Use of conventional sources of energy to generate electricity is
increasing rapidly due to growing energy demands in every sector which is the major cause for pollution as well and also is an environmental concern for future. Considering this, there is lot of R&D going on in the field of alternate energy sources with recent advancements in technology. One of the recent advancement is the perovskite solar technology in the photovoltaics industry. The power conversion efficiency of perovskite solar cells has been improved from 9.7 to 20.1% within 4 years which is the fastest advancement ever in the photovoltaic industry. Such a high photovoltaic performance can be attributed to optically high absorption characteristics of the hybrid lead perovskite materials.
In this review, different perovskite materials are discussed along with the fundamental details of the hybrid lead halide perovskite materials. The fabrication techniques, stability, device structure and the chemistry of the perovskite structure are also described aiming for a better understanding of these materials and thus highly efficient perovskite solar cell devices. In addition some advantages and drawbacks are also discussed here to outline the prospects and challenges of using the perovskites in commercial PV devices.
Use of conventional sources of energy to generate electricity is
increasing rapidly due to growing energy demands in every sector which is the major cause for pollution as well and also is an environmental concern for future. Considering this, there is lot of R&D going on in the field of alternate energy sources with recent advancements in technology. One of the recent advancement is the perovskite solar technology in the photovoltaics industry. The power conversion efficiency of perovskite solar cells has been improved from 9.7 to 20.1% within 4 years which is the fastest advancement ever in the photovoltaic industry. Such a high photovoltaic performance can be attributed to optically high absorption characteristics of the hybrid lead perovskite materials.
In this review, different perovskite materials are discussed along with the fundamental details of the hybrid lead halide perovskite materials. The fabrication techniques, stability, device structure and the chemistry of the perovskite structure are also described aiming for a better understanding of these materials and thus highly efficient perovskite solar cell devices. In addition some advantages and drawbacks are also discussed here to outline the prospects and challenges of using the perovskites in commercial PV devices.
Advantages and problems of perovskite solar cellalfachemistry
This article mainly introduces the advantages and problems of perovskite solar cell. Visit https://www.alfa-chemistry.com/products/perovskite-solar-cells-139.htm for more information.
Boosting Photocatalytic Activity Using Carbon Nitride Based 2D/2D van der Waa...Pawan Kumar
The surging demand for energy and staggering pollutants in the environment have geared the scientific community to explore sustainable pathways that are economically feasible and environmentally compelling. In this context, harnessing solar energy using semiconductor materials to generate charge pairs to drive photoredox reactions has been envisioned as a futuristic approach. Numerous inorganic crystals with promising nanoregime properties investigated in the past decade have yet to demonstrate practical application due to limited photon absorption and sluggish charge separation kinetics. Two-dimensional semiconductors with tunable optical and electronic properties and quasi-resistance-free lateral charge transfer mechanisms have shown great promise in photocatalysis. Polymeric graphitic carbon nitride (g-C3N4) is among the most promising candidates due to fine-tuned band edges and the feasibility of optimizing the optical properties via materials genomics. Constructing a two-dimensional (2D)/2D van der Waals (vdW) heterojunction by allies of 2D carbon nitride sheets and other 2D semiconductors has demonstrated enhanced charge separation with improved visible photon absorption, and the performance is not restricted by the lattice matching of constituting materials. With the advent of new 2D semiconductors over the recent past, the 2D/2D heterojunction assemblies are gaining momentum to design high performance photocatalysts for numerous applications. This review aims to highlight recent advancements and key understanding in carbon nitride based 2D/2D heterojunctions and their applications in photocatalysis, including small molecules activation, conversion, and degradations. We conclude with a forward-looking perspective discussing the key challenges and opportunity areas for future research.
Pd-Substituted (La,Sr)CrO3 for Solid Oxide Fuel Cell AnodesEmmaReneeDutton
Presentation of independent honors research thesis (June 2011) for Bachelor of Science in Materials Science & Engineering at Northwestern University.
Perovskite: introduction, classification, structure of perovskite, method to synthesis, characterization by XRD and UV- vis spectroscopy , lambert beer's law, material properties and advantage and application.
An introduction of perovskite solar cellsalfachemistry
This article introduces the development, structure and work mechanism of perovskite solar cells. Visit https://www.alfa-chemistry.com/products/perovskite-solar-cells-139.htm for more information.
