Mn Doping of CoP Nanosheets Array: An Efficient Electrocatalyst for Hydrogen Evolution Reaction with Enhanced Activity at All pH Values

Heteratom doping is a possible way to tune the hydrogen evolution reaction (HER) catalytic capability of electrocatalysts. In this work, we report the development of Mndoped CoP (Mn-Co-P) nanosheets array on Ti mesh (Mn-Co-P/Ti) as an efficient 3D HER electrocatalyst with good stability at all pH values. Electrochemical tests demonstrate that Mn doping leads to enhanced catalytic activity of CoP. In 0.5 M H2SO4, this Mn-Co-P/Ti catalyst drives 10 mA cm-2 at an overpotential of 49 mV, which is 32 mV less than that for CoP/Ti. To achieve the same current density, it demands overpotentials of 76 and 86 mV in 1.0 M KOH and phosphate-buffered saline, respectively. The enhanced HER activity for Mn-Co-P can be attributed to its more thermo-neutral hydrogen adsorption free energy than CoP, which is supported by density functional theory calculations.