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

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-N-4 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-N-4 sites are likely active centers for the CO2ER. Theoretical calculations reveal the synergistic effects of S and Zn-N-4 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.

Automated summary

Improving the proton transfer rate is crucial for accelerating the reaction kinetics of CO2 electroreduction (CO2ER). A zinc-nