Water splitting theory

Abstract

Fossil fuels currently provide about 80% of the world's energy, highlighting the need to transition to clean and sustainable sources due to environmental issues and global warming. Solar energy offers a promising avenue for hydrogen production through water splitting, which acts as a clean energy carrier. To efficiently utilize solar energy, eco-friendly methods for conversion, storage, and distribution are essential, with water photoelectrolysis emerging as a key technology utilizing semiconductor materials. These semiconductors enable hydrogen and oxygen evolution reactions, focusing on improving the kinetics of the more challenging oxygen evolution reaction (OER) to boost overall efficiency. This chapter reviews fundamental concepts of solar water splitting, emphasizing thermodynamics, materials, and types of water-splitting systems. It highlights the importance of optimizing thermodynamic parameters and material properties to enhance the performance of photocatalytic, photoelectrochemical, and photovoltaic techniques for water splitting. Through this exploration, the chapter aims to address advances and challenges in harnessing solar energy for sustainable hydrogen production. © 2025 Elsevier Inc. All rights reserved.