Highly active, low cost and durable electrocatalysts are desired for the development and commercialization of fuel cells and metal-air batteries. The efficiency of these devices is significantly limited by the activation of oxygen-involved reactions, namely oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Precious metals (such as Pt) and metal oxides (such as RuO2) are traditional electrocatalysts for ORR and OER, respectively. However, the electrocatalytic performance of these precious metal-based nanomaterials is still hindered by their scarcity, high cost, insufficient activity and poor durability. Recently, developing cost-efficient and highly active electrocatalysts to replace the precious metals and oxides have obtained increasing attentions. To enhance the performance of ORR electrocatalysis, formation of PtM (M=Fe, Co, Ni, Cu) is one of most widely used strategies. The utilization of PtM can not only decrease the overall cost but improve the catalytic activity due to the synergistic effect between Pt and M. In addition, porous carbon-based nanomaterials, such as heteroatom-doped carbon, metal-nitrogen-carbon (M-N-C) nanostructures and carbon/nonprecious metal hybrids, have also been demonstrated to be promising candidates for ORR catalysis in alkaline media. These porous catalysts can effectively reduce the cost because of the absence of precious metals. Besides, the unique porous structures are favorable for mass transport and electron transfer, thus improving ORR catalytic performance. For OER electrocatalysis, a multitude of efforts have been devoted to investigate earth-abundant and highly active catalysts, such as transition metal-based nanomaterials (alloys, oxides, phosphides, phosphates, hydroxides, etc.). The corresponding OER catalytic performance can be effectively improved by tailoring the intrinsic nature of the catalysts as well as forming sufficient active sites, which can be achieved by tuning the elemental composition and increasing the surface area. Herein, a large variety of nanostructured electrocatalysts with different composition and morphology were designed and synthesized. Thanks to their compositional and morphological advances, these catalysts have been demonstrated to be active for ORR or OER.

Metal Oxide-Based Nanostructured Electrocatalysts for Fuel Cells, Electrolyzers, and Metal-Air Batteries is a comprehensive book summarizing the recent overview of these new materials developed to date. The book is motivated by research that focuses on the reduction of noble metal content in catalysts to reduce the cost associated to the entire system. Metal oxides gained significant interest in heterogeneous catalysis for basic research and industrial deployment. Metal Oxide-Based Nanostructured Electrocatalysts for Fuel Cells, Electrolyzers, and Metal-Air Batteries puts these opportunities and challenges into a broad context, discusses the recent researches and technological advances, and finally provides several pathways and guidelines that could inspire the development of ground-breaking electrochemical devices for energy production or storage. Its primary focus is how materials development is an important approach to produce electricity for key applications such as automotive and industrial. The book is appropriate for those working in academia and R&D in the disciplines of materials science, chemistry, electrochemistry, and engineering. Includes key aspects of materials design to improve the performance of electrode materials for energy conversion and storage device applications Reviews emerging metal oxide materials for hydrogen production, hydrogen oxidation, oxygen reduction and oxygen evolution Discusses metal oxide electrocatalysts for water-splitting, metal-air batteries, electrolyzer, and fuel cell applications

Hydrogen gas obtained though the electrolysis of water has long been proposed as a clean and sustainable alternative to fossil fuels. The widespread implementation of electrolyzers and solar-driven water-splitting systems is underpinned by the development of the individual components that comprise these systems, which must be efficient, robust and scalable. Among these components, highly active electrocatalysts are required to carry out the water-splitting half-reactions, the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Electrocatalysts based on noble metals such as Pt and Ir, are capable of carrying out the HER and OER at low overpotentials, however their high cost and scarcity has motivated the discovery and development of robust, efficient, and Earth-abundant alternatives. Transition metal phosphides have recently been identified as a promising family of Earth-abundant electrocatalysts for the HER, and are capable of operating with low overpotentials at operationally relevant current densities while exhibiting stability under strongly acidic conditions. In this dissertation, I highlight the progress that has been made in this field and provide insights into the synthesis, characterization and electrochemical behavior of transition metal phosphides as HER electrocatalysts. I describe that iron phosphide (FeP), synthesized as nanoparticles having a uniform, hollow morphology, exhibits among the highest HER activities reported to date in both acidic and neutral-pH aqueous solutions. Additionally, under UV illumination in both acidic and neutral-pH solutions, FeP nanoparticles supported on TiO2 are able to sustain photcatalytic H2 production over several hours. I also discuss the synthesis, characterization and electrochemical performance of cobalt phosphide (Co2P) nanoparticles having a hollow, multifaceted, crystalline morphology as another highly active Earth-abundant HER catalyst material. Importantly, the Co2P nanoparticles are morphologically equivalent to previously reported CoP nanoparticle HER catalysts, allowing a direct side-by-side evaluation of their HER activities. Such comparisons of different metal phosphide HER catalysts with the same constituent elements and morphologies are important for identifying the key materials characteristics that lead to high activity.Unlike the various metal phosphide catalysts available for the HER, OER electrocatalysts that facilitate sustained oxygen production at device-relevant current densities in strongly acidic electrolytes have been limited almost exclusively to precious metal oxides. I demonstrate that nanostructured films of cobalt oxide (Co3O4) on fluorine-doped tin oxide (FTO) substrates, function as active electrocatalysts for the OER in highly acidic conditions. The Co3O4/FTO electrodes evolve oxygen with near-quantitative Faradaic yields and maintain operationally relevant current densities for over 12 h at a moderate overpotentials, making it one of the few Earth-abundant electrocatalytic systems capable of sustained oxygen evolution in acidic conditions.

