An efficient ternary CoP2:XSe2(1- x) nanowire array for overall water splitting

Developing earth-abundant and efficient bifunctional electrocatalysts for realizing the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) under alkaline conditions is an intriguing challenge. Here, ternary necklace-like CoP2xSe2(1-x) nanowire arrays are synthesized via simultaneously phosphorizing and selenizing Co(OH)2 nanowires. Owing to the substitution of the P atom in the ternary system, the optimal electronic structure of CoP2xSe2(1-x) can be obtained and the stability can also be enhanced for hydrogen evolution. Thus, the ternary CoP2xSe2(1-x) NWs are highly active for electrochemical hydrogen evolution in both acidic and alkaline media, achieving a current density of 10 mA cm -2 at overpotentials of 70 mV and 98 mV, respectively. To realize the overall water splitting, we further performed the experiment using the CoP2xSe2(1-x) NWs as a cathode and Co(OH)2 NWs as an anode, which requires a cell voltage of 1.65 V to afford a water splitting current density of 10 mA cm -2 in strong alkaline media (1.0 M KOH).