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Inorganic Nanocrystal Photocatalysts For Solar Energy Conversion
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Book Synopsis Inorganic Metal Oxide Nanocrystal Photocatalysts for Solar Fuel Generation from Water by : Troy K. Townsend
Download or read book Inorganic Metal Oxide Nanocrystal Photocatalysts for Solar Fuel Generation from Water written by Troy K. Townsend and published by Springer Science & Business Media. This book was released on 2014-03-19 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: Troy Townsend's thesis explores the structure, energetics and activity of three inorganic nanocrystal photocatalysts. The goal of this work is to investigate the potential of metal oxide nanocrystals for application in photocatalytic water splitting, which could one day provide us with clean hydrogen fuel derived from water and solar energy. Specifically, Townsend's work addresses the effects of co-catalyst addition to niobium oxide nanotubes for photocatalytic water reduction to hydrogen, and the first use of iron oxide 'rust' in nanocrystal suspensions for oxygen production. In addition, Townsend studies a nickel/oxide-strontium titanate nanocomposite which can be described as one of only four nanoscale water splitting photocatalysts. He also examines the charge transport for this system. Overall, this collection of studies brings relevance to the design of inorganic nanomaterials for photocatalytic water splitting while introducing new directions for solar energy conversion.
Book Synopsis Inorganic Nanocrystal Photocatalysts for Solar Energy Conversion by : Jing Zhao
Download or read book Inorganic Nanocrystal Photocatalysts for Solar Energy Conversion written by Jing Zhao and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar energy conversion is considered one of the most promising renewable energy solutions for replacing fossil fuels and easing global climate change. Developing a cost-effective technology for solar energy utilization to compete with market grid price is among the top priorities of our scientific society. Photocatalytic water splitting, which utilizes solar energy to produce carbon-zero hydrogen fuels from water, holds great potential towards achieving this challenging mission. Photovoltaic (PV) devices, for converting solar energy to electricity, continue to witness technological advances in the 21st century. This dissertation is dedicated to the advancement of photocatalytic water splitting and photovoltaic technologies, including the search for inexpensive photocatalysts with high efficiency, the fundamental understanding of photo-induced charge separation processes and the advanced instrumentation for probing photovoltage generation on the nanoscale. Chapter 2 starts off with the effect of quantum size confinement on the photocatalytic hydrogen production by CdSe nanocrystals. The particle size of a well-defined CdSe nanocrystal series is systematically varied, and their size-dependent conduction/valence band energetics as well as their photocatalytic hydrogen evolution rates are characterized in details. This allows the construction of a quantitative correlation between particle size, energy level and photocatalytic activity for CdSe nanocrystals, following Butler-Volmer electron-transfer theory. Chapter 3 transitions into the study on WO3 photoanodes for photocatalytic oxygen evolution. The activity of WO3 photoanodes is greatly enhanced via an in-situ doping by electrochemical reduction. Investigations show that the moderate reduction boosts carrier concentration and conductivity in WO3, consequently an improved charge collection and an increased photocurrent response. This activation strategy is also proven to be applicable to other WO3 systems with a wide range of particle sizes. Chapter 4 introduces surface photovoltage spectroscopy (SPS) as a powerful sensitive technique for probing photon-induced charge separation processes in photocatalysts and PV systems. Calcium niobium oxide, a wide bandgap hydrogen evolution photocatalyst with a well-defined surface morphology, is selected as a model material for understanding the photovoltage generation and charge separation in photocatalyst system via SPS. Systematic studies reveal the dependence of photovoltage on photon wavelength, light intensity, defect density, film thickness, ambient environment, substrate property, and the relative Fermi-level difference at the interface. Chapter 5 continues the application of SPS technique for understanding charge separation in CdSe nanocrystalline films for inorganic-/organic- hybrid solar cells. Surface ligands on CdSe nanocrystals are found to have a dramatic impact on the photovoltage responses from CdSe films. The replacement of native ligands by halides and amines leads to electron traps at the particle surface. Chloride, among all halide ligands, is indicated as a promising short surface ligand for good photovoltage response, whereas bromide and iodide are found as detrimental hole traps.
