MOF-derived single-atom catalysts with dense zinc and nitrogen sites for efficient CO2 cycloaddition

Abstract

ZIF-8 derived Zn single-atom catalysts (SACs) bearing both acidic Zn and basic N sites are active for the cycloaddition of CO₂ with epoxides. However, their low Zn and N contents limit their catalytic activities. Herein, Zn SACs with dense N and Zn sites (hZn SAC-N) are prepared from ZIF-8 using zinc powder and melamine as the extra Zn and N sources, respectively. The Zn loading and N/C ratio are 15.12 wt% and 0.289, much higher than those of the Zn SAC obtained from ZIF-8 alone (5.11 wt% and 0.233). The catalytic activity of hZn SAC-N improves 2.55 times due to the abundant Zn and N sites. A much better catalytic stability of hZn SAC-N than that of ZIF-8 is also confirmed due to the highly stable carbonaceous single-atom structure. Our finding provides a useful strategy for enriching the active sites of SACs for various applications.