Electrocatalytic, photocatalytic, and photoelectrochemical hydrogen generation

This chapter provides a comprehensive overview of the critical issues surrounding energy and the environment in the context of sustainable development. It underscores the urgency of reducing reliance on fossil fuels due to environmental concerns and identifies hydrogen as a promising clean energy source. The historical development of hydrogen production methods, including fossil fuel-based and water electrolysis, is traced, with an emphasis on the challenges and advancements in technology. Notably, hydrogen generation with a detailed history and mechanism was adopted in electrocatalytic (EC), photocatalytic (PC), and photoelectrochemical (PEC) approaches. Specifically, for EC reaction, the Volmer-Tafel and Volmer-Heyrovsky mechanisms were discussed under various media. For PC catalysts, type-I, type-II, type-III, Z-type, and S-scheme heterojunctions were introduced. The advantage and charge transfer pathway were discussed for each type of heterojunction. By combining the advantages of PC and EC methods, the PEC device with various configurations was presented and discussed. Overall, the chapter concludes by outlining the principles of hydrogen production from water decomposition using EC, PC, and PEC catalysts, emphasizing the significance of fundamental research for catalytic efficiency improvement. The ultimate goal is to contribute to global carbon capping and carbon neutrality, providing direction for the field of hydrogen evolution.