Book Synopsis New and Future Developments in Catalysis by : W. David Wei
Download or read book New and Future Developments in Catalysis written by W. David Wei and published by Elsevier Inc. Chapters. This book was released on 2013-07-19 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Semiconductor Solar Photocatalysts by : Jiaguo Yu
Download or read book Semiconductor Solar Photocatalysts written by Jiaguo Yu and published by John Wiley & Sons. This book was released on 2022-03-14 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides a timely overview of basic principles and significant advances of semiconductor-based photocatalysts for solar energy conversion Semiconductor Solar Photocatalysts: Fundamentals and Applications presents a systematic, in-depth summary of both fundamental and cutting-edge research in novel photocatalytic systems. Focusing on photocatalysts with vast potential for efficient utilization of solar energy, this up-to-date volume covers heterojunction systems, graphene-based photocatalysts, organic semiconductor photocatalysts, metal sulfide semiconductor photocatalysts, and graphitic carbon nitride-based photocatalysts. Organized into six chapters, the text opens with a detailed introduction to the history, design principles, modification strategies, and performance evaluation methods of solar energy photocatalysis. The remaining chapters provide detailed discussion of various novel photocatalytic systems such as direct Z-scheme and S-scheme photocatalysts, organic polymers, and covalent organic frameworks. This authoritative resource: Explains the essential concepts of solar energy photocatalysis and heterojunction systems for photocatalysis Reviews interesting structures and new applications of semiconductor photocatalysts Features contributions from an international panel of leading researchers in the field Includes extensive references and numerous tables, figures, and color illustrations Semiconductor Solar Photocatalysts: Fundamentals and Applications is valuable resource for all catalytic chemists, materials scientists, inorganic and physical chemists, chemical engineers, and physicists working in the semiconductor industry.
Book Synopsis Photochemistry of Inorganic Nanomaterials for Solar Energy Conversion by : Timothy L. Shelton
Download or read book Photochemistry of Inorganic Nanomaterials for Solar Energy Conversion written by Timothy L. Shelton and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: As our world’s population is constantly growing, so also is the need to power the growth and spread of technology. The conversion of abundant solar energy into useable sources of fuel is an area of significant and vital research. Photocatalytic water splitting via suspended nanomaterials or photoelectrochemical cells has great promise for this purpose. This research focuses on the preparation and analysis of nanomaterials utilizing simple methods and earth abundant chemicals that will lead to cost-competitive methods to convert solar energy into an easily stored and transported fuel source. Specifically, our research seeks to better understand the methods of charge generation and separation in nanomaterial films and to quantify the limits of activity in suspended photocatalysts. Chapter 2 introduces a study on the nature of photovoltage generation in well-ordered hematite films under zero applied bias. The thickness of Fe2O3 nanorod films is varied by a simple hydrothermal synthesis and confirmed with TEM and profilometry measurements. Surface photovoltage spectroscopy (SPS) in the presence of air, water, nitrogen, oxygen, and under vacuum confirms photovoltages are associated with oxidation of surface water and hydroxyl groups and with reversible surface hole trapping on the 1 minute time scale and de-trapping on the 1 hour time scale with a maximum photovoltage of -130 mW under 2.0 eV – 4.5 eV illumination. Sacrificial donors (KI, H2O2, KOH) increase the voltage to -240 and -400 mW, due to improved hole transfer. The photovoltage is quenched with the addition of co-catalysts CoO[subscript x] and Co-Pi, possibly due to the removal of surface states and enhanced e/h recombination. Chapter 3 outlines a methodical exploration of the limits of water oxidation from illuminated ß-FeO(OH) suspensions. Well-defined akaganéite nanocrystals are able to produce oxygen gas from aqueous solutions in the presence of an appropriate electron acceptor. Optimal conditions were achieved by systematically varying the amount of catalyst, concentration of the electron acceptor, pH of the solution, and light intensity. A decrease in activity is shown to be the result of particle agglomeration after roughly 5 hours of illumination. A maximum O2 evolution rate of 35.2 μmol O2 h−1 is observed from an optimized system, with a QE of 0.19%, and TON of 2.58 based on total ß-FeO(OH). Chapter 4 continues to understand charge separation and transport in CdS nanorods. These nanomaterials are capable of catalytic proton reduction under visible illumination, but suffer from photo-corrosion resulting in decreased H2 production. SPS measurements show a maximum photovoltage of -230 mV at 2.75 eV and the charge separation is largely reversible. Coating the rods with graphitic carbon nitride (g-C3N4) creates a hole accepting protective layer than prevents oxidative loss of photo-activity. By adding platinum salts, additional photovoltage could be extracted through field induced charge migration from excited sub gap defect states and trap sites. The addition of a sacrificial reagent would either decrease or increase the photovoltage (depending on the reagent used) by creating additional bias in the films or charge recombination pathways. Finally, it was shown that varying the substrate has an effect on the platinum/substrate polarized charge injection. Chapter 5 Surface photovoltage is used to show for the first time the charge separation properties of Sn2TiO4, an n-type photocatalyst, a series of cuprous niobium oxides doped with tantalum (CuNb[subscript 1-y]Ta[subscript y]O[subscript x]), and a Cu (I) tantalum oxide Cu5Ta11O3.
