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| Author | : Alexey S. Cherevan |
| Publisher | : |
| Total Pages | : 217 |
| Release | : 2014 |
| Genre | : |
| ISBN | : |
| Author | : Dominik Eder |
| Publisher | : Walter de Gruyter GmbH & Co KG |
| Total Pages | : 556 |
| Release | : 2014-08-20 |
| Genre | : Technology & Engineering |
| ISBN | : 3110269864 |
Nanocarbon-Inorganic Hybrids is dedicated exclusively to the new family of functional materials, covering a multidisciplinary research field that combines materials science, chemistry and physics with nanotechnology and applied energy science. It provides a concise introduction into fundamental principles of nanocarbons, defines hybrids and composites, explains the physics behind sustainability, and illustrates requirements for successful implementation in energy applications. It further reviews the current research on developing concepts for designing nanocarbon hybrids, unravels mechanistic details of interfacial electron transfer processes and highlights future challenges and perspectives associated with exploiting these exciting new materials in commercial energy applications and beyond. This comprehensively written book is indispensable for Master and PhD students seeking to become familiar with a modern fi eld of knowledge-driven material science as well as for senior researchers and industrial staff scientists who explore the frontiers of knowledge.
| Author | : Zhiqun Lin |
| Publisher | : Woodhead Publishing |
| Total Pages | : 346 |
| Release | : 2018-03-19 |
| Genre | : Technology & Engineering |
| ISBN | : 0081019785 |
Multifunctional Photocatalytic Materials for Energy discusses recent developments in multifunctional photocatalytic materials, such as semiconductors, quantum dots, carbon nanotubes and graphene, with an emphasis on their novel properties and synthesis strategies and discussions of their fundamental principles and applicational achievements in energy fields, for example, hydrogen generation from water splitting, CO2 reduction to hydrocarbon fuels, degradation of organic pollutions and solar cells. This book serves as a valuable reference book for researchers, but is also an instructive text for undergraduate and postgraduate students who want to learn about multifunctional photocatalytic materials to stimulate their interests in designing and creating advanced materials. Covers all aspects of recent developments in multifunctional photocatalytic materials Provides fundamental understanding of the structure, properties and energy applications of these materials Contains contributions from leading international experts in the field working in multidisciplinary subject areas Focuses on advanced applications and future research advancements, such as graphene-based nanomaterials and multi-hybrid nanocomposites Presents a valuable reference for researchers and students that stimulates interest in designing advanced materials for renewable energy resources
| Author | : Fredrick Andrew Frame |
| Publisher | : |
| Total Pages | : |
| Release | : 2010 |
| Genre | : |
| ISBN | : 9781124508597 |
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.
| Author | : Troy K. Townsend |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 80 |
| Release | : 2014-03-19 |
| Genre | : Science |
| ISBN | : 331905242X |
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.
| Author | : Neelu Chouhan |
| Publisher | : CRC Press |
| Total Pages | : 310 |
| Release | : 2017-01-27 |
| Genre | : Science |
| ISBN | : 1315279630 |
Cleavage of water to its constituents (i.e., hydrogen and oxygen) for production of hydrogen energy at an industrial scale is one of the "holy grails" of materials science. That can be done by utilizing the renewable energy resource i.e. sunlight and photocatalytic material. The sunlight and water are abundant and free of cost available at this planet. But the development of a stable, efficient and cost-effective photocatalytic material to split water is still a great challenge. To develop the effective materials for photocatalytic water splitting, various type of materials with different sizes and structures from nano to giant have been explored that includes metal oxides, metal chalcogenides, carbides, nitrides, phosphides, and so on. Fundamental concepts and state of art materials for the water splitting are also discussed to understand the phenomenon/mechanism behind the photoelectrochemical water splitting. This book gives a comprehensive overview and description of the manufacturing of photocatalytic materials and devices for water splitting by controlling the chemical composition, particle size, morphology, orientation and aspect ratios of the materials. The real technological breakthroughs in the development of the photoactive materials with considerable efficiency, are well conversed to bring out the practical aspects of the technique and its commercialization.
| Author | : Antonella Profumo |
| Publisher | : Mdpi AG |
| Total Pages | : 106 |
| Release | : 2021-10-26 |
| Genre | : Science |
| ISBN | : 9783036517483 |
This book gathers selected research on the preparation, characterization and application of new organic/inorganic composites endowed with photo(electro)catalytic properties for the photocatalytic production of H2. In these pilot studies, the photoactive materials were tested under either UV-visible or, even more conveniently, under visible light for H2 evolution in "sacrificial water splitting" or "photoreforming" systems. In addition, a review article on the use of 2D materials and composites as potential photocatalysts for water splitting is included.
