High-efficiency Ni-P catalysts with amorphous and crystalline states on hydrogen evolution reaction

As a kind of catalysts with great development potential, the nickel-phosphorus (Ni-P) catalyst is widely concerned. However, the difference between the amorphous and the crystalline Ni-P electrodes in the hydrogen evolution still lacks the necessary research. Herein, an amorphous Ni-P electrode was prepared by a method of cathodic electrodeposition, which showed excellent catalytic performance that can achieve a HER current densities of 10 mA cm-2 in 1.0 M KOH solution at an overpotential of 50 mV. Meanwhile, it was converted to a crystalline Ni-P electrode by annealing under vacuum. On this basis, we have compared the differences of the catalytic performance of the crystalline and amorphous Ni-P electrodes in the alkaline and acid environment. It was found that amorphous Ni-P showed excellent hydrogen evolution catalytic performance in alkaline electrolytes, which was mainly due to the better hydrophilicity and higher inherent catalytic activity of the amorphous state. But it was not stable, so the performance was not satisfactory in acidic solution. On the other hand, the inherent catalytic activity and hydrophilicity of crystalline Ni-P is somewhat worse than that of amorphous Ni-P, and the catalytic performance was not as good as the latter, but due to the stable chemical state, crystalline Ni-P had better stability in acidic solutions.