Major Trends and Mechanistic Insights for the Development of TiO₂-Based Nanocomposites for Visible-Light-Driven Photocatalytic Hydrogen Production

Hydrogen production via visible-light-driven photocatalytic processes based on the permanentely available sunlight energy is considered as one of the most efficient strategies for solving energy issues facing human society and environmental crisis. TiO₂-based phototcatalysts have been reported to be the most common and efficient photocatalysts, especially for water splitting; it is promoted as a suitable candidate because of its low cost, high stability, and being eco-friendly semiconductor. Although, TiO₂ photocatalysts have some drawbacks such as their wide bandgap, their high overpotential for the evolution of hydrogen, and their rapid electron–hole pair recombination rates, which impede its practical application. Therefore, numerous approaches are addressed for developing a variety of nanocomposites photocatalysts to be used in visible-light photocatalytic hydrogen production to overcome these shortcomings; these approaches can be categorized into four main strategies: doping, dye sensitization, semiconductor coupling, and coupling with carbon-based materials. These major trends displayed significant achievements in the design and construction of efficient visible-light-driven TiO₂-based photocatalysts by enhancing their sunlight absorption capability, the charge-carriers separation, and the corrosion resistance of the photocatalysts. In this chapter, the major trends and the corresponding mechanistic insights will be summarized with examples on the recent studies of visible-light-driven nanocomposites photocatalysts employed in photocatlytic hydrogen production.