An overview of heteroatom doped cobalt phosphide for efficient electrochemical water splitting

Electrochemical water splitting is one of the most promising techniques for the sustainable production of green hydrogen. However, its large-scale commercialization is heavily dependent on high-performance and low-cost catalysts. CoP-based materials have received extensive attention among the candidates due to their good catalytic activity and bifunctional properties. The facile heteroatom-doping strategy can conveniently optimize the electronic and geometric structures of the active centers. In light of the significant advances in doped CoP-based materials, herein, we try to provide a comprehensive review of the effects of heteroatom-doping on CoP for water-splitting electrocatalysis. Firstly, the mechanisms of the half-reactions, the hydrogen/oxygen evolution reactions, have been briefly introduced with the combination of the density functional theory calculations and the spectroscopic analysis. Then the resulting promotions have been summarized that can improve the electrocatalysis performance through electronic effects and the formation of high valence active centers, as well as the structural effects. Recent progress about the CoP doped with the metal or/and non-metal elements is then discussed. It is concluded that heteroatom doping is a simple but efficient method to enhance the performance of CoP-based catalysts by optimizing the adsorption energy of the intermediates or changing the electronic structure. Moreover, the application of these catalysts as bifunctional catalysts for overall water splitting has also been briefly summarized. The prospects and challenges of CoP-based catalysts are shown from the viewpoint of mechanism exploration at the atomic scale and the industrial application at large scales. Hopefully, this review might be helpful to understand the catalysis and the catalyst development of doped CoP, and it would be also beneficial to developing other doped electrocatalysts.