Nickel selenides as pre-catalysts for electrochemical oxygen evolution reaction: A review

Nickel selenide is an important class of nickel chalcogenide that has recently gained greater attention in electrochemical water splitting. Though other chalcogenides such as sulphides and tellurides have also been shown to possess appreciable electrocatalytic water splitting activity as both cathode and anode material, the electrocatalytic activity of nickel selenides in oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is unmatched by the former one. In the case of HER, nickel selenides are good electrocatalysts in both acid and alkali with some metal dissolution in acid and surface modification to nickel hydroxide in alkali. In the case of OER, nickel selenides have been shown to behave in a unique way in which it acted better than simple nickel hydroxides/oxyhydroxides. This is quite intriguing to researchers and many studies have been recently carried out. However, there is still no exclusive review summarizing the recent development of this material for OER electrocatalysis with highlights on challenges and opportunities. Hence, we have dedicated to discuss the same in this review. In addition, the significance of OER electrocatalysis has been briefly introduced. Finally, all the studies that reported the OER activity of nickel selenides are benchmarked based on the Tafel slope values. With the collective information provided in this review, readers would be updated with the recent trend in utilizing nickel selenides as OER electrocatalysts.