Near- and Long-Range Electronic Modulation of Single Metal Sites to Boost CO2 Electrocatalytic Reduction.

Abstract

Tuning the electronic structure of the active center is effective to improve the intrinsic activity of single-atom catalysts but the realization of precise regulation remains challenging. Herein, a strategy of "synergistically near- and long-range regulation" is reported to effectively modulate the electronic structure of single-atom sites. ZnN4 sites decorated with axial sulfur ligand in the first coordination and surrounded phosphorus atoms in the carbon matrix are successfully constructed in the hollow carbon supports (ZnN4 S1 /P-HC). ZnN4 S1 /P-HC exhibits excellent performance for CO2 reduction reaction (CO2 RR) with a Faraday efficiency of CO close to 100%. The coupling of the CO2 RR with thermodynamically favorable hydrazine oxidation reaction to replace oxygen evolution reaction in a two-electrode electrolyzer can greatly lower the cell voltage by 0.92V at a current density of 5mA cm-2 , theoretically saving 46% of energy consumption. Theoretical calculation reveals that the near-range regulation with axial thiophene-S ligand and long-range regulation with neighboring P atoms can synergistically lead to the increase of electron localization around the Zn sites, which strengthens the adsorption of *COOH intermediate and therefore boosts the CO2 RR.