Metal-doped nickel-based chalcogenides and phosphochalcogenides for electrochemical water splitting

The rational design of an affordable, stable, and active electrocatalyst is essential for a sustainable hydrogen economy. Recently, great progress has been achieved with nickel-based chalcogenides and phosphochalcogenides for both hydrogen and oxygen evolution reactions, and the metal doping strategy has been demonstrated to have a substantial impact on the performance of electrocatalysts. Common approaches to simultaneously improve the intrinsic activity of nickel-based (phospho)chalcogenides by metal doping and increase the active surface area of the electrocatalyst bring some challenges to deciding accurately whether metal doping will improve the electrocatalytic activity or not. This review highlights the influence of 3d block metal doping (Cu, Co, Fe and Mn) on the electrocatalytic performance of these phases with reference to the electronic structure of the materials. Such aspects as the electrical conductivity, hydrogen and oxygen intermediate adsorption mechanism, surface bifunctionality, role of chalcogenide/phosphochalcogenide surface functional groups, electrocatalytic stability and related changes upon metal doping are discussed in this review article. This work discusses current gaps that need to be filled to develop a systematic strategy in the modulation of the electronic/structural properties of metal-doped nickel-based (phospho)chalcogenides for their effective use in electrochemical water splitting. How does bimetallic composition of nickel-rich semiconductors affect their electrochemical water splitting activity?