Influence of Interfacial Engineering of NiC/Co₂C Enables Unlocking Efficiency of Water Oxidation

Developing a scalable synthetic route to first row metal catalysts becomes a major target in hydrogen production where the unlocking of a catalytic activity source is vital to designing efficient catalysts. Herein we report an efficient bimetallic carbide, NiC/Co2C, using a mechanochemical–magnesiothermic reduction (MC–MTR) process for oxygen evolution reaction (OER), having an unusual lamellar nanoplates assembled tunnels morphology. The well-oriented lamellar nanoplate assembled tunnels provide high porosity with a large surface area to accelerate mass transport and effective contact with the electrolyte and generate a less tortuous path for charge distribution, thus enhancing the charge homogeneity. Remarkably, NiC/Co2C demands a low overpotential of 271 mV with a Tafel slope of 54 mV dec–1 and shows no degradation for continuous operation over 8 h. A proficient electrolyzer was constructed using NiC/Co2C as anode, achieving 10 mA cm–2 at 1.54 V. During the OER process, NiC induced a rapid phase transition of cobalt into CoOOH* and formed a nickel-rich surface of defective CoOOH*, which significantly enhanced the OER kinetics. The phase transition to CoOOH* with nickel-rich-surface reconstruction is augmented at 1.54 V, as revealed by post SEM and TEM studies. Also methanol oxidation by NiC/Co2C inferred that the nickel enrichment on the defective CoOOH* surface stimulates electron flow from Ni to Co sites via bridging oxygen, benefiting electrostatic adsorption of OH– followed by a consequential OER process. Thus, great catalytic efficiency with suitable durability make it one of the topmost effective OER electrocatalysts.