Single copper sites dispersed on hierarchically porous carbon for improving oxygen reduction reaction towards zinc-air battery

The demand for high-performance non-precious-metal electrocatalysts to replace the noble metal-based catalysts for oxygen reduction reaction (ORR) is intensively increasing. Herein, single-atomic copper sites supported on N-doped three-dimensional hierarchically porous carbon catalyst (Cu₁/NC) was prepared by coordination pyrolysis strategy. Remarkably, the Cu₁/NC-900 catalyst not only exhibits excellent ORR performance with a half-wave potential of 0.894 V (vs. RHE) in alkaline media, outperforming those of commercial Pt/C (0.851 V) and Cu nanoparticles anchored on N-doped porous carbon (CuNPs/NC-900), but also demonstrates high stability and methanol tolerance. Moreover, the Cu₁/NC-900 based Zn-air battery exhibits higher power density, rechargeability and cyclic stability than the one based on Pt/C. Both experimental and theoretical investigations demonstrated that the excellent performance of the as-obtained Cu₁/NC-900 could be attributed to the synergistic effect between copper coordinated by three N atoms active sites and the neighbouring carbon defect, resulting in elevated Cu d-band centers of Cu atoms and facilitating intermediate desorption for ORR process. This study may lead towards the development of highly efficient non-noble metal catalysts for applications in electrochemical energy conversion.