Performance Enhancement Of NiCo₂O₄ Nanorods For Overall Water Splitting By N-doped Carbon

Hydrogen fuel acquired from electrochemical water splitting is one of the most encouraging ways for the quick raise of global energy need and resulted in a clean and sustainable energy resource with zero carbon footprints in the environment.The key to realize this purpose is the investigation of solid earth-numerous materials and cost-efficient reaction processes that can catalyze both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)with high efficiency and stability.One-dimensional(1D)nanomaterials and nanostructures have been substantially investigated for their potential of decreasing the overpotentials and increasing catalytic activity,which benefited from their high electrochemically active surface area,quick charge transfer,effective mass transport of reactant species,and efficient release of gas generated.Herein 1D NiCo2O4 nanorods were fabricated both for HER and OER in this work.Furthermore,the performance was greatly enhanced by coating a layer of N-doped carbon.The obtained NiCo2O4@N-doped carbon supported on Ni foam shows superior catalytic activity toward the hydrogen evolution reaction(HER)with an overpotential of 122 mV at 10 mA cm-2 in alkaline media.Moreover,it is also capable of catalyzing the oxygen evolution reaction(OER)with overpotential of 270 mV at 10 mA cm-2.Finally,the electrode of NiCo2O4@N-doped carbon nanorods was used both as the cathode and anode for overall water splitting,a current density of 10 mA cm-2 achieved at a cell voltage as low as 1.626 V.In addtion,the NiCo2O4@N-doped carbon achieved very good stability at long-term test.The potential at a constant current density of 10 mA cm-2 only increased from 1.777 to 1.781 V after 24 h.