Book Synopsis Heterostructured Photocatalysts for Solar Energy Conversion by : Srabanti Ghosh
Download or read book Heterostructured Photocatalysts for Solar Energy Conversion written by Srabanti Ghosh and published by Elsevier. This book was released on 2020-10-10 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heterostructured Photocatalysts for Solar Energy Conversion provides a comprehensive description of novel z-scheme hybrid materials based on metal oxide or chalcogenides-based semiconductor, or carbon-based nanomaterials (conducting polymers, graphene, and other carbon materials). The book explores energy conversion applications, such as hydrogen generation, water splitting, CO2 reduction or degradation of organic pollutants, and their associated new material and technology development. The book addresses a variety of topics, such as photochemical processes, materials and fabrication, degradation mechanisms, as well as challenges and strategies. The book includes in-depth discussions ranging from comprehensive understanding, to engineering of materials and applied devices. The concept of visible light active catalysis emerged in recent decades and continues to attract the scientific community. Driven primarily by an opportunity to develop novel multifunctional materials on one hand, and sustainable technologies on the other, several successful approaches have been explored. However, preparation, characterization, and application of visible light active Z-scheme heterojunction-based catalytic nanostructures are still at the foreground of research activity. Provides an overview on recently developed Z-scheme photocatalysts to stress their performance as catalysts Covers most of the important topics in photocatalysis Explores the most recent advances in synthesis to enable deeper understanding of the principles underlying electronic behavior of catalytic nanostructures, mechanistic details, and the evaluation of their effectiveness, as well as perspectives in solar light harvesting Serves as a valuable resource for better understanding of the current state of photocatalysis research and its possible applications in energy domain
Book Synopsis Surface Photovoltage Spectroscopy on Nanostructured Photocatalysts and Photovoltaic Thin-films for Solar Energy Conversion by : Benjamin Nail
Download or read book Surface Photovoltage Spectroscopy on Nanostructured Photocatalysts and Photovoltaic Thin-films for Solar Energy Conversion written by Benjamin Nail and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar energy conversion has the potential to reduce society’s dependence on fossil fuels and to diminish the harmful effects of climate change by generating clean power from the sun. The process of solar hydrogen production by photocatalytic water splitting uses solar energy to generate hydrogen fuels from water and has been explored extensively in recent years as hydrogen is considered a very promising candidate for a clean and renewable solar fuel. However, only a limited number of earth-abundant photocatalysts have been shown to be active for visible-light driven H2 evolution. New advances also continue in photovoltaic (PV) technologies such as hybrid solar cells, devices composed of inorganic semiconductor quantum dots (QDs) mixed with organic conducting polymers. This dissertation will focus on the application of Surface Photovoltage Spectroscopy (SPS) to study photochemical charge transfer processes in nanoscale photocatalysts and on the characterization of charge transfer dynamics occurring in inorganic-organic hybrid solar cell films. Chapter 2 explores a photocatalytic nickel oxide nanoparticle system modified with platinum co-catalyst for photochemical hydrogen generation. Nanocrystals of NiO have increased p-type character and improved photocatalytic activity for hydrogen evolution from water in the presence of methanol as sacrificial electron donor. Surface photovoltage spectroscopy of NiO and NiO–Pt films on Au substrates indicate a metal Pt-NiO junction with 30 mV photovoltage that promotes carrier separation. The increased photocatalytic and photoelectrochemical performance of nano-NiO is due to improved minority carrier extraction and increased p-type character, as deduced from Mott–Schottky plots, optical absorbance, and X-ray photoelectron spectroscopy data. These results are relevant to the understanding of NiO-containing photocatalysts and to the electronic properties of nanoscale metal oxides and junctions. In Chapter 3, surface photovoltage spectroscopy (SPS) was used to study the intrinsic charge transfer