An efficient ternary CoPSe 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 CoPSe nanowire arrays are synthesized via simultaneously phosphorizing and selenizing Co(OH) nanowires. Owing to the substitution of the P atom in the ternary system, the optimal electronic structure of CoPSe can be obtained and the stability can also be enhanced for hydrogen evolution. Thus, the ternary CoPSe NWs are highly active for electrochemical hydrogen evolution in both acidic and alkaline media, achieving a current density of 10 mA cm at overpotentials of 70 mV and 98 mV, respectively. To realize the overall water splitting, we further performed the experiment using the CoPSe NWs as a cathode and Co(OH) NWs as an anode, which requires a cell voltage of 1.65 V to afford a water splitting current density of 10 mA cm in strong alkaline media (1.0 M KOH).