Photocatalytic Hydrogen Generation Enabled by Nanostructured TiO₂ Materials

As the world energy crisis and pollution problems increase, it is imperative to take advantage of clean and renewable energy. Being recognized as one of the most promising clean energy sources, solar energy has garnered much attention. Meanwhile, hydrogen (H₂) represents a potentially high-efficiency and environmentally- friendly clean fuel for energy applications. In recent years, there has been a considerable increase in utilizing sunlight for H₂ production via photocatalytic water splitting because H₂ can be sustainably generated from water. As an advanced physicochemical photocatalytic process, semiconductor photocatalysis has been employed for photocatalytic H₂ evolution. Among various oxide semiconductor photocatalysts, TiO₂ has received much attention due to its outstanding properties including chemical stability, strong oxidizing activity, corrosion resistance and nontoxicity. This chapter aims to introduce the key mechanisms for water splitting to generate H₂, two different types of water splitting techniques, and key experimental parameters (including sacrificial agent, pH of solution, reaction temperature and irradiation light intensity) that influence H₂ generation are discussed. Recent developments in pristine TiO₂ nanostructures and modified TiO₂ nanostructures are also highlighted. A review of current challenges and the future outlook for research in this area are provided. We aim to give comprehensive background information and contribute a guide for future research.