Coordination Environment Engineering to Regulate the Adsorption Strength of Intermediates in Single Atom Catalysts for High-performance CO2 Reaction Reduction.

Abstract

The modulation of the coordination environment of single atom catalysts (SACs) plays a vital role in promoting CO2 reduction reaction (CO2 RR). Herein, N or B doped Fe-embedded graphyne (Fe-GY), Fe-nXGYm (n = 1, 2, 3; X = N, B; m = 1, 2, 3), are employed as probes to reveal the effect of the coordination environment engineering on CO2 RR performance via heteroatom doping in SACs. The results show that the doping position and number of N or B in Fe-GY significantly affects catalyst activity and CO2 RR product selectivity. In comparison, Fe-1NGY exhibits high-performance CO2 RR to CH4 with a low limiting potential of -0.17V, and Fe-2NGY3 is demonstrated as an excellent CO2 RR electrocatalyst for producing HCOOH with a low limiting potential of -0.16V. With applied potential, Fe-GY, Fe-1NGY, and Fe-2NGY3 exhibit significant advantages in CO2 RR to CH4 while hydrogen evolution reaction is inhibited. The intrinsic essence analysis illustrates that heteroatom doping modulates the electronic structure of active sites and regulates the adsorption strength of the intermediates, thereby rendering a favorable coordination environment for CO2 RR. This work highlights Fe-nXGYm as outstanding SACs for CO2 RR, and provides an in-depth insight into the intrinsic essence of the promotion effect from heteroatom doping.