properties and surface states of thin films of thiol, amine, carboxylic acid supported CdSe QDs on indium tin oxide (ITO) in the absence of an external bias or electrolyte. On ITO, the QD films give positive or negative photovoltage signals (-120 to +350 mV) under sub band gap and super band gap excitation (0.1 - 0.3 mW cm−2), depending on the ligand type present at the QD surface. Experimental photovoltage values are found to correlate with the LUMO energies of the CdSe QDs, obtained from the electrochemical reduction potential in tetra-n-butylammonium hexafluorophosphate electrolyte at unadjusted pH. This suggests the possibility that the built-in potential of the ITO-QD Schottky contacts is controlled by the electronic properties of the ligands. The findings shed new light on factors controlling photochemical charge separation in films of ligand-stabilized CdSe QDs. Chapter 4 presents a study of a nanoscale doped perovskite photocatalyst, chromium-doped strontium titanate (Cr:SrTiO3). The Cr:SrTiO3 nanoparticles form as well defined cubic-shaped nanocrystals with a mean diameter of 43.5 nm (±18.8 nm) and have homogeneous composition. X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure (XANES) analysis shows that Cr:SrTiO3 particles synthesized at high temperature contain high concentrations of Cr6+ trap sites while hydrothermally synthesized particles contain only Cr3+. SPS data shows that photogenerated charge carriers from Cr3+ donor states can drive photochemical reactions (e.g methanol oxidation) at the particle surface and that those reaction rates are increased by previous light excitation of the film. SPS also shows a dependence of photovoltage magnitude on substrate work function that is explained by the built-in potential (V[subscript bi]) at the film-substrate interface. Photochemical hydrogen evolution experiments show rates of up to 85 [mu]mol/hr (1.56% AQE at 435 nm). Rates are strongly dependent on solution pH, Cr doping %, and particle synthesis method. A mild NaBH4 reduction treatment was shown to increase photocatalytic activity in Cr:SrTiO3 and decrease its Cr6+ concentration. Surface photovoltage spectroscopy (SPS) also reveals an anomalously increasing photovoltage with magnitude greater than the band gap of SrTiO3. A model is proposed to show that the unusually large photovoltage, as well as charge separation in Cr:SrTiO3 in general, can be explained by a light-activated ferroelectric effect that causes ordering of electric dipoles in the non-centrosymmetric Cr:SrTiO3 unit cells.
Book Synopsis Development of Inorganic Nanomaterials as Photocatalysts for the Water Splitting Reaction by : Fredrick Andrew Frame
Download or read book Development of Inorganic Nanomaterials as Photocatalysts for the Water Splitting Reaction written by Fredrick Andrew Frame and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The photochemical water splitting reaction is of great interest for converting solar energy into usable fuels. This dissertation focuses on the development of inorganic nanoparticle catalysts for solar energy driven conversion of water into hydrogen and oxygen. The results from these selected studies have allowed greater insight into nanoparticle chemistry and the role of nanoparticles in photochemical conversion of water in to hydrogen and oxygen. Chapter 2 shows that CdSe nanoribbons have photocatalytic activity for hydrogen production from water in the presence of Na2S/Na2SO3 as sacrificial electron donors in both UV and visible light. Quantum confinement of this material leads to an extended bandgap of 2.7 eV and enables the photocatalytic activity of this material. We report on the photocatalytic H2 evolution, and its dependence on platinum co-catalysts, the concentration of the electron donor, and the wavelength of incident radiation. Transient absorption measurements reveal decay of the excited state on multiple timescales, and an increase of lifetimes of trapped electrons due to the sacrificial electron donors. In chapter 3, we explore the catalytic activity of citrate-capped CdSe quantum dots. We show that the process is indeed catalytic for these dots in aqueous 0.1 M Na2S:Na2SO3, but not in pure water. Furthermore, optical spectroscopy was used to report electronic transitions in the dots and electron microscopy was used to obtain morphology of the catalyst. Interestingly, an increasing catalytic rate is noted for undialyzed catalyst. Dynamic light scattering experiments show an increased hydrodynamic radius in the case of undialyzed CdSe dots in donor solution. In chapter 4 we show that CdSe:MoS2 