Photoelectrochemical water splitting has been identified as a suitable and sustainable approach to address two of the main issues facing humanity: environmental protection, and clean and sustainable energy production. Nanostructure-based photoelectrochemical water splitting is a highly promising process for converting solar energy into hydrogen energy. This reference text presents the latest research and developments in the area of photoactive nanostructured materials and their photoelectrochemical water splitting for applications in environmental protection, clean energy production and chemical amalgamation/processing.

Nanostructured materials for visible light driven photo-processes such as photodegradation of organic pollutants and photoelectrochemical (PEC) water oxidation for hydrogen production are very attractive because of the positive impact on the environment. Metal oxides-based nanostructures are widely used in these photoprocesses due to their unique properties. But single nanostructured metal oxide material might suffer from low efficiency and instability in aqueous solutions under visible light. These facts make it important to have an efficient and reliable nanocomposite for the photo-processes. The combination of different nanomaterials to form a composite configuration can produce a material with new properties. The new properties which are due to the synergetic effect, are a combination of the properties of all the counterparts of the nanocomposite. Zinc oxides (ZnO) have unique optical and electrical properties which grant it to be used in optoelectronics, sensors, solar cells, nanogenerators, and photocatalysis activities. Although ZnO absorbs visible light from the sun due to the deep level band, it mainly absorbs ultraviolet wavelengths which constitute a small portion of the whole solar spectrum range. Also, ZnO has a problem with the high recombination rate of the photogenerated electrons. These problems might reduce its applicability to the photo-process. Therefore, our aim is to develop and investigate different nanocomposites materials based on the ZnO nanostructures for the enhancement of photocatalysis processes using the visible solar light as a green source of energy. Two photo-processes were applied to examine the developed nanocomposites through photocatalysis: (1) the photodegradation of organic dyes, (2) PEC water splitting. In the first photo-process, we used the ZnO nanoparticles (NPs), Magnesium (Mg)-doped ZnO NPs, and plasmonic ZnO/graphene-based nanocomposite for the decomposition of some organic dyes that have been used in industries. For the second photo-process, ZnO photoelectrode composite with different silver-based semiconductors to enhance the performance of the ZnO photoelectrode was used for PEC reaction analysis to perform water splitting. The characterization and photocatalysis experiment results showed remarkable enhancement in the photocatalysis efficiency of the synthesized nanocomposites. The observed improved properties of the ZnO are due to the synergetic effects are caused by the addition of the other nanomaterials. Hence, the present thesis attends to the synthesis and characterization of some nanostructured materials composite with ZnO that are promising candidates for visible light-driven photo-processes.

The occurrence of available energy reservoirs is decreasing steeply, therefore we are looking for an alternative and sustainable renewable energy resources. Among them, hydrogen is considered as green fuel with a high density of energy. In nature, hydrogen is not found in a free state and it is most likely present in the compound form for example H2O. Water covers almost 75% of the earth planet. To produce hydrogen from water, it requires an efficient catalyst. For this purpose, noble materials such as Pt, Ir, and Ru are efficient materials for water splitting. These precious catalysts are rare in nature, very costly, and are restricted from largescale applications. Therefore, search for a new earth-abundant and nonprecious materials is a hot spot area in the research today. Among the materials, nanomaterials are excellent candidates because of their potential properties for extended applications, particularly in energy systems. The fabrication of nanostructured materials with high specific surface area, fast charge transport, rich catalytic sites, and huge ion transport is the key challenge for turning nonprecious materials into precious catalytic materials. In this thesis, we have investigated nonprecious nanostructured materials and they are found to be efficient for electrochemical water splitting. These nanostructured materials include MoS2-TiO2, MoS2, TiO2, MoSx@NiO, NiO, nickeliron layered double hydroxide (NiFeLDH)/Co3O4, NiFeLDH, Co3O4, Cu-doped MoS2, Co3O4- CuO, CuO, etc. The composition, morphology, crystalline structure, and phase purities are investigated by a wide range of analytical instruments such as XPS, SEM, HRTEM, and XRD. The production of hydrogen/oxygen from water is obtained either in the acidic or alkaline media. Based on the functional characterization we believe that these newly produced nanostructured materials can be capitalized for the development of water splitting, batteries, and other energy-related devices.

This book describes the role and fundamental aspects of the diverse ranges of nanostructured materials for energy applications in a comprehensive manner. Advanced nanomaterial is an important and interdisciplinary field which includes science and technology. This work thus gives the reader an in depth analysis focussed on particular nanomaterials and systems applicable for technologies such as clean fuel, hydrogen generation, absorption and storage, supercapacitors, battery applications and more. Furthermore, it not only aims to exploit certain nanomaterials for technology transfer, but also exploits a wide knowledge on avenues such as biomass-derived nanomaterials, carbon dioxide conversions into renewable fuel chemicals using nanomaterials. These are the areas with lacunae that demand more research and application.

