Accelerating the surface reconstruction of cobalt phosphide via dual-doping engineering for high-performance water electrolysis

Most transition metal compound electrocatalysts would undergo potential-dependence phase conversion to generate actual active phase of anodic water oxidation. However, the dependence of high potential in electrochemical self-reconstruction, as well as the sluggish dynamics of water oxidation reaction are the main obstacles to real catalytic origins exploration and large-scale hydrogen fuel production. Herein, for the first time, sulfur and nickel dual-doped cobalt phosphide nanowire arrays (CoP3NiS NAs) are rationally designed as pre-catalysts, in which the S anions accelerate the surface reconstruction of the CoP3 while the Ni cations enhance the activity and selectivity of oxygen evolution reaction (OER). The converted products (CoP3NiS-R NAs) exhibit the overpotential of only 260 mV at 100 mA cm−2 for OER, much superior to the CoP3-R NAs and the benchmark IrO2. In addition, the two-electrode electrolyser (CoP3NiS@CoP3NiS-R) presents an ultra-low cell voltage of 1.47 V at 10 mA cm−2 and extraordinary durability over 120 h. This work elucidates the rational design of bifunctional materials in energy devices, and demonstrates that the electrochemical self-reconstruction engineering of cobalt-based phosphides is a promising strategy to design highly-efficient OER electrocatalysts.