polyacetylene samples
- 5. Application nowadays • photovoltaic cells • field-effect transistors • chemical sensors
- 6. From Harvard University Digital Library for Physics and Astronomy • Improved photovoltaic cells and electrodes for use therein, particularly electrodes employing amorphous silicon or polyacetylene coating are produced by a process which includes …….. http://adsabs.harvard.edu/abs/1983doe..reptV....S
- 7. From Harvard University Digital Library for Physics and Astronomy • Planar and sandwich types of polyacetylene metal-semiconductor field- effect transistors (MESFETs) have been fabricated. http://nina.ecse.rpi.edu/2dfet/images/ntype2_big.gif http://adsabs.harvard.edu/abs/1991JaJAP..30.2101C
- 8. Chemical Sensor • Polyacetylene based nonlinear optical material prepared by ring-opening metathesis polymerization of cyclooctatetrene derivatives.
- 10. Unfortunately • However, Polyacetylene is thermally unstable and insoluble, making it unsuitable for general use.
- 12. Polyphenylenevinylene http://lupingyu.uchicago.edu/clip_image026.gif
- 13. Polyphenylenevinylene • Main material of Polymer Light Emitting Diode(PLED) http://www.euso.be/euso/home/images/test2.pdf
- 14. Polydiacetylenes • applications in optical limiters, waveguides, and thermometric sensors
- 15. Special properties • per-chain stiffness close to diamond • high coefficients for tripling the frequency of incoming light • negative thermal expansion coefficients tunable to near zero by introducing defects
- 16. Most Application • printed inks containing diacetylene microcrystals have been used as time- temperature indicators
- 17. Mechanism • Diacetylenes typically have an actuation energy for thermal polymerization of about 20 to 28 kcal/mol, which can be tuned to closely match the activation energy and degradation rate for important perishables
- 18. Good color indicator • Color changes of the diacetylene microcrystals during thermal polymerization provide a visual indication of whether a perishable product in the same thermal environment has degraded as a result of integrated time-temperature exposure
- 19. • Over a billion of these diacetylene polymerization-based indicators have been used on individual vaccine vials since 1996 to assist disease eradication in parts of the world that do not have a reliable cold chain
- 20. • The United States Army is using these diacetylene indicators on cartons of their MREs (Meals Ready to Eat)
- 21. Explosive compound • Though the advantages mention before, there is a problem on synthesis Polydiacetylenes • With increasing n, crystals comprising only polyynes--that is, R − (C ≡ C) n − R molecules-- become increasingly unstable, unless R is a bulky substituent group
- 22. Dangerous….. • At room temperature, it can explode if subjected to physical shock, and it decomposes slowly under ambient light, forming an insoluble material with a graphite-like appearance
- 23. Solution? • Poly(diiododiacetylene), or PIDA represents a possible solution to the general problem of polydiacetylene synthesis
- 24. Why is it? • The abundance of transition metal–catalyzed reactions available for adding substituents in place of a carbon-halogen bond makes PIDA a potential precursor to a wide variety of polydiacetylenes. • Sn2 Sn1 − δ− Nu + C X C Nu + X− δ+ δ− + δ C X C + X− − C + Nu C Nu Organic Chemistry Bruice
- 25. A complex compound • C4I2 is complexed with a specially chosen agent, an oxalamide. In these crystals, 1,4-addition polymerization of diacetylene occurs spontaneously to produce single crystals of the complexed polydiacetylene
- 26. Getting Better • The complexing agent appears to stabilize the polymerized C4I2 against explosive decomposition and eliminates the type of disorder
- 27. Disorder comes from nature • Disordered along the direction of the molecular axis. In these crystals, the alignment between adjacent monomers is random, preventing ordered polymerization
- 28. Problem caused from disorder • Obtaining the desired optical and electronic properties of a given conjugated polymer requires a highly ordered molecular structure
- 29. Way to solve the problem • if the diynes are first aligned appropriately in the solid state at a distance commensurate with the repeat distance in the target polymer, then their arrangement in space will control their reactivity, leading to ordered topochemical polymerization
- 30. Best distance • Distance of 4.9A is highly preferable for the aligned dynes with target to form highly order structure.
- 31. Conclusion • With all the efforts to make the polydiethylene mentioned before, we shall have a blueprint on how could these material be utilized and how to make it real.
- 32. • Whether or not linear carbon synthesis is practical by the poly(C4I2) route, the idea with using poly C4I2 has provided both an exciting new electronic material and a route that could lead to novel related and derivative materials.
- 33. References • Dangerously Seeking Linear Carbon Ray H. Baughman Science mag Vol. 312. no. 5776, pp. 1009 - 1110 • Preparation of Poly(diiododiacetylene), an Ordered Conjugated Polymer of Carbon and Iodine Aiwu Sun, Joseph W. Lauher, Nancy S. Goroff Vol. 312. no. 5776, pp. 1030 - 1034 • Harvard University Digital Library for Physics and Astronomy • Organic Chemistry ver 4 Bruice Original Image Source: ( Images used in this PowerPoint are modified by Stan Yang) http://stc-mditr.org/research/oeoaomd/projects/2.2.1.cfm http://nina.ecse.rpi.edu/2dfet/images/ntype2_big.gif