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

Electrochemical water splitting requires efficient and low-cost catalysts to accelerate the sluggish ki-netics of the oxygen evolution reaction (OER). Nanostructural engineering is an effective way to achieve improved catalytic performance. Herein, hierarchical nanostructures consisting of porous nanofiber ar-rays 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/cm(2), 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/cm(2) 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. (c) 2021 Elsevier Ltd. All rights reserved.