Nickel-doped Co4N nanowire bundles as efficient electrocatalysts for oxygen evolution reaction

Cost-efficient electrocatalysts composed of earth-abundant elements are highly desired for enhanced oxygen evolution reaction (OER). As a promising candidate, metallic Co4N already demonstrated electrocatalytic performance relying on specific nanostructures and electronic configurations. Herein, nickel was introduced as the dopant into one-dimensional (1D) hierarchical Co4N structures, achieving effective electronic regulation of Co4N toward high OER performance. The amount of Co3+ increased after Ni-doping, and the in-situ formed surface oxyhydroxide during OER enhanced the electrocatalytic kinetics. Meanwhile, the 1D hierarchical structure further promoted the performances of Co4N owing to the high electrical conductivity and abundant active-sites on the rough surface. As expected, the optimal Ni-doped Co4N with a Ni/Co molar ratio of 0.25 provides a small overpotential of 233 mV at a current density of 10 mAcm−2, with a low Tafel slope of 61 mV dec−1, and high long-term stability in 1.0 mol L−1 KOH. Following these results, the enhancement by doping the Co4N nanowire bundles with Fe and Cu was further evidenced for the OER.