Modulating the Electronic Structure of Zinc Single Atom Catalyst by P/N Coordination and Co2p Supports for Efficient Oxygen Reduction in Zn-Air Battery

Single-atom catalysts have emerged as effective active species for electrocatalysis because of their appropriate structural and electronic properties. However, the weight percentage of single metal atoms are generally below 5 wt% in the catalysts, limiting the population of catalytic sites and their performance. In this work, we synthesized Zn single atoms with a configuration of ZnN3P in the carbon framework. With the Co2P particles as supports (ZnCo-PNC), the generic Zn single atom catalysts with a content of only 2 wt% showed a half-wave potential of 0.91 V for oxygen reduction reaction in alkaline medium. This value is higher than that for pure P doped Zn and Co based catalysts (Zn-PNC of 0.69 V, Co-PNC of 0.82 V), and even better than commercial Pt/C (0.87 V). DFT results demonstrated that the synergistic promotion of Co2P supports and N/P coordination could reduce the energy barrier to proceed ORR on Zn single atoms from 1.85 to 0.79 eV. By using it as the cathode catalyst for zinc-air battery application, it shows respectable performance in terms of maximum peak power (237.3 mW cm−2) and energy densities (847 W h kg−1). The current strategy may open new horizons to design high performance single atom catalysts by using suitable supports and coordination environment to tune their activity.