Molybdenum-Doped Porous Cobalt Phosphide Nanosheets for Efficient Alkaline Hydrogen Evolution

Electrocatalytic water splitting allows the production of high-purity and industrially affordable hydrogen fuel. However, the lack of highly active and robust non-noble-metal electrocatalysts has hindered the at-scale production of hydrogen for years. Here, nickel foam supported porous Mo-doped CoP nanosheets (pCoMo-P/NF) are employed as an alkaline electrocatalyst for the hydrogen evolution reaction (HER), which was obtained from CoMoAl layered triple hydroxides (CoMoAl-LTH) derived phosphides with dissolved Al species. The unique advantage in such a synthesis process is that the introduced Mo and Al elements in the Co(OH)(2) matrix efficiently prevent the aggregation of doped CoP nanocrystals during high temperature phosphorization. Then, because of the optimized electronic structure for accelerating H* adsorption after Mo doping, as well as the increased electrochemically active surface area and decreased electrode/electrolyte interfacial resistance after dissolution of the Al species, such a pCoMo-P/NF electrocatalyst requires only 49 mV overpotential to drive 10 mA cm(-2) current density in 1.0 M KOH. Additionally the electrocatalyst demonstrates prolonged stability with negligible activity decay after 3000 cycles of a cyclic voltammetry test or chronopotentiometric measurement under a static overpotential of 100 mV for 10 h. This work not only provides a synergistic strategy to design both an efficient and durable HER electrocatalyst, but also investigates the crucial elemental doping effects in phosphide electrocatalysts as well as in the transition of hydroxides to phosphides.