Three-dimensional nickel−cobalt oxide nanomaterials as enzyme-mimics electrocatalyst for the glucose and lactic acid oxidation reaction
Here we demonstrate a highly porous-structured three-dimensional nickel-cobalt oxide (NiCo2O4) nanomaterial as a potential glucose oxidase (GOx) enzyme-mimic catalyst for the electrochemical oxidation of glucose and lactic acid under alkaline medium. The as-synthesized NiCo2O4 nanomaterials based anode exhibits an excellent catalytic activity towards the glucose oxidation with a low oxidation potential of ~0.43 V (vs Ag/AgCl), a high current density of ~26.2 mA cm-2, high mass activity of ~263.0 Ag-1 and long term durability of over ~500 continuous cycles. The flower-like NiCo2O4 nanomaterials deliver an over ~1.4, ~1.9, ~2.0 times higher catalytic current density with a less positive shift by ~70 mV, ~80 mV and ~40 mV, respectively when compared to NiO, Co3O4, and commercial Pt/C. The enhanced catalytic activity of the as-developed Earth-abundant NiCo2O4 nanomaterial may be ascribed to its exclusive architecture with a less agglomerated structure, high electrochemical active surface area (ECASA), small pore size, mixed active sites of nickel and cobalt cations as well as an encouraging atmosphere for the enriched electron transfer process between analytes and electrodes. The present anode materials are competent in performing direct electron transfer to the surface of the electrode and remove the requirement for enzymes and mediators.