| Author | : Anish Khan |
| Publisher | : Woodhead Publishing |
| Total Pages | : 872 |
| Release | : 2018-11-30 |
| Genre | : Technology & Engineering |
| ISBN | : 0081025106 |
Nanocarbon and Its Composites: Preparation, Properties and Applications provides a detailed and comprehensive review of all major innovations in the field of nanocarbons and their composites, including preparation, properties and applications. Coverage is broad and quite extensive, encouraging future research in carbon-based materials, which are in high demand due to the need to develop more sustainable, recyclable and eco-friendly methods for materials. Chapters are written by eminent scholars and leading experts from around the globe who discuss the properties and applications of carbon-based materials, such as nanotubes (buckytubes), fullerenes, cones, horns, rods, foams, nanodiamonds and carbon black, and much more. Chapters provide cutting-edge, up-to-date research findings on the use of carbon-based materials in different application fields and illustrate how to achieve significant enhancements in physical, chemical, mechanical and thermal properties. Demonstrates systematic approaches and investigations from design, synthesis, characterization and applications of nanocarbon based composites Aims to compile information on the various aspects of synthesis, properties and applications of nano-carbon based materials Presents a useful reference and technical guide for university academics and postgraduate students (Masters and Ph.D.)
| Author | : Jing Zhao |
| Publisher | : |
| Total Pages | : |
| Release | : 2014 |
| Genre | : |
| ISBN | : 9781321610314 |
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.
| Author | : Naser D. Alenzi |
| Publisher | : |
| Total Pages | : |
| Release | : 2012 |
| Genre | : |
| ISBN | : |
Hydrogen production by water-splitting using solar energy and nanostructure photocatalysts is very promising as a renewable, efficient, environmentally clean technology. The key is to reduce the cost of hydrogen production as well as increase the solar-to-hydrogen conversion efficiency by searching for cost-effective photocatalytic materials. In this dissertation, energy efficiency calculation was carried out based on hydrogen production observation to evaluate the nanomaterials activity. The results are important to gain better understanding of water-splitting reaction mechanism. Design, synthesis, characterization/properties and application of these nanomaterials was the road-map to achieve the research objectives. The design of TiO2 is selected based on unique photocatalytic and photovoltaic properties and high stability in aqueous solution. Various structures of nanocomposites TiO2 were designed according to their characteristics and potential activity. TiO2 with quantum dots, nanocomposites thin film, nanofibers, nanorods, nanowires (core/shell), nanotubes, nanopowders, nanoparticles, and nanosphere decorated with low cost metals, sensitized with dye, and doped with nitrogen are designed. Green physical and chemical synthesis methods such as sol-gel techniques, autoclave, microwave, electrospinning, wet impregnation, hydrothermal, chemical vapor deposition, template-based fabrication (porous anodic aluminium oxide membrane), drop casting, dip coating, wet coating were used to synthesize and fabricate the nanomaterials and quantum dots. Both bottom-up and top-down synthesis techniques were used. The ability to control and manipulate the size, shape/geometry, crystal structure, chemical compositions, interaction and interface properties of these materials at nano-scale during the synthesis enable to enhance their thermal, optical, chemical, electrical ... etc. properties. Several characterization techniques such as XRD, XPS, EDS, SEM, UV-visible spectra, and optical microscopic and digital camera were also obtained to characterize the properties and confirm to achieve the desired design. The application or processing to test the activity of these nanomaterials for hydrogen production by water-splitting was conducted through extensive experimental program. It was carried out in a one photo-single column experimental set-up to detect hydrogen evolution. A high throughput screening process to evaluate single photo reduction catalysts was established here for simplicity, safety, cost-effective and flexibility of testing nanomaterials for water photoreduction reactivity and hydrogen generation. Therefore, methanol as electron donor or oxidation agent was mixed with water in equal volume ratio in order to prevent the oxygen evolution and only measured the time course of hydrogen production. The primary objectives of this study is to investigate the following (1) The structure-properties relationship through testing quantum dots, nanocomposites thin film, nanofibers, nanorods, nanowires (core/shell), nanotubes, nanopowders, nanoparticles, nanospheres of TiO2 decorated with metals, dye sensitization, and nitrogen-doping. (2) The role of adding electron donors/relays to solution and their effect on semiconductor surface-electrolyte interface under constant conditions such as KI, Mv+2, NaCl, NaHCO3, sea and pure water. (3) Band gap and defect engineering by cation and anion doping. (4) Quantum dots and dye sensitization effect. The nanomaterials activity evaluated based on observed hydrogen production rate (umol/h/g) experimentally and based on the energy efficiency (percent) calculation. Major findings in this dissertation are (1) A high throughput screening process to evaluate single photoreduction catalysts for solar-hydrogen production by water-splitting was established. (2) nanofibers structure of TiO2 doped with nitrogen, sensitized with dye (Rose Bengal Sodium) and quantum dots (CuInS2), and decorated with metals (Ag) showed the high solar-to-hydrogen conversion efficiency and high hydrogen production rate (3) Simple, safe, inexpensive, robust, efficient and green physical and chemical synthesis methods were used to prepare the nanomaterials and quantum dots. (4) Gaining insight and better understanding of water-splitting reaction mechanism by (a) Studying the structure-properties relationship of nanomaterials (b) Studying the role of additives on surface-interface chemistry of semiconductor and electrolyte (c) Knowing how to reduce the electron-hole recombination reactions to enhance quantum efficiency (d) Extending the absorption of nanomaterials to harness the visible light of solar spectrum radiation by doping and defect chemistry.