nanoparticle composites with improved catalytic activity can be assembled from CdSe and MoS2 nanoparticle building units. We report on the photocatalytic H2 evolution, quantum efficiency using LED irriadiation, and its dependence on the co-catalyst loading. Furthermore, optical spectroscopy, cyclic voltammetry, and electron microscopy were used to obtain morphology, optical properties, and electronic structure of the catalysts. In chapter 5, illumination with visible light ([lambda]> 400 nm) photoconverts a red V2O5 gel in aqueous methanol solution into a green VO2 gel. The presence of V(4+) in the green VO2 gel is supported by Electron Energy Loss Spectra. High-resolution electron micrographs, powder X-ray diffraction, and selective area electron diffraction (SAED) data show that the crystalline structure of the V2O5 gel is retained upon reduction. After attachment of colloidal Pt nanoparticles, H2 evolution proceeds catalytically on the VO2 gel. The Pt nanoparticles reduce the H2 evolution overpotential. However, the activity of the new photocatalyst remains limited by the VO2 conduction band edge just below the proton reduction potential. Chapter 6 studies the ability of IrO2 to evolve oxygen from aqueous solutions under UV irradiation. We show that visible illumination ([lambda]> 400 nm) of iridium dioxide (IrO2) nanocrystals capped in succinic acid in aqueous sodium persulfate solution leads to catalytic oxygen evolution. While the majority of catalytic hydrogen evolution comes from UV light, the process can still be driven with visible light. Morphology, optical properties, surface photovoltage measurements, and oxygen evolution rates are discussed.
Book Synopsis Preparation, Electrochemical and Photocatalytic Studies on Inorganic and Organic Nanomaterials for Solar Energy Conversion by : Rachel Lee Chamousis
Download or read book Preparation, Electrochemical and Photocatalytic Studies on Inorganic and Organic Nanomaterials for Solar Energy Conversion written by Rachel Lee Chamousis and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: New, inexpensive and non-polluting energy technologies are of great importance for civilization. A promising source is solar energy, which can be photocatalytically converted into gaseous fuel or electricity. It has been hypothesized that nanomaterials may lead to improved photoelectrochemical (PEC), suspended photocatalytic, and photovoltaic cells. This particular field of study is vast considering the various ways nanomaterials can be synthesized, manipulated, and employed. Here, several different nanomaterials are studied as photocatalysts and as components in photoelectrochemical and photovoltaic cells. The purpose is to better understand charge transfer properties and energetics of these materials, and eventually, to help find a cheap, active, and sustainable photocatalyst for our ever-increasing energy demands. Chapter 1 gives a brief introduction to the field of nanomaterials for solar energy conversion. The motivation for this research is given, water-splitting photocatalysis is explained, and the various ways nanomaterials can be employed are reviewed. Chapter 2 explains how nanomaterials such as titanium dioxide and tungsten oxide can be used to photocatalytically decompose organic contaminants in wastewater while simultaneously producing electricity. Efficiency and power output analysis of derived photoelectrochemical cells revealed the highest published values for titanium dioxide electrodes under 395 nm illumination. Chapter 3 discusses calcium niobate (TBACa2Nb3O10, TBA = tetrabutylammonium) nanosheets as a photocatalyst for hydrogen evolution from aqueous methanol solution under UV illumination. Photoelectrochemical techniques were used to study the effects of ion modification of TBACa2Nb3O10 on the energetics, specifically the position of the Fermi energy. The data shows a direct relationship between the position of the Fermi energy and the relative rate of hydrogen production. Chapter 4 explains the fabrication and function of the first fractal electrode-based organic photovoltaic cells. Although the fractal electrode enhances the interfacial area between the light absorber and electrode, enhanced charge recombination results in reduced photocurrent for fractal silver. Chapter 5 gives a selection of the photoelectrochemical properties of iridium dioxide nanoparticles and single-crystal tungsten oxide nanosheets. The data can be used to calculate the photo-onset values for each material. Chapter 6 gives supporting information on calculating the power conversion efficiency of a PEC cell.
