Accelerating industrial-level CO2 electroreduction kinetics on isolated zinc centers via sulfur-boosted bicarbonate dissociation

Abstract

Improving the proton transfer rate in the proton-coupled electron transfer process is the key to accelerating the reaction kinetics of CO₂ electroreduction (CO₂ER). However, the synchronous enhancement of proton feeding and CO₂ activation are hardly achieved over the single active site, making rapid conversion with high product selectivity a considerable challenge. Herein, we develop an isolated zinc site embedded in nitrogen, sulfur co-doped hierarchically porous carbon (denoted as Zn–NS–C) electrocatalyst toward CO₂ER, in which central Zn–N₄ active sites are associated with adjacent S dopants in Zn–NS–C. Kinetic experiments combined with in situ spectroscopy unveil that the auxiliary S sites promote bicarbonate dissociation kinetics for proton feeding and atomically dispersed Zn–N₄ sites are likely active centers for the CO₂ER. Theoretical calculations reveal the synergistic effects of S and Zn–N₄ sites that improve the proton transfer rate and boost the reaction kinetics of *CO₂ protonation to form *COOH. As a result, this catalyst delivers an excellent CO₂ER performance with near-unity CO selectivity at an industrial-level current density of 200 mA cm⁻² and a high turnover frequency of 11 419 h⁻¹. Furthermore, the high CO productivity on the Zn–NS–C was confirmed by the highly increased partial C₂H₄ current density in the Zn–NS–C/Cu tandem catalyst.