Cu-Co bimetal oxide hierarchical nanostructures as high-performance electrocatalyst for oxygen evolution reaction

Abstract

Electrochemical water splitting requires efficient and low-cost catalysts to accelerate the sluggish kinetics of the oxygen evolution reaction (OER). Nanostructural engineering is an effective way to achieve improved catalytic performance. Herein, hierarchical nanostructures consisting of porous nanofiber arrays on vertically aligned and interconnected copper-cobalt bimetal oxide nanoflakes are fabricated. The effect of annealing temperature and microstructure on the OER performance has been systematically investigated. The optimized sample exhibits a low overpotential of 293 mV at 10 mA/cm2, with a Tafel slope of 62 mV/dec for OER in an alkaline solution. Effect of nitrogen doping has also been investigated, which results in a further lowered overpotential of 265 mV at a current density of 10 mA/cm2 and a 60 mV/dec Tafel slope. This work demonstrates the effectiveness of nanocrystalline catalysts with rationally tuned hierarchical structures in enhancing the OER performance.