Preface

This book presents recent advances in three major green hydrogen production pathways: photocatalysis-, electrocatalysis- and photoelectrocatalysis-based hydrogen production. The growing world economy and global population needs steady growth of energy production. Hydrogen is a promising green energy and an alternative to fossil fuels, because fossil fuels are associated with drawbacks, such as limited supply and the emission of hazardous greenhouse gases. Hydrogen gas is a clean fuel with high energy capacity (143 MJ kg⁻¹) and no toxic emissions. At present global hydrogen production is mostly derived from natural gas (48%), oil (30%) and coal (18%), with only 4% from water electrolysis. Hence, current hydrogen production largely depends on fossil fuels and it is therefore important to undertake more investigations in the field of sustainable hydrogen production through electrolysis and photocatalysis. Splitting of water to produce hydrogen and oxygen is an easy and long-standing path. H₂ production through photocatalytic, electrocatalytic and photoelectrocatalytic processes is an efficient route to address both the energy crisis and environmental problems. Catalysts play a significant role in boosting rates of reaction, provide active sites and enhance hydrogen yield in photo/electrocatalytic H₂ production. The current highly active catalysts (Pt) used are associated with various drawbacks, such as high cost, low stability, low abundance and so on. Thus, researchers are working on developing promising catalysts with high performance, cost effective and geological abundance, which will be important for a future hydrogen economy. Hence knowledge in this field needs to be shared with a greater number of researchers and industrialists to increase that 4% hydrogen production from electrolysis, to 90–100%. There are various electrocatalysts and photocatalysts that are explored for hydrogen generation, and these need to be understand. Additionally, a hybrid process of utilizing both photocatalysis and electrolysis is also being explored, involving catalysts that are active for both processes and thus termed as photoelectrochemical hydrogen production. Thus, this book focuses on describing recent research developments and possible advancements in these three scenarios.

The motivation to edit a book on this topic essentially comes from the realization that there is a need to: (1) cover photocatalysts, electrocatalysts and photoelectrocatalysts for hydrogen production; (2) comprehensively compile recent developments in the field and highlight emerging research trends that could be adopted by industry; (3) to grab the attention of industrialists, by demonstrating the research progress on these topics in a single resource; (4) to motivate both researchers and industrialists to focus on all three types of catalysts for sustainable hydrogen production; and (5) to bridge the gap between research discoveries and industrial production of hydrogen, to improve the renewable path for hydrogen production and to overcome the use of fossil fuels.

Existing books on hydrogen production provide general aspects of hydrogen production through different techniques and are thus not designed or themed to deliver information exclusively on different photo-, electro- and photoelectrocatalysts for hydrogen production, and their recent modifications in order to produce high/industrial-scale hydrogen. Our book is specifically intended to deliver recent updates in the field of photocatalysis, electrocatalysis and photoelectrocatalysis for sustainable hydrogen production, which includes: (1) photocatalysts for hydrogen production (perovskite oxides, perovskite oxynitrides, metal oxides, metal oxynitrides, metal–organic framework-based catalysts, covalent organic framework-based catalysts, transition metal dichalcogenides, metal phosphides, carbon-based catalysts and so on); (2) electrocatalysts for hydrogen production; and (3) catalysts for photoelectrochemical hydrogen production, which have not been discussed in previous books. This book includes contributions from international authors who are key researchers in the field of hydrogen production through photocatalysis and electrocatalysis. We have planned this book keeping in mind international researchers, industrialists, academics and scientists working in the field of hydrogen production to solve the problems of energy demand. We hope this book helps in progress towards green hydrogen production research and commercial advancements.

R. Geetha Balakrishna

R. Shwetharani

Theerthagiri Jayaraman