Ni-doped CoP/Co2P nanospheres as highly efficient and stable hydrogen evolution catalysts in acidic and alkaline mediums

Abstract The development of non-noble-metal catalysts plays a great role in production of hydrogen by water cracking. Here, we found the performance and efficiency of the transition metal phosphides for hydrogen evolution reaction (HER) can be improved by adjusting the morphology and electronic structure of electrocatalys. In this work, We have developed a kind of catalyst (Ni-doped CoP/Co2P NSs and starfish-like CoP/Co2P) with different morphologies. In electrochemical tests, Ni-doped CoP/Co2P NSs exhibits the excellent catalytic activity, showing that the overpotentials are only 100 ​mV (0.5 ​M ​H2SO4) and 125 ​mV (1 ​M KOH) for HER to afford the current density of 10 ​mA ​cm−2 and a Tafel slope of 66 ​mV dec−1 (0.5 ​M ​H2SO4) and 73 ​mV dec−1 (1 ​M KOH). Furthermore, Ni-doped CoP/Co2P NSs has great stability and robustness, which demonstrated by 12 ​h of chronoamperometry test and 3000 cycles test, showing that it maintains 98% (0.5 ​M ​H2SO4) and 93% (1 ​M KOH) of the current density of 10 ​mA ​cm−2. The reason for the excellent catalytic performance and robustness of Ni-doped CoP/Co2P NSs may be ascribed to the facts that the addition of Ni element leads to the change of material electron valence states, with synergistic effect with Co atoms, which possess outstanding performance of the catalyst.