Surface engineering by doping manganese into cobalt phosphide towards highly efficient bifunctional HER and OER electrocatalysis

Developing highly efficient and sustainable bifunctional cheap electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is crucial, but remains a challenge for large-scale water splitting applications. Appropriate surface engineering of non-noble metal electrocatalysts is essential for tuning their electrocatalytic properties. Herein, MnCoP nanosheets are designed and constructed by doping Mn into CoP via direct one-step electrodeposition on carbon cloth. Doping Mn can not only modify the surface electronic structure of CoP, but also enhance electrochemical surface areas (ECSA) to expose more accessible active sites, and increase the intrinsic activity for HER and OER. As a result, the electrocatalyst reasonably shows superior catalytic performance: the overpotential is as low as 65 mV for HER and 261 mV for OER in 1 M KOH solutions to deliver the current density of 10 mA cm−2, along with outstanding stability benefited from the strong affinity between the catalyst and CC substrate. The electrolyzer cell for overall water splitting, using MnCoP/CC as both anode and cathode catalysts, exhibits a very low voltage of 1.62 V at 10 mA cm−2 and excellent long-term durability within 24 h. This study offers a general method to produce high-performance and cost-effectiveness catalysts for water splitting and other catalytic fields.