Recent progress in non platinum counter electrode materials for dye sensitize...Science Padayatchi
Dye-sensitized solar cells (DSSCs) have gained increasing attention
with regard to photovoltaic devices, because of their low
cost and simple fabrication methods; they are mostly investigated
in indoor light-harvesting and portable applications. The
focus has been on three main parameters of photovoltaic devices,
that is, lifetime, and cost effectiveness. A DSSC consists of
four prominent components including a photoanode, a photosensitizer,
a redox electrolyte, and a counter electrode. The
counter electrode is a crucial component, in which triiodide is
reduced to iodide by electrons flowing through the external
circuit. An effective approach to improve the performance of
a counter electrode is to enhance the power conversion efficiency
and to reduce the cost of the device. Platinum-coated
conducting glass electrodes give the best performance, but
their high cost and the scarcity of platinum restricts large-scale
application in DSSCs. This has prompted researchers to develop
low-costing platinum-free electrodes for DSSCs. In this
review, we focus mainly on counter electrode materials for the
electrocatalytic redox reaction for the I¢/I¢
3 electrolyte, and
apart from this, other counter electrode materials for iodinefree
redox electrolytes are discussed. Different counter electrode
materials are highlighted in different categories such as
carbon materials, conducting polymers, oxide and sulfide materials,
transition-metal nitrides and carbides, and composite
materials. The stability of counter electrodes in DSSCs is also
presented.
Photo-assisted oxidation of thiols to disulfides using cobalt ‘‘Nanorust’’ un...Pawan Kumar
Heterogeneous ‘‘Nanorust’’ containing cobalt oxide has been developed for the visible light assisted
oxidation of thiols to disulfides using molecular oxygen as an oxidant under alkaline free conditions and
therefore more environmentally friendly. Pyrolysis of heterogenized tetrasulfonated cobalt(II) phthalocyanine
(CoPcS) supported on mesoporous ceria (CeO2) transforms it into a novel heterogeneous ‘‘Nanorust’’
containing CoOx-C,N@CeO2 which exhibited higher catalytic activity than the homogeneous CoPcS as well
as the ceria immobilized CoPcS catalyst. Importantly, these catalysts could easily be recovered and recycled
for several runs, which makes the process greener and cost-effective.
V mn-mcm-41 catalyst for the vapor phase oxidation of o-xylenesunitha81
The role of V and Mn incorporated mesoporous molecular sieves was
investigated for the vapor phase oxidation of o-xylene. Mesoporous monometallic
V-MCM-41 (Si/V = 25, 50, 75 and 100), Mn-MCM-41 (Si/Mn = 50) and bimetallic
V-Mn-MCM-41 (Si/(V ? Mn) = 100) molecular sieves were synthesized by
a direct hydrothermal (DHT) process and characterized by various techniques such
as X-ray diffraction, DRUV-Vis spectroscopy, EPR, and transmission electron
microscopy (TEM). From the DRUV-Vis and EPR spectral study, it was found that
most of the V species are present as vanadyl ions (VO2?) in the as-synthesized
catalysts and as highly dispersed V5? ions in tetrahedral coordination in the calcined
catalysts. The activity of the catalysts was measured and compared with each other
for the gas phase oxidation of o-xylene in the presence of atmospheric air as an
oxidant at 573 K. Among the various catalysts, V-MCM-41 with Si/V = 50
exhibited high activity towards production of phthalic anhydride under the experimental
condition. The correlation between the phthalic anhydride selectivity and
the physico-chemical characteristics of the catalyst was found. It is concluded that
V5? species present in the MCM-41 silica matrix are the active sites responsible for
the selective formation of phthalic anhydride during the vapor phase oxidation of
o-xylene.
Heterostructured nanocomposite tin phthalocyanine@mesoporous ceria (SnPc@CeO2...Pawan Kumar
Heterostructured tin phthalocyanine supported to mesoporous ceria was synthesized and used a
photocatalyst for CO2 reduction under visible light. The photoreduction CO2 activities of the
heterostructures were investigated in the presence of triethylamine as sacrificial agent. The developed
photocatalyst exhibited high catalytic activity for photoreduction of CO2 and after 24 hours of visible
light irradiation 2342 mmol g1 cat of methanol (fMeOH ¼ 0.0223 or 2.23%) and 840 mmol g1 cat of CO
(fCO ¼ 0.0026 or 0.26%) were obtained as the major reaction products. The methanol formation rate
(RMeOH) and CO formation rate (RCO) was found to be 97.5 mmol h1 g1 cat and 35.0 mmol h1 g1 cat
respectively. While under the identical experimental conditions mesoporous ceria (meso-CeO2) gave
only 316 mmol g1 cat of methanol (fMeOH ¼ 0.003 or 0.30%) and 126 mmol g1 cat CO (fCO ¼ 0.0004
or 0.04%) with product formation rate RMeOH ¼ 13.2 mmol h1 g1 cat and RCO ¼ 5.3 mmol h1 g1 cat.
Furthermore, the recovered catalyst showed consistent catalytic activity for at least five runs without any
significant loss in product yields
SOFC is like a battery but better: Solution for every Automakers. Fuel cell is an electro chemical cell in which chemical energy of fuel is directly converted into electrical energy.
