Engineering Strategy for Enhancing the Co Loading of Co-N₄-C Single-Atomic Catalysts Based on the ZIF-67@Yeast...

The Co-N₄-C single-atom catalysts (SACs) have attracted great research interest in the energy storage and conversion fields owing to 100% atom utilization. However, enhancing the Co loading for higher electrocatalytic performance is still challenging. In this context, we propose an engineering strategy to fabricate the high Co atomic loading Co-N₄-C SACs based on the zeolitic imidazolate framework-67 (ZIF-67)@yeast construction. The rich amino groups provide the possibility for Co²⁺ ion anchorage and ZIF-67@yeast construction via the biomineralization of yeast cells. The functional design induces the formation of Co-N₄-C sites and regulates the porosity for exposure of such Co-N₄-C sites. As a result, the Co-N₄-C sites were anchored on spherical micrometer flower carbonaceous materials through our novel strategy. The as-obtained optimal sample exhibited a Co atomic loading of 12.18 wt % and a specific surface area of 403.26 m² g^-1. High Co atomic loading and large specific surface area delivered excellent electrocatalytic kinetics as well as a high discharge voltage of 1.08 V at 10 mA cm^-2 for more than 100 h in Zn-air batteries. This work represents a promising strategy for fabricating high-loading SACs with high activity and good durability.