Tuning Electronic Structure of CuCo2O4 Spinel via Mn-Doping for Enhancing Oxygen Evolution Reaction

Abstract

Cobalt-based spinel oxide is a promising electrocatalyst for oxygen evolution reaction (OER) because of its low cost, excellent activity and stability. Herein, we designed the CuMnxCo2O4 electrocatalyst with tunable electronic structure via Mn-doping to enhance OER performance. Results showed that the CuMn0.5Co2O4 catalyst prepared by calcined at 600°C exhibited high crystalline without impurity phase, and possessed the enhanced Co2+/Co3+ ratio and high concentration of oxygen vacancies, which were facilitated to enhance OER performance. Electrochemical test results showed the CuMn0.5Co2O4 catalyst had high OER performance with a low overpotential of 340 mV at the current density of 10 mA ⋅ cm−2 and a smaller Tafel slope of 69.8 mV ⋅ dec−1. TOF and ECSA results illustrated that the more intrinsic catalytic activity on the CuMn0.5Co2O4 catalyst. After 1000 cycles, the catalyst exhibited high stability with the 8 1.7 % of current retention rate. The OER activity enhancement mechanism of was further analyzed, which were mainly ascribed to the conversion of variable Co2+/Co3+ and enhanced oxygen vacancies.