NiCo2Se4 Nanowires as a High-Performance Bifunctional Oxygen Electrocatalyst

Abstract

Rechargeable zinc–air batteries are attracting great attention due to their high theoretical specific energy, safety, and economic viability. However, their performance and large-scale practical applications are largely limited by poor durability and high overpotential on the air-cathode due to the slow kinetics of the oxygen evolution and reduction reactions (OER/ORR). Therefore, it is highly desired to develop new bifunctional catalysts to improve the OER and ORR kinetics. In this paper, NiCo2Se4 nanowires were uniformly grown on carbon fiber paper (CFP) for the first time. With an overpotential for OER of 327 mV, NiCo2Se4 nanowires show a better performance than RuO2 (350 mV) and a high stability. Moreover, their half-wave potential of 0.77 V and limiting current density of 3.75 mA·cm−2 make it a promising non-precious-metal catalyst for ORR, with performance close to Pt/C (0.87 V, 3.7 mA·cm−2). The excellent performance is attributed to the nanowire morphology with efficient 1D electronic pathways, high conductivity of NiCo2Se4 and an enhanced electronic structure, thanks to a mixed valence of nickel and cobalt ions.