Ni-based Electro/Photo-Catalysts in HER – A Review

Designing active and stable non-precious electro and photocatalyst for water splitting reaction is a blistering area of research. Ni, belonging to the group of Pt (the most active catalytic material), is widely exploited for HER. As the activity order is Pt˃Pd˃Ni, much attention has been devoted to exploring and enhancing the best from Ni. Therefore various Ni compounds and composites are studied for their catalytic action. In photocatalysis, Ni is exploited more as a co-catalyst rather than as catalyst. In electrocatalysis, Ni compounds and their composites are used to modify the cathode of the electrolyzer. The present review explores the impact of Ni-based materials in hydrogen production through electro and photocatalytic water splitting process. Herein, the core theory of electro/photocatalytic water-splitting reaction is incorporated. The desired features of electro/photocatalyst and factors controlling their activity are demonstrated citing examples. A thorough literature survey has been done to identify the advanced strategies employed for elevating the performance of Ni and its compounds as electro and photocatalyst. Also, the probable electro/photo catalytic mechanisms by which various Ni-based materials evolve hydrogen are demonstrated via their schematic representations. Major challenges involved in Ni-based electro/photocatalysis are discussed. "The trend and potential" section identify the current trend and future direction in the area. The concluding section well summarizes the findings. The present article can work as an insightful reference and a leading guide for beginners and experts in the field of renewable energy.