Trace of transition metal dopants induced charge redistribution on the MOF-derived CoP/NC electrocatalysts to improve water-splitting efficiency

Transition metal phosphides (TMPs) with similar catalytic mechanisms to hydrogenase usually suffer from sluggish reaction kinetics and limited durability for electrochemical water splitting because of their limited intrinsic catalytic activity and inevitable dissolution under extreme electrochemical reaction conditions. Herein, we employed trace transition metals (TM) as dopants to induce the charge redistribution of CoP for the optimization of the intermediate adsorption/desorption. Electrocatalysts composed of a trace TM modified CoP (denoted as TM-CoP, TM = Ni, Fe, Mn, Zn, Cu) nanoparticles anchoring on N-doped carbon were fabricated using a one-step low-temperature phosphorization. The introduction of TM atoms can modulate the electronic configuration of Co and P, and in-turns regulate the adsorption/desorption capacities of reactants. The carbon skeleton derived from ZIF-67 increases the efficiency of charge transfer/mass transport. The obtained Ni-CoP-2 (Ni: 2 wt%) catalyst possesses small overpotentials of 110 mV at 10 mA cm−2 in 0.5 M H2SO4 and 157 mV at 10 mA cm−2 in 1 M KOH electrolytes, respectively. In addition, a water splitting electrolyzer assembled by Ni-CoP-2 can reach 10 mA cm−2 at a low hydrolysis potential of 1.69 V. This work proposes an electronic structure tailoring approach through trace heteroatom involvement to improve catalytic activity for total hydrolysis.