Rational Design of Molybdenum‐Doped Cobalt Nitride Nanowire Arrays for Robust Overall Water Splitting

Abstract

AbstractRational design of efficient electrocatalysts is highly imperative but still a challenge for overall water splitting. Herein, we construct self‐supported Co3N nanowire arrays with different Mo doping contents by hydrothermal and nitridation processes that serve as robust electrocatalysts for overall water splitting. The optimal Co3N−Mo0.2/Ni foam (NF) electrode delivers a low overpotential of 97 mV at a current density of 50 mA cm−2 as well as a highly stable hydrogen evolution reaction (HER). Density functional theory (DFT) calculations prove that Mo doping can effectively modulate the electronic structure and surface adsorption energies of H2O and hydrogen intermediates on Co3N, leading to improved reaction kinetics with high catalytic activity. Further modification with FeOOH species on the surface of Co3N−Mo0.2/NF improves the oxygen evolution reaction (OER) performance benefiting from the synergistic effect of dual Co−Fe catalytic centers. As a result, the Co3N−Mo0.2@FeOOH/NF catalysts display outstanding OER catalytic performance with a low overpotential of 250 mV at 50 1 mA cm−2. The constructed Co3N−Mo0.2/NF||Co3N−Mo0.2@FeOOH/NF water electrolyzer exhibits a small voltage of 1.48 V to achieve a high current density of 50 mA cm−2 at 80 °C, which is superior to most of the reported electrocatalysts. This work provides a new approach to developing robust electrode materials for electrocatalytic water splitting.