Device simulation of perovskite solar cells with molybdenum disulfide as acti...journalBEEI
Organo-halide Perovskite Solar Cells (PSC) have been reported to achieve remarkably high power conversion efficiency (PCE). A thorough understanding of the role of each component in solar cells and their effect as a whole is still required for further improvement in PCE. In this paper, the effect of Molybdenum Disulfide (MoS2) in PSC with mesoporous structure configuration was analyzed using Solar Cell Capacitance Simulator (SCAPS). With the MoS2 layer which having two-fold function, acting as a protective layer, by preventing the formation of shunt contacts between perovskite and Au electrode, and as a hole transport material (HTM) from the perovskite to the Spiro-OMETAD. As simulated, PSC demonstrates a PCE, ŋ of 13.1%, along with stability compared to typical structure of PSC without MoS2 (Δ ŋ/ŋ=-9% vs. Δ ŋ/ŋ=-6%). The results pave the way towards the implementation of MoS2 as a material able to boost shelf life which very useful for new material choice and optimization of HTMs
Nanostructured composite materials for CO2 activationPawan Kumar
The increasing energy crisis and the worsening global climate caused by the excessive
utilization of the fossil fuel have boosted tremendous research about CO2 capture, storage and
utilization. Among these approaches, utilization of carbon dioxide to produce valuable chemicals
is preferred than dumping it. Particularly, utilization of CO2 as feedstock for the photocatalytic
conversion into valuable products is a viable approach for harvesting solar radiation as an energy
source and to mitigate increasing CO2 concentration. Artificial photosynthesis by using
nanostructured materials as photocatalyst has immense potential to convert carbon dioxide into
renewable fuels such as methanol/CO etc. The present chapter focuses on the synthesis, characterization and application of various nanostructured materials for CO2 activation including
photoreduction of CO2 to valuable products.
Advantages and problems of perovskite solar cellalfachemistry
This article mainly introduces the advantages and problems of perovskite solar cell. Visit https://www.alfa-chemistry.com/products/perovskite-solar-cells-139.htm for more information.
Boosting Photocatalytic Activity Using Carbon Nitride Based 2D/2D van der Waa...Pawan Kumar
The surging demand for energy and staggering pollutants in the environment have geared the scientific community to explore sustainable pathways that are economically feasible and environmentally compelling. In this context, harnessing solar energy using semiconductor materials to generate charge pairs to drive photoredox reactions has been envisioned as a futuristic approach. Numerous inorganic crystals with promising nanoregime properties investigated in the past decade have yet to demonstrate practical application due to limited photon absorption and sluggish charge separation kinetics. Two-dimensional semiconductors with tunable optical and electronic properties and quasi-resistance-free lateral charge transfer mechanisms have shown great promise in photocatalysis. Polymeric graphitic carbon nitride (g-C3N4) is among the most promising candidates due to fine-tuned band edges and the feasibility of optimizing the optical properties via materials genomics. Constructing a two-dimensional (2D)/2D van der Waals (vdW) heterojunction by allies of 2D carbon nitride sheets and other 2D semiconductors has demonstrated enhanced charge separation with improved visible photon absorption, and the performance is not restricted by the lattice matching of constituting materials. With the advent of new 2D semiconductors over the recent past, the 2D/2D heterojunction assemblies are gaining momentum to design high performance photocatalysts for numerous applications. This review aims to highlight recent advancements and key understanding in carbon nitride based 2D/2D heterojunctions and their applications in photocatalysis, including small molecules activation, conversion, and degradations. We conclude with a forward-looking perspective discussing the key challenges and opportunity areas for future research.
Pd-Substituted (La,Sr)CrO3 for Solid Oxide Fuel Cell AnodesEmmaReneeDutton
Presentation of independent honors research thesis (June 2011) for Bachelor of Science in Materials Science & Engineering at Northwestern University.
Perovskite: introduction, classification, structure of perovskite, method to synthesis, characterization by XRD and UV- vis spectroscopy , lambert beer's law, material properties and advantage and application.
An introduction of perovskite solar cellsalfachemistry
This article introduces the development, structure and work mechanism of perovskite solar cells. Visit https://www.alfa-chemistry.com/products/perovskite-solar-cells-139.htm for more information.
Recent progress in non platinum counter electrode materials for dye sensitize...Science Padayatchi
Dye-sensitized solar cells (DSSCs) have gained increasing attention
with regard to photovoltaic devices, because of their low
cost and simple fabrication methods; they are mostly investigated
in indoor light-harvesting and portable applications. The
focus has been on three main parameters of photovoltaic devices,
that is, lifetime, and cost effectiveness. A DSSC consists of
four prominent components including a photoanode, a photosensitizer,
a redox electrolyte, and a counter electrode. The
counter electrode is a crucial component, in which triiodide is
reduced to iodide by electrons flowing through the external
circuit. An effective approach to improve the performance of
a counter electrode is to enhance the power conversion efficiency
and to reduce the cost of the device. Platinum-coated
conducting glass electrodes give the best performance, but
their high cost and the scarcity of platinum restricts large-scale
application in DSSCs. This has prompted researchers to develop
low-costing platinum-free electrodes for DSSCs. In this
review, we focus mainly on counter electrode materials for the
electrocatalytic redox reaction for the I¢/I¢
3 electrolyte, and
apart from this, other counter electrode materials for iodinefree
redox electrolytes are discussed. Different counter electrode
materials are highlighted in different categories such as
carbon materials, conducting polymers, oxide and sulfide materials,
transition-metal nitrides and carbides, and composite
materials. The stability of counter electrodes in DSSCs is also
presented.