Book Synopsis Photochemical Charge Transfer in Nanostructured Photocatalysts for Solar Hydrogen Production by : Jiarui Wang
Download or read book Photochemical Charge Transfer in Nanostructured Photocatalysts for Solar Hydrogen Production written by Jiarui Wang and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar energy is a promising sustainable energy source to reduce greenhouse gas emission from combustion of fossil fuels and slow down the global climate change. Solar hydrogen generation via photocatalytic water splitting is potentially the most cost-effective way to produce solar fuels, so the development of efficient photocatalysts is one of the most important targets for scientific research. However, the application of inorganic materials for solar water splitting is currently limited by our understanding of photochemical charge transfer on the nanoscale, where space charge layers are less effective for carrier separation. Therefore, this dissertation focuses on the preparation of well-defined photocatalysts for the water splitting reaction and on the characterization of photochemical charge transfer on their interfaces. This will be accomplished through the application of surface photovoltage and photoelectrochemical measurements, and with photocatalytic reactivity tests. Results from this study can guide the design of inorganic photocatalysts with improved efficiency for solar energy conversion into fuel. Chapter 2 describes surface photovoltage spectroscopy studies to measure the internal photovoltages in a hydrogen evolution photocatalyst, single crystalline platinum/ruthenium-modified Rh-doped SrTiO3 nanocrystals. Voltages of -0.88 V and -1.13 V are found between the light absorber and the Ru and Pt cocatalysts, respectively, and a voltage of -1.48 V for a Rh-doped SrTiO3 film on an Au substrate. The voltages shows that the Pt and Ru cocatalysts not only improve the redox kinetics but also aid charge separation in the absorber. The voltages with redox agents correlate well with the photocatalytic performance of the catalyst and are influenced by the built-in potentials of the donor-acceptor configurations, the physical separation of donors and acceptors, and the reversibility of the redox reaction. The photovoltage data also allow the identification of a photosynthetic system for hydrogen evolution (80 [mu]mol·g−11h−1) under visible light illumination (>400 nm) from 0.05 M aqueous K4[Fe(CN)6]. Chapter 3 shows that suspended p-Si nanowires obtained by etching of an Al-doped silicon wafer facilitate photochemical hydrogen evolution under visible light. The activity varies greatly between sacrificial donors and can be increased by attachment of MoS2 cocatalysts, which promote proton reduction and charge transfer at the silicon-MoS2 interface. Overall, the activity of suspended p-Si nanorods is limited by the stability of the material in neutral solutions. A basic or neutral environment with photo-excitation can lead to silicon corrosion. In 0.05 M ferrocyanide at pH 6.5, the hydrogen evolution rate for SiNW/MoS2 was as high as 106 [mu]mol (10mg)−1 h−1 accompanied by silicon corrosion. The rate without corrosion decreased to 0.64 [mu]mol (10mg)−1 h−1 at a lower pH of 4.7. With silicon corrosion, the rate also reached 117 [mu]mol (10mg)−1 h−1 in pH 6.5 0.05 M Na2SO3 solution and 678 [mu]mol (10mg)−1 h−1 in 0.1 M NaSH without pH control. Silicon corrosion was not found in formaldehyde and methanol solutions, but the rates of SiNW/MoS2 and SiNW were as low as 0.40 and 0.18 [mu]mol (10mg)−1 h−1 for methanol solution, and 0.71 and 0.27 [mu]mol (10mg)−1 h−1 for formaldehyde solution. The increased hydrogen evolution with silicon corrosion can be attributed to both electron donating of silicon and reduced charge transfer resistivity with the dissolution of surface oxide layer on silicon nanowires. These findings can improve the understanding of photochemistry of Si-MoS2 catalyst, and help avoiding silicon corrosion in photocatalysis.
