Design of Cobalt Nickel Nitrides/carbon Nitride Composite Catalysts for Enhanced Electrochemical Water Splitting

Design of efficient non-noble metal electrocatalysts for oxygen evolution reaction (OER) have been considered as a crucial issue in the development of future renewable energy utilization. In this paper, we report a composite structure of cobalt nickel nitrides and carbon nitrides as efficient OER electrocatalysts. A facile hydrothermal method was utilized to synthesize the precursors, then the samples were treated with melamine and heated in an N2 atmosphere. The successful preparation of the cobalt nitride nickel/carbon nitride composite catalysts was confirmed by SEM, XRD, and the OER electrochemical performance characterizations. The Co2NiNx/CN catalyst demonstrate an optimal electrocatalytic performance with an overpotential of 0.62 V to reach the current density of 10 mA/cm2, which is lower than that of Ni3N, Ni3N/CN and Co2NiNx. The Tafel slope of Co2NiNx/CN catalyst is only 83.68 mV/dec. The significantly improved electrocatalytic ability is owing to the synergetic effect of cobalt incorporation and imbedding of carbon nitride. The electrochemical impedance spectroscopy characteristics were further investigated to understand the mechanism of the novel non-noble metal electrocatalysts with high efficiency.