A review of TiO2 nanostructured materials for hydrogen generation through photocatalytic and photoelectrochemical water splitting

In this comprehensive review, recent advances in water-splitting applications using TiO₂ as a photocatalyst are explored, with a focus on the fundamental principles of TiO₂ nanostructures and an overview of photocatalytic (PC) and photoelectrochemical (PEC) water splitting. The basic mechanism of water splitting is discussed in detail, covering the requirement for the photocatalysts, interfacial charge transport, and process quantification. The history, properties, and characterization techniques of TiO₂ photocatalysts are thoroughly reviewed, along with fabrication methods such as anodization, hydrothermal synthesis, sol-gel processes, and template-assisted methods, as well as modification strategies like doping, heterojunctions, and other treatments. Finally, a comparison of PC and PEC water-splitting processes is provided, highlighting system differences, their advantages, limitations, and recent advancements to offer readers a comprehensive understanding of hydrogen generation using TiO₂ nanostructures and to inspire innovative strategies for hydrogen production.