Photo-assisted oxidation of thiols to disulfides using cobalt ‘‘Nanorust’’ un...Pawan Kumar
Heterogeneous ‘‘Nanorust’’ containing cobalt oxide has been developed for the visible light assisted
oxidation of thiols to disulfides using molecular oxygen as an oxidant under alkaline free conditions and
therefore more environmentally friendly. Pyrolysis of heterogenized tetrasulfonated cobalt(II) phthalocyanine
(CoPcS) supported on mesoporous ceria (CeO2) transforms it into a novel heterogeneous ‘‘Nanorust’’
containing CoOx-C,N@CeO2 which exhibited higher catalytic activity than the homogeneous CoPcS as well
as the ceria immobilized CoPcS catalyst. Importantly, these catalysts could easily be recovered and recycled
for several runs, which makes the process greener and cost-effective.
V mn-mcm-41 catalyst for the vapor phase oxidation of o-xylenesunitha81
The role of V and Mn incorporated mesoporous molecular sieves was
investigated for the vapor phase oxidation of o-xylene. Mesoporous monometallic
V-MCM-41 (Si/V = 25, 50, 75 and 100), Mn-MCM-41 (Si/Mn = 50) and bimetallic
V-Mn-MCM-41 (Si/(V ? Mn) = 100) molecular sieves were synthesized by
a direct hydrothermal (DHT) process and characterized by various techniques such
as X-ray diffraction, DRUV-Vis spectroscopy, EPR, and transmission electron
microscopy (TEM). From the DRUV-Vis and EPR spectral study, it was found that
most of the V species are present as vanadyl ions (VO2?) in the as-synthesized
catalysts and as highly dispersed V5? ions in tetrahedral coordination in the calcined
catalysts. The activity of the catalysts was measured and compared with each other
for the gas phase oxidation of o-xylene in the presence of atmospheric air as an
oxidant at 573 K. Among the various catalysts, V-MCM-41 with Si/V = 50
exhibited high activity towards production of phthalic anhydride under the experimental
condition. The correlation between the phthalic anhydride selectivity and
the physico-chemical characteristics of the catalyst was found. It is concluded that
V5? species present in the MCM-41 silica matrix are the active sites responsible for
the selective formation of phthalic anhydride during the vapor phase oxidation of
o-xylene.
Heterostructured nanocomposite tin phthalocyanine@mesoporous ceria (SnPc@CeO2...Pawan Kumar
Heterostructured tin phthalocyanine supported to mesoporous ceria was synthesized and used a
photocatalyst for CO2 reduction under visible light. The photoreduction CO2 activities of the
heterostructures were investigated in the presence of triethylamine as sacrificial agent. The developed
photocatalyst exhibited high catalytic activity for photoreduction of CO2 and after 24 hours of visible
light irradiation 2342 mmol g1 cat of methanol (fMeOH ¼ 0.0223 or 2.23%) and 840 mmol g1 cat of CO
(fCO ¼ 0.0026 or 0.26%) were obtained as the major reaction products. The methanol formation rate
(RMeOH) and CO formation rate (RCO) was found to be 97.5 mmol h1 g1 cat and 35.0 mmol h1 g1 cat
respectively. While under the identical experimental conditions mesoporous ceria (meso-CeO2) gave
only 316 mmol g1 cat of methanol (fMeOH ¼ 0.003 or 0.30%) and 126 mmol g1 cat CO (fCO ¼ 0.0004
or 0.04%) with product formation rate RMeOH ¼ 13.2 mmol h1 g1 cat and RCO ¼ 5.3 mmol h1 g1 cat.
Furthermore, the recovered catalyst showed consistent catalytic activity for at least five runs without any
significant loss in product yields
SOFC is like a battery but better: Solution for every Automakers. Fuel cell is an electro chemical cell in which chemical energy of fuel is directly converted into electrical energy.
