Prospects, challenges, and opportunities of the metals-modified TiO2 based photocatalysts for hydrogen generation under solar light irradiation: A review

Hydrogen (H2) is the most promising energy carrier as an alternative to diminishing fossil fuels because it is a safe, renewable, green energy resource and is environmentally sustainable. TiO2 has received a lot of interest among photocatalytic materials because of its exceptional physicochemical features and strong catalytic performance in catalysis systems. In this review, we aim to provide an overview of the basic principle for photocatalytic water splitting, recent developments, comprehensive insights into the metal-modified TiO2 interface to improve the H2 production efficiency, doping materials, photocatalytic mechanism, and merits of metal-modified TiO2 photocatalyst. The processes in TiO2 photocatalysis are summarized based on the recent progress made in the fundamental instigations of bond breaking/forming and possible energy transfer processes in TiO2 photocatalysis on the TiO2 model surfaces, both experimentally and theoretically. The basic principles that govern TiO2 photocatalysis and the mechanistic studies focusing on photocatalytic reactions have been discussed. This review would provide new inspirations and strategies to bring innovations in metal-modified photocatalytic materials water-splitting applications under solar light irradiation.