This book focuses on nanotechnology in electrocatalysis for energy applications. In particular the book covers nanostructured electrocatalysts for low temperature fuel cells, low temperature electrolyzers and electrochemical valorization. The function of this book is to provide an introduction to basic principles of electrocatalysis, together with a review of the main classes of materials and electrode architectures. This book will illustrate the basic ideas behind material design and provide an introductory sketch of current research focuses. The easy-to-follow three part book focuses on major formulas, concepts and philosophies. This book is ideal for professionals and researchers interested in the field of electrochemistry, renewable energy and electrocatalysis.

Abstract: Water Electrolysis is one of the most promising techniques to generate H2 gas, which is an alternative clean source of energy. Hydrogen provides almost three times the energy provided by gasoline, helping to solve the global warming problem caused by the currently used fossil fuels. As any electrochemical reaction is composed of two half reactions, a setup of working and counter electrodes is used to study the catalytic activity towards the targeted reaction, where each electrode carries one of the two-half reactions. In this dissertation, the stability of a number of the commonly used counter electrodes was examined to identify a stable counter electrode to avoid the deceptive enhancement caused by the dissolution and redeposition of the counter electrode on the working electrode during operation. Commercial titanium mesh has been introduced as an alternative emerging low-dissolution counter electrode, which was proven to be very stable and convenient to study the HER in acidic media. The second part of the dissertation focused on the working electrode, where various nanostructures were explored as catalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). First, boron carbon nitride (BCN) nanosheets were studied as an electrocatalyst for HER. BCN comprises the unique physicochemical properties of both graphene and 2D hexagonal boron nitride, including the electrical conductivity, mechanical, and chemical stability. Besides, the heteropolar bonding between N and B can improve its electroactivity. An innovative technique was introduced to fabricate 2D BCN hetero-structure nanosheets with various Cu:BCN weight ratios. The fabricated composites showed unique electrocatalytic properties for HER. Specifically, the overpotential of the 0.125 Cu-BCN composite at a current density of -10 mA/cm2 vs RHE is 50% lower than that of pristine BCN. Moreover, C76 was investigated as a 0D catalyst, which showed tremendous enhancement in the catalytic HER activity due to the synergistic effect between C76 and nickel foam substrate. The C76/Ni showed almost the same activity as the benchmark Pt/C catalyst. Finally, NiCoMnFe-phosphide nanosheets deposited on commercial Ti mesh were investigated as a ternary electrocatalyst for both HER and OER. The electrochemical measurements showed the NiCoMnFe-P composite to have the lowest overpotential towards HER (-200 mV) at -10 mAcm-2, lowering the overpotential needed to drive the reaction by almost 40% for HER compared to that of blank Ti mesh. For overall water splitting, a cell voltage of 1.71 V was recorded at a current density of 10 mAcm-2.

Nanomaterials have recently garnered significant attention and practical importance for heterogeneous electrocatalysis. This book presents recent developments in the design, synthesis, and characterisation of nanostructured electrocatalytic materials, with a focus on applications to energy and wastewater treatment. Electrocatalytic nanomaterials can enhance process efficiency and sustainability, thus providing innovative solutions for a wide array of areas such as sustainable energy production, conversion, and wastewater treatment. Readers will gain insights into the latest breakthroughs in electrocatalysis and the activity of nanomaterials in energy conversion applications, e.g., fuel cells, hydrogen production, water splitting, and electro/photocatalytic water splitting, as well as for wastewater treatment. The book explores the development of advanced electrocatalysts, particularly hybrid materials.

The Advances in Inorganic Chemistry series, presents timely and informative summaries on current progress in a variety of subject areas. This acclaimed serial features reviews written by experts in the field, serving as an indispensable reference to advanced researchers that empowers readers to pursue new developments in each field. Users will find this to be a comprehensive overview of recent findings and trends from the last decade that covers various kinds of inorganic topics, from theoretical oriented supramolecular chemistry, to the quest for accurate calculations of spin states in transition metals. Provides the authority and expertise of leading contributors from an international board of authors Presents the latest release in the Advances in Inorganic Chemistry series Includes the latest information on nanoscale coordination chemistry