Device simulation of perovskite solar cells with molybdenum disulfide as acti...journalBEEI
Organo-halide Perovskite Solar Cells (PSC) have been reported to achieve remarkably high power conversion efficiency (PCE). A thorough understanding of the role of each component in solar cells and their effect as a whole is still required for further improvement in PCE. In this paper, the effect of Molybdenum Disulfide (MoS2) in PSC with mesoporous structure configuration was analyzed using Solar Cell Capacitance Simulator (SCAPS). With the MoS2 layer which having two-fold function, acting as a protective layer, by preventing the formation of shunt contacts between perovskite and Au electrode, and as a hole transport material (HTM) from the perovskite to the Spiro-OMETAD. As simulated, PSC demonstrates a PCE, ŋ of 13.1%, along with stability compared to typical structure of PSC without MoS2 (Δ ŋ/ŋ=-9% vs. Δ ŋ/ŋ=-6%). The results pave the way towards the implementation of MoS2 as a material able to boost shelf life which very useful for new material choice and optimization of HTMs
Nanostructured composite materials for CO2 activationPawan Kumar
The increasing energy crisis and the worsening global climate caused by the excessive
utilization of the fossil fuel have boosted tremendous research about CO2 capture, storage and
utilization. Among these approaches, utilization of carbon dioxide to produce valuable chemicals
is preferred than dumping it. Particularly, utilization of CO2 as feedstock for the photocatalytic
conversion into valuable products is a viable approach for harvesting solar radiation as an energy
source and to mitigate increasing CO2 concentration. Artificial photosynthesis by using
nanostructured materials as photocatalyst has immense potential to convert carbon dioxide into
renewable fuels such as methanol/CO etc. The present chapter focuses on the synthesis, characterization and application of various nanostructured materials for CO2 activation including
photoreduction of CO2 to valuable products.
Fabrication and characterization of printed zinc batteriesjournalBEEI
Zinc batteries are a more sustainable alternative to lithium-ion batteries due to its components being highly recyclable. With the improvements in the screen printing technology, high quality devices can be printed with at high throughput and precision at a lower cost compared to those manufactured using lithographic techniques. In this paper we describe the fabrication and characterization of printed zinc batteries. Different binder materials such as polyvinyl pyrrolidone (PVP) and polyvinyl butyral (PVB), were used to fabricate the electrodes. The electrodes were first evaluated using three-electrode cyclic voltammetry, x-ray diffraction (XRD), and scanning electron microscopy before being fully assembled and tested using charge-discharge test and two-electrode cyclic voltammetry. The results show that the printed ZnO electrode with PVB as binder performed better than PVP-based ZnO. The XRD data prove that the electro-active materials were successfully transferred to the sample. However, based on the evaluation, the results show that the cathode electrode was dominated by the silver instead of Ni(OH)2, which leads the sample to behave like a silver-zinc battery instead of a nickel-zinc battery. Nevertheless, the printed zinc battery electrodes were successfully evaluated, and more current collector materials for cathode should be explored for printed nickel-zinc batteries.
Zno and znopbs heterojunction photo electrochemical cellseSAT Journals
Abstract Photo Electrochemical Cell (PEC) can also be used for splitting of water into hydrogen and Oxygen. Here, ZnO nanorod PEC has been prepared in hydrothermal method and ZnO/PbS quantum dot PEC has been prepared by hydrothermal method and chemical bath deposition method. UV-Visible spectroscopy has been observed. Flat band voltage, bandwidth and majority charge carriers have been calculated from Mott-Schottky. Impedance variation at semiconductor and electrolyte junction has been observed with Electrochemical Impedance Spectroscopy (EIS). Keywords: Hydrothermal, Chemical bath, ZnO/PbS, UV-Vis, Mott-Schottky, EIS.
TiO2-HfN Radial Nano-Heterojunction: A Hot Carrier Photoanode for Sunlight-Dr...Pawan Kumar
The lack of active, stable, earth-abundant, and visible-light absorbing materials to replace
plasmonic noble metals is a critical obstacle for researchers in developing highly efficient and costeffective photocatalytic systems. Herein, a core–shell nanotube catalyst was fabricated consisting of
atomic layer deposited HfN shell and anodic TiO2 support layer with full-visible regime photoactivity
for photoelectrochemical water splitting. The HfN active layer has two unique characteristics: (1) a
large bandgap between optical and acoustic phonon modes (2) and no electronic bandgap, which
allows a large population of long life-time hot carriers, which are used to enhance the photoelectrochemical performance. The photocurrent density (≈2.5 mA·cm−2 at 1 V vs. Ag/AgCl) obtained in
this study under AM 1.5G 1 Sun illumination is unprecedented, as it is superior to most existing
plasmonic noble metal-decorated catalysts and surprisingly indicates a photocurrent response that
extends to 730 nm. The result demonstrates the far-reaching application potential of replacing active
HER/HOR noble metals such as Au, Ag, Pt, Pd, etc. with low-cost plasmonic ceramics.
Electrochemical Investigation of Electrolyte & Anodic Materials for Sodium Io...CrimsonPublishersRDMS
Electrochemical Investigation of Electrolyte & Anodic Materials for Sodium Ion Batteries by Majid Monajjemi* in Crimson Publishers: Peer Reviewed Material Science Journals
Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
NO1 Uk best vashikaran specialist in delhi vashikaran baba near me online vas...Amil Baba Dawood bangali
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1. Research statement
August 16, 2015
(This article is based on what was posted on January 30, 2015, for Linkedin)
Toru Hara, PhD
Quest for Ultimate Energy Storage Device
1. Introduction and background
With supercapacitor-like rate capability and battery-like energy density, the energy storage
device can be the ultimate "one."