This book focuses on the electrochemical and nanostructural properties of new photoanode/electrolyte combinations used in the development of novel surface-modified nanomaterials for environmental applications. As water treatment is rapidly becoming a global challenge due to the increasing complexity and number of the various pollutants present, the book explores fundamental issues relating to environmental applications of nanomaterials. It addresses relevant topics ranging from electrochemical synthesis and characterization, to applications of photoanodes in corrosion prevention and biosensors for wastewater treatment. Featuring up-to-date experimental results on nanomaterials for detection of pharmaceuticals and heavy metals in wastewater, this contributed volume is useful to electrochemical researchers, materials scientists, and chemical and civil engineers interested in advanced photoelectrochemical research for environmental applications.

This book describes the hydrogen fuel generation from water via photoelectrochemical process. It elaborates the theory and fundamental concepts of photoelectrochemistry to understand the photoelectrochemical process for water splitting to generate hydrogen fuel. The book further deliberates about the hydrogen as a futuristic chemical fuel to store solar energy in the form of chemical bonds and also as a renewable alternative to fossil fuels. The book establishes the need for hydrogen fuel and discusses the standards and practices used for solar driven photoelectrochemical water splitting. It also discusses the current and future status of the nanomaterials as efficient photoelectrodes for solar photoelectrochemical water splitting. The book will be of interest to the researchers, students, faculty, scientists, engineers, and technologists working in the domain of material science, energy harvesting, energy conversion, photo electrochemistry, nanomaterials for photo-electrochemical (PEC) cell, etc.

This issue features fourteen peer-reviewed papers originating from The 6th International Symposium on Nanostructured Materials and Nanotechnology. It includes Nanostructured coatings by cluster beam deposition; a new greener synthetic route to cadmium/lead selenide and telluride nanoparticles; and much more. Held in January 2012, during the 36th International Conference on Advanced Ceramics and Composites (ICACC), the symposium covered a broad range of issues, including synthesis, processing, modeling, and structure-property correlations in nanomaterials and nanocomposites, enabling scientists, engineers, and technologists from around the world to explore the latest developments in the field.

Hydrogen gas obtained by electrochemical and photoelectrochemical water splitting has long been proposed as a clean and sustainable alternative to hydrocarbon fuels. While noble metals such as Pt and Ir, are capable of splitting water at low overpotentials, the widespread implementation of inexpensive solar-driven water-splitting systems and electrolyzers requires, among other things, the development of robust, efficient, and abundant alternatives to noble metal catalysts. Recently, transition metal phosphides (MxPy) have been recognized as a promising class of Earth-abundant electrocatalysts for the hydrogen evolution reaction (HER), capable of operating with low overpotentials at benchmark current densities while sustaining high stabilities even in harsh conditions. This dissertation describes the progress that has been made in this field and aims to provide helpful insights into the synthesis, characterization and electrochemical testing of transition metal phosphides, and electrocatalysts in general. In particular, it highlights our work on the identification of iron phosphide (FeP), in the form of monodisperse and hollow colloidal nanocrystals, as a highly active HER catalysts in acidic and neutral aqueous solutions. It also discusses the development of more scalable approaches to the preparation of these materials directly onto the surface of current collectors and photoelectrodes, while maintaining high electrocatalytic activities for both the hydrogen and oxygen evolution reactions. Finally, we present new synthetic approaches to higher-order colloidal hybrid nanoparticles based on supersaturation-precipitation strategies, which could open the door to nanostructures of relevance to photocatalytic fuels production.

Nanostructured Materials for Visible Light Photocatalysis describes the various methods of synthesizing different classes of nanostructured materials that are used as photocatalysts for the degradation of organic hazardous dyes under visible light irradiation. The first three chapters include a general introduction, basic principles, mechanisms, and synthesis methods of nanomaterials for visible light photocatalysis. Recent advances in carbon, bismuth series, transition metal oxide and chalcogenides-based nanostructured materials for visible light photocatalysis are discussed. Later chapters describe the role of phosphides, nitrides, and rare earth-based nanostructured-based materials in visible light photocatalysis, as well as the characteristics, synthesis, and fabrication of photocatalysts. The role of doping, composites, defects, different facets, morphology of nanostructured materials and green technology for efficient dye removal under visible-light irradiation are also explored. Other topics covered include large-scale production of nanostructured materials, the challenges in present photocatalytic research, the future scope of nanostructured materials regarding environmental hazard remediation under visible light, and solar light harvesting. This book is a valuable reference to researchers and enables them to learn more about designing advanced nanostructured materials for wastewater treatment and visible-light irradiation. Covers all the recent developments of nanostructured photocatalytic materials Provides a clear overview of the mechanism of visible light photocatalysis and the controlled synthesis of nanostructured materials Assesses the major challenges of creating visible light photocatalysis systems at the nanoscale

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.