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

Graphical A novel self-supported Co 3 N nanowire arrays with Mo doping is designed by the hydrothermal and nitridation processes, serving as excellent electrocatalysts for overall water splitting. The constructed Co 3 N−Mo 0.2 /NF||Co 3 N−Mo 0.2 @FeOOH/NF electrolyzer exhibits a small voltage of 1.48 V to achieve 50 mA cm −2 at 80 °C, which is superior to most of the reported electrocatalysts. Rational design of efficient electrocatalysts is highly imperative but still a challenge for overall water splitting. Herein, we construct self-supported Co 3 N nanowire arrays with different Mo doping contents by hydrothermal and nitridation processes that serve as robust electrocatalysts for overall water splitting. The optimal Co 3 N−Mo 0.2 /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 H 2 O and hydrogen intermediates on Co 3 N, leading to improved reaction kinetics with high catalytic activity. Further modification with FeOOH species on the surface of Co 3 N−Mo 0.2 /NF improves the oxygen evolution reaction (OER) performance benefiting from the synergistic effect of dual Co−Fe catalytic centers. As a result, the Co 3 N−Mo 0.2 @FeOOH/NF catalysts display outstanding OER catalytic performance with a low overpotential of 250 mV at 50 1 mA cm −2 . The constructed Co 3 N−Mo 0.2 /NF||Co 3 N−Mo 0.2 @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.