For the better rate capability, it is possibly known that the ideal electrode architecture is
three-dimensionally (3D) interpenetrated electron/ion network leading to efficient ion and electron
transport [1, 2]. For the higher energy density, active materials for batteries are formed in the 3D
architecture: Zhang et al. used electrodeposition to form NiOOH (cathode for nickel metal hydride
battery) and MnO2 (cathode for lithiµm-ion battery) electrodes directly onto 3D nickel current
collectors [3].
Battery that works in water-based (aqueous) electrolyte solutions, such as nickel metal
hydride batteries, has some advantages: (1) it does not need an inert atmosphere for manufacturing
unlike lithiµm-ion batteries thereby offering low cost; (2) it does not use flammable electrolyte
solutions unlike lithiµm-ion batteries thereby unlike lithiµm-ion batteries it does not catch a fire.
In contrast, the merit of lithiµm-ion batteries that work in organic electrolyte solutions is, they can
deliver higher output voltage because of greater electrochemical windows thereby offering high
energy density. So far the market seeking smaller and lighter batteries has been driving economy,
i.e., consumer electronics and lithiµm-ion batteries. From now onward, it is said that
environmental-protection-driven (= or energy-sustainability-driven) or security-of-materials-
driven (in a broad meaning) may drive economy. This may shed light on aqueous batteries,
particularly non-lithiµm-ion batteries: lithiµm is not abundant compared with sodium, proton, etc.
From this point of view, aqueous batteries with 3D-architectured electrodes, particularly Na+ or
H+ ion batteries can be promising.
2. Mono-atomic layer FeOOH / NiOOH battery
Among many candidates materials combinations, I have chosen (-) FeOOH / NiOOH (+).
The novelty is forming mono-atomic layers of FeOOH and NiOOH. The main objective is to elude
the beta-MOOH -> gamma-MOOH <-> alpha-M(OH)2 -> beta-M(OH)2 <-> beta-MOOH loop [M
= Fe, Ni] that can result in crystal structure destruction during charge/discharge. The phase change
is just a matter of the stacking pattern change [4]; the mono-atomic FeOOH and NiOOH layers
have no MOOH stacking thereby they can offer a long cycle life.
2. 2.1. FeOOH / NiOOH battery chemistry
At the anode (negative electrode) the following reaction takes place:
FeOOH + H+ + e- <-> Fe(OH)2, -0.56 V vs. SHE,
here, SHE denotes standard hydrogen electrode. Theoretical capacity is 301 mAh/g (470 mAh/g
is possible when overdischarged). Note that hydrogen evolution reaction can happen at -0.83 V vs.
SHE at pH = 14; thus, this side reaction can be suppressed even the anode is somewhat
overdischarged.
At the cathode (positive electrode) the following reaction takes place:
NiOOH + H+ +e- <-> Ni(OH)2, +0.49 V vs. SHE
Theoretical capacity is 292 mAh/g (467 mAh/g is possible when overcharged but usually
accompanying oxygen evolution side reaction). Note that oxygen evolution reaction can happen
at 0.4 V vs. SHE at pH = 14 although the overpotential of the reaction may be expected to some
extent.
The full cell reaction becomes
NiOOH + Fe(OH)2 <-> Ni(OH)2 + FeOOH, Ecell = 1.05 V.
This battery eliminates a slow reaction of the conventional NiFe battery reaction: that is
2NiOOH + Fe + 2H2O <-> 2Ni(OH)2 + Fe(OH)2, Ecell = 1.37 V. This battery only uses the second
reaction of the conventional NiFe battery: NiOOH + Fe(OH)2 <-> Ni(OH)2 + FeOOH, Ecell = 1.05
V. Recently, many researchers are trying to use nanosized iron oxide as the anode instead of metal
iron, e.g., Fe2O3 [5] or Fe3O4 [6]; however, the redox reactions via iron oxides tend to be
irreversible or slow.
2.2. 3D interpenetrated electron/ion network for mono-atomic layer FeOOH / NiOOH battery
In order to form 3D interpenetrated electron/ion network, 3D current collector can be used.
