Recent Developments in Noble Metal-Free Catalysts for a Photocatalytic Water Splitting Process—A Review

Abstract

Sustainable hydrogen production is an essential prerequisite of a future hydrogen economy. Compared to other processes such as renewable energy-driven water electrolysis and photoelectrochemical water splitting, direct solar to hydrogen conversion through photocatalytic water splitting gives the simplest system for sustainable hydrogen production. Among the many factors to be considered such as the availability of solar radiation, gas collection mechanism and other infrastructure, a highly active noble metal-free photocatalyst is essential to make the water splitting process more energy efficient and economical. This review highlights the mechanism and factors hindering the efficiency of catalysts in photocatalytic water splitting, while discussing recent research efforts towards the development of highly efficient, noble metal-free photocatalysts, especially at the nanoscale, and their catalytic properties for water splitting. Mainly, catalysts consisting of TiO2, Z-schemed catalytic systems and naval computational approaches are discussed here. Moreover, techniques to enhance their catalytic activities and the developments required for the implementation of these photocatalytic systems at a commercial scale are further emphasized in the discussion section.