Ni2P-Co2P Nanowire Arrays on Nickel Foam as a Robust pH- Universal Electrocatalyst for High-Efficiency Hydrogen Evolution Reaction

Splitting water to produce hydrogen through an efficient and low-cost way requires the development of catalysts based on earth-abundant elements. Among transition metal phosphides, bimetal phosphides demonstrate superior hydrogen evolution reactivity to monometal phosphides. Therefore, we synthesized Ni2P-Co2P nanowire arrays on nickel foam with excellent catalytic performance by hydrothermal and low-temperature phosphorization. In 1 M KOH, the catalyst demonstrates low overpotentials of 99 and 161 mV to reach current densities of 10 and 100 mA cm(-2), respectively. In 0.5 M H2SO4, the overpotentials of Ni2P-Co2P are only 94 and 159 mV at current densities of 10 and 100 mA cm(-2), respectively. In a neutral solution, the overpotentials of the catalyst are also only 146 and 309 mV at current densities of 10 and 100 mA cm(-2), respectively. The Tafel slopes of Ni2P-Co2P are only 53.1, 48.26, and 138.3 mV dec(-1) in acid, alkaline, and neutral solutions, respectively. Moreover, the outperformance of its durability was tested for 20 h in acid and alkaline solutions, which maintained a stable current density of 10 mA cm(-2). This work demonstrates a feasible route to design transition metal phosphides used in pH-universal HER electrocatalysts.

Automated summary

Ni2P-Co2P nanowire arrays synthesized by hydrothermal and low-temperature phosphorization on nickel foam exhibit excellent catalytic performance with low overpotentials and high current densities in acidic, alkaline, and neutral solutions.