There are various types of 3D current collectors; among them graphene paper is a promising
candidate. Suppose 30 mg/cm2 (corresponding to 9 mAh/cm2) of FeOOH is directly deposited onto
current collectors:
(1) metal foil, surface area =1.0 cm2 (real)/cm2 (nominal), FeOOH thickness = 211 µm;
(2) carbon fiber paper [e.g., TGP-H-60 (Toray Industry Inc., 190-μm thick)], surface area = 33.4
cm2 (real)/cm2 (nominal), FeOOH thickness = 6.3 µm;
(3) activated carbon fiber paper (e.g., 190-µm thick), surface area = 3 340 cm2 (real)/cm2 (nominal),
FeOOH thickness = 63 nm;
3. (4) carbon-fiber-paper-supported carbon nanofoam (e.g., 190-µm thick); surface area = 64 000
cm2 (real)/cm2 (nominal), FeOOH thickness = 3.3 nm;
(5) graphene paper (e.g., 200-µm thick), surface area = 2630 m2/g x 16 mg/cm2 = 420 800 cm2
(real)/cm2 (nominal), FeOOH thickness = 0.50 nm;
(6) reduced graphene oxide & carbon nanotube paper [7], surface area = 651 m2/g x 16 mg/cm2
(supposing a thickness of around 200 µm) = 104 160 cm2 (real)/cm2 (nominal), FeOOH thickness
= 2.0 nm.
There can be a less expensive 3D current collector: (i) starting from Ni foam, NiSn intermetallic
layer is electrodeposited onto theNi foam; (ii) next, Sn is dissolved into alkaline solution,
remaining porous Ni layer.
2.3. FeOOH- and NiOOH-forming onto 3D current collector
There are two options regarding the FeOOH- and NiOOH-forming process, chemical
synthesis and electrodeposition. I have chosen electrodeposition.
Particularly when using graphene, chemical synthesis tends to result in a dot-on-graphene
structure or a multi-atomic MOOH layer [8,9]. Electrodeposition is promising even though mono-
atomic layer formation has not been reported so far [3, 10-13]. Particularly, pulse electrodeposition
at a high current density is preferable.
2.4. Electron (or hole) conductivity of FeOOH and NiOOH
The reduced forms of active materials, M(OH)2 are highly insulating: Ni 3d-t2g orbitals are
relatively well hybridized with O 2p orbitals; however, it is not the case with Fe 3d-eg orbitals.
Thus mono-atomic thick MOOH is preferable particularly for FeOOH.
2.5. Other anode materials choices
Besides NiFe battery, NiOOH cathode has been used with various types of anode materials
such as Zn, Cd, metal hydride, etc.
As for Zn anode, the current problems are inefficient zinc utilization and internal short
circuit failure resulting from zinc dendrite formation. In order to improve zinc utilization and to
suppress zinc dendrite formation, a redesign of zinc electrode will be required, i.e., a porous,
monolithic, 3D aperiodic architecture [14, 15]: according to the authors of refs. 14 and 15, the
redesigned Zn sponge electrode provides (i) an inner core of Zn that is retained throughout battery
charge/discharge to facilitate long-range electronic conductivity, (ii) amplification of electrified
interfaces to distribute current uniformly throughout the electrode structure, and thus eliminate
dendrite forming high current densities, and (iii) confined void volume elements within the interior
of the porous anode that expedite saturation/dehydration of zincate to ZnO, thus preventing shape
4. change. However, the Zn sponge electrode may be difficult for scaling up electrode size. The same
functions can be offered by directly electrodepositing Zn onto 3D current collector (I already
initiated one R&D project on Zn/NiOOH battery).
Cadmium is not a choice because of its toxicity.
Metal hydride may survive: Kawasaki Heavy Indutry delivers 30-year-life nickel metal
hydride battery, Gigacell.
Zn still has a strength regarding its energy density: it delivers the most negative potential
and the highest theoretical capacity among anode materials that can be used in aqueous media.
Note that NiZn battery is a hybrid ion system (Zn2+ and H+) like Leclanche cell or alkaline
manganese cell.
There may be other choices.
Vanadium oxide may not be a choice since it is lethally toxic.
MoO3 is not cheap and the supply can be restricted. Molybdenum, country of origin: 1.
China (104 000 ton/year), 2. USA (60 400), 3. Chile (35 090), 4. Peru (16 790), 5. Mexico (11
000) up, 6. Canada (9 005), 7. Iran (6 300), 8. Turkey (5 000), 9. Armenia (4 900), 10. Russia
(3,900), 11. Mongol (1,903), 12. Uzbekistan (550). Molybdenum, amount of deposit: 1. China (4
300 000 ton), 2. USA (2 700 000), 3. Chile (1 100 000), 4. Peru (450 000), 5. Russia (250 000), 6.
Armenia (200 000), 7. Canada (200 000), 8. Mongol (160 000), 9. Mexico (130 000), 10.
Kazakhstan (130 000), 11. Kyrgystan (100 000), 12. Uzbekistan (60 000), 13. Iran (50 000).
Uneven distribution of countries of origin has often generated international friction. In addition,
molybdenum is a key material for various types of specialty steel. The omnipresence of raw
materials is one of key requirements for supplying cheap batteries.
