Microwave-assisted hydrothermal synthesis of MOFs-derived bimetallic CuCo-N/C electrocatalyst for efficient oxygen reduction reaction

Abstract

The oxygen reduction reaction (ORR) plays a significant role in energy conversion technologies such as metal-air batteries and fuel cells. The development of efficient ORR electrocatalyst is highly desirable to achieve the fast oxygen reduction. In this work, the bimetallic Cu and Co embedded nitrogen-doped carbon (CuCo-N/C) is fabricated as efficient electrocatalyst for ORR. The incorporation of Cu-precursor into Co-based zeolitic imidazolate frameworks (ZIF) is innovated here to synergistically enhance the activity of Co. Surprisingly, the addition of Cu can also increase the nitrogen content in the CuCo-N/C catalysts, which could generate more active sites and result in the improvement of ORR activity. The optimized CuCo-N/C catalysts exhibit superior ORR performance with a half-wave potential of 0.85 V (vs. RHE), a limiting current density of 5.61 mA cm−2 and enhanced long-term durability comparing with the state-of-the-art Pt/C catalysts. Benefiting from the unique structure, the as-made CuCo-N/C catalysts as electrode for Zn-air battery delivers excellent performance with a peak power density of 66.9 mW cm−2, a high open circuit voltage of 1.468 V, and a voltage degradation of about 1.4% after 12 h discharging, which is much better than that of Pt/C catalysts.