Advances in photochemical splitting of seawater over semiconductor nano-catalysts for hydrogen production: A critical review

The production of sustainable fuel such as hydrogen (H2) from vast natural resources including seawater and solar irradiation has caught the interest. Such continued initiative towards utilizing ideal strategies harnessing photochemical processes to facilitate water splitting could efficiently reduce fossil fuels consumption. While it has been more than a half-century since Fujishima introduced photochemical water splitting, this research has continued to focus on this central. Extensive efforts have been exploited using different semiconductors as photocatalysts by exploiting the fresh water resource for hydrogen production. The existence of various ions in seawater is a barrier to efficient H2 production via photocatalytic splitting and, thus is a major obstacle for researchers to overcome. This review aims at the process of splitting seawater photochemically and the challenges of using direct seawater for hydrogen production. Subsequently, the band structure of semiconductor catalysts, reaction conditions, and mechanisms for splitting seawater are analyzed. Furthermore, potential photochemical catalysts for hydrogen production are proposed. This review provides the key scientific advances in the field of photochemical water splitting over the recent past highlighting major hindrances and obvious prospects towards the eventual goal of attainment of highly sustainable, large-scale green fuel production in the form of hydrogen on a single platform.