Surface-modified carbon-based materials such as HNO3 treated carbon nanotubes and/or
graphene oxide can be candidate alternatives. In order to re-obtain the electronic conductivity of
above-mentioned carbonaceous materials, a mild reduction process (resulting in O content = 10-
15%) such as a heat treatment at 200-250 degrees Celsius in an inert atmosphere is preferable than
harsh chemical reduction processes since oxygen-based functional groups are required in order to
obtain a high capacity in aqueous media. However, gravimetric capacities of the above-mentioned
materials tend to be not high enough. It has been known that Russian companies, ELTON (ESMA),
delivers asymmetric electrochemical capacitors, (-) activated carbon / NiOOH (+): carbon
nanotube- or graphene-based materials can be good alternatives for activated carbon.
2.6. Other cathode materials choices
In Leclanche cells and alkaline manganese cells, MnO2 is used as the cathode material (I
prefer the expression, MnOOH, since I consider that it should be clearly described as a proton
intercalation/deintercalation material). The problems are a relatively low gravimetric capacity
(usually 100-150 mAh/g is available) and dissolution into aqueous media because of the multi-
5. valency of manganese. It is noteworthy that MnO2 can be directly electrodeposited onto current
collectors [3].
3. Practical issues
3.1. Oxygen evolution at NiOOH cathode
While charging, oxygen gas may evolve at the NiOOH cathode. The overpotential of
oxygen evolution at pure NiOOH electrode can be +0.23 V in 1 M KOH solution at 10 mA/cm2
[16,17], for example. Since the electrical conductivity of Ni(OH)2/NiOOH is not high (101 - 106
Ω/cm) [18-21] (cf. FeOOH, 105 - 107 Ω/cm [22,23]), thick NiOOH films tend to suffer from
overlap of its redox potential with oxygen evolution potential because of a high internal resistance
(therefore, hole doping such as Co2+/3+ doping is often carried out); however, it is not the case with
mono-atomic layer NiOOH on graphene sheet. Instead, the pH of electrolyte solution (by
decreasing the concentration of KOH, oxygen evolution potential becomes more positive thereby
oxygen cannot start evolving until reaching a more positive potential.), a relatively low oxygen
evolution overpotential at a low current (meaning that oxygen starts evolving at a less positive
potential when the battery is operated at a low C-rate) must be taken into consideration.
Although I am not going to dope Co2+/3+ into NiOOH for this mono-atomic layer FeOOH
/ NiOOH battery, it might be interesting to investigate the doping effect on the mono-atomic layer
NiOOH or FeOOH when considering the electron/hole conduction modulation by internal
hole/electron doping and by ad-atom or ad-ion surface doping [24-27].
3.2. Electrochemical impedance spectroscopy (EIS)
Since mono-atomic layer FeOOH / NiOOH battery has a great surface area particularly
when deposited onto graphene paper, thereby has a great capacity (the response speed limit may
still be a mere 1000 C corresponding to 0.36 s, though), and since a few layers of graphene and
FeOOH or NiOOH can have a so-called quantum capacitance (In addition, graphene oxide,
FeOOH, and NiOOH may exhibit current relaxation that is related to charge trapping/detrapping
into/from defective states or their genuine 3d orbitals [28-30]: this relaxation is also a redox
reaction.), I may not recommend EIS to explore the underlying rate-determining step(s) because
of its high CR time constant etc. [C denotes capacitance that is the sum of electrical double layer
capacitance and pseudo-capacitance, R denotes series equivalent resistance (SER)] (Note that SER
does not mean DC resistance or a resistance at the lowest frequency; if one wants to analyze charge
transfer process etc., one must use the impedance value at the intersection with the real axis.).
4. Future prospects
6. Considering the possibility of 9 mAh/cm2 with an electrode thickness of 200 µm (assuming
a mass-loading of 30 mg/cm2), the mono-atomic layer FeOOH/NiOOH battery deposited onto 3D
graphene papers can be competitive enough with lithium-ion batteries that usually offers around
2.5 mAh/cm2 with an electrode thickness of 100 µm although its output voltage of 1 V is lower
than that of lithium-ion batteries, 3.6 V. Furthermore, eluding the β-MOOH -> γ-MOOH <-> α-
M(OH)2 -> β-M(OH)2 <-> β-MOOH loop [M = Fe, Ni] [4] by forming mono-atomic layer can
lead to a super long cycle life that has not been realized: this can be called a 0.5-step beyond the
cutting edge.
However, a practical compromise or a 1-step-beyond-the-cutting-edge technology may be
required since conventional batteries performance has been improved year by year.
4.1. Compromise for increasing volumetric capacity
In order to increase the volumetric capacity, a few to several atomic layer thick FeOOH
and NiOOH electrodes may be preferred.
4.2. One step beyond the cutting edge
By taking full advantage of the 3D architecture and the combination of mono-atomic layer
active materials, even all-solid-state energy storage device with a practically high enough
capacity/pseudo-capacitance may be possible. In that case, redox reactions should be re-considered
the current relaxation that is charge trapping/detrapping into/from defective states or genuine 3d
orbitals [28-30] etc.
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