Book Synopsis On Solar Hydrogen and Nanotechnology by : Lionel Vayssieres
Download or read book On Solar Hydrogen and Nanotechnology written by Lionel Vayssieres and published by John Wiley & Sons. This book was released on 2010-01-26 with total page 706 pages. Available in PDF, EPUB and Kindle. Book excerpt: More energy from the sun strikes Earth in an hour than is consumed by humans in an entire year. Efficiently harnessing solar power for sustainable generation of hydrogen requires low-cost, purpose-built, functional materials combined with inexpensive large-scale manufacturing methods. These issues are comprehensively addressed in On Solar Hydrogen & Nanotechnology – an authoritative, interdisciplinary source of fundamental and applied knowledge in all areas related to solar hydrogen. Written by leading experts, the book emphasizes state-of-the-art materials and characterization techniques as well as the impact of nanotechnology on this cutting edge field. Addresses the current status and prospects of solar hydrogen, including major achievements, performance benchmarks, technological limitations, and crucial remaining challenges Covers the latest advances in fundamental understanding and development in photocatalytic reactions, semiconductor nanostructures and heterostructures, quantum confinement effects, device fabrication, modeling, simulation, and characterization techniques as they pertain to solar generation of hydrogen Assesses and establishes the present and future role of solar hydrogen in the hydrogen economy Contains numerous graphics to illustrate concepts, techniques, and research results On Solar Hydrogen & Nanotechnology is an essential reference for materials scientists, physical and inorganic chemists, electrochemists, physicists, and engineers carrying out research on solar energy, photocatalysis, or semiconducting nanomaterials, both in academia and industry. It is also an invaluable resource for graduate students and postdoctoral researchers as well as business professionals and consultants with an interest in renewable energy.
Book Synopsis Green Photocatalysts for Energy and Environmental Process by : Saravanan Rajendran
Download or read book Green Photocatalysts for Energy and Environmental Process written by Saravanan Rajendran and published by Springer Nature. This book was released on 2019-09-04 with total page 321 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes green photocatalysts and their diverse applications in the fields of environmental sciences and energy. It especially takes a closer look at the removal of air and water pollutants, the generation of hydrogen, photo fuel cells, electrophotocatalysts, solar energy conversions, and green biophotocatalysts. Furthermore it also discusses on the role of catalysts along with their chemical reactions, challenges, past developments and directions for further research on photocatalysts. It includes recent developments of quantum dots (QDs) and photocatalytic applications of QDs such as carbon materials like carbon and graphene based QDs, metal, metal sulfide and metal oxide based QDs as well as a detailed review on various types of templates used for the preparation of porous g-C3N4 and its applications in detail. This is done with special reference to dye degradation, reduction of hexavalent Cr, and reduction of CO2 and for the evolution of H2 photocatalytically. This book offers an intriguing and useful guide for a broad readership in various fields of catalysis, material sciences, environment and energy.
Book Synopsis Chalcogenide-Based Nanomaterials as Photocatalysts by : Mohammad Mansoob Khan
Download or read book Chalcogenide-Based Nanomaterials as Photocatalysts written by Mohammad Mansoob Khan and published by Elsevier. This book was released on 2021-04-07 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chalcogenide-Based Nanomaterials as Photocatalysts deals with the different types of chalcogenide-based photocatalytic reactions, covering the fundamental concepts of photocatalytic reactions involving chalcogenides for a range of energy and environmental applications. Sections focus on nanostructure control, synthesis methods, activity enhancement strategies, environmental applications, and perspectives of chalcogenide-based nanomaterials. The book offers guidelines for designing new chalcogenide-based nanoscale photocatalysts at low cost and high efficiency for efficient utilization of solar energy in the areas of energy production and environment remediation. Provides information on the development of novel chalcogenide-based nanomaterials Outlines the fundamentals of chalcogenides-based photocatalysis Includes techniques for heterogeneous catalysis based on chalcogenide-based nanomaterials
Book Synopsis Nanostructured and Photoelectrochemical Systems for Solar Photon Conversion by : Mary D. Archer
Download or read book Nanostructured and Photoelectrochemical Systems for Solar Photon Conversion written by Mary D. Archer and published by World Scientific. This book was released on 2008 with total page 781 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book, expert authors describe advanced solar photon conversion approaches that promise highly efficient photovoltaic and photoelectrochemical cells with sophisticated architectures on the one hand, and plastic photovoltaic coatings that are inexpensive enough to be disposable on the other. Their leitmotifs include light-induced exciton generation, junction architectures that lead to efficient exciton dissociation, and charge collection by percolation through mesoscale phases. Photocatalysis is closely related to photoelectrochemistry, and the fundamentals of both disciplines are covered in this volume.
Book Synopsis Nanophotocatalysis and Environmental Applications by : Inamuddin
Download or read book Nanophotocatalysis and Environmental Applications written by Inamuddin and published by Springer. This book was released on 2019-03-29 with total page 273 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents photocatalysis as a state-of-art technology in energy production and conversion. The ever increasing demand for energy with growing economies has led to a dearth of energy sources. The exhaustive dependability on non-renewable resources of energy has not just depleted them but also lead to the birth of secondary problems such as pollution and climate change. The photoactive processes have opened a new window for the production of green energy and helped in environmental sustainability. The harnessing of renewable sources especially sun and water for fuel production and noxious gases reduction solve both the issues of pollution mitigation and energy crisis.
Book Synopsis Hybrid Molecule-nanocrystal Photon Upconversion Across the Visible and Near-infrared by : Zhiyuan Huang
Download or read book Hybrid Molecule-nanocrystal Photon Upconversion Across the Visible and Near-infrared written by Zhiyuan Huang and published by . This book was released on 2017 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: The sequential absorption of two low energy photons, followed by the emission of one higher energy photon, is known as photon upconversion. This two-photon process has potential applications in biological imaging, solar energy conversion and photocatalysis etc. Two existing strategies to realize upconversion are an inorganic system based on lanthanide doping, and an organic system based on triplet-triplet annihilation. This dissertation introduces a novel hybrid molecule-nanocrystal system that upconverts photons across visible to near-infrared. It combines the advantages of high photostability and low excitation intensity, and overcomes the limits in the previous systems. Here, the absorption of low energy photons by the semiconductor nanocrystals (NCs) is followed by the energy transfer to molecular triplet states. Triplet-triplet annihilation then occurs to create high energy singlet states that emit the upconverted light. I show the introduction of functionalized acene molecules on NC surfaces greatly enhances the upconversion quantum yields (QYs) by up to three orders of magnitidue in different systems. As one of the efficiency limiting steps in upconversion, TET is systematically studied by modifying both NC donor and molecular acceptor. TET is characterized by steady state upconversion, time-resolved transient absorption and photoluminescence spectroscopies. TET is dependent on the anchoring groups of the transmitter molecules due to different binding affinities, docking geometries, sterics, intra-molecular spin-orbit couplings and molecule-NC triplet-triplet couplings. Transmitters with phosphonic acid, carboxylic acid and imidazole as binding groups show the best upconversion performance. For the NC donors, small sizes lead to high upconversion QYs due to the large driving force. While the growth of inorganic shells passivates surface traps, TET from core-shell NCs to transmitters is dependent on the shell composition and thickness. TET is improved when submonolayer shells suppress charge transfer and decrease exciton-phonon coupling.
Book Synopsis Heterogeneous Photocatalysis by : Juan Carlos Colmenares
Download or read book Heterogeneous Photocatalysis written by Juan Carlos Colmenares and published by Springer. This book was released on 2015-12-24 with total page 419 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book explains the principles and fundamentals of photocatalysis and highlights the current developments and future potential of the green-chemistry-oriented applications of various inorganic, organic, and hybrid photocatalysts. The book consists of eleven chapters, including the principles and fundamentals of heterogeneous photocatalysis; the mechanisms and dynamics of surface photocatalysis; research on TiO2-based composites with unique nanostructures; the latest developments and advances in exploiting photocatalyst alternatives to TiO2; and photocatalytic materials for applications other than the traditional degradation of pollutants, such as carbon dioxide reduction, water oxidation, a complete spectrum of selective organic transformations and water splitting by photocatalytic reduction. In addition, heterogeneized polyoxometalate materials for photocatalytic purposes and the proper design of photocatalytic reactors and modeling of light are also discussed. This book appeals to a wide readership of the academic and industrial researchers and it can also be used in the classroom for undergraduate and graduate students focusing on heterogeneous photocatalysis, sustainable chemistry, energy conversion and storage, nanotechnology, chemical engineering, environmental protection, optoelectronics, sensors, and surface and interface science. Juan Carlos Colmenares is a Professor at the Institute of Physical Chemistry, Polish Academy of Sciences, Poland. Yi-Jun Xu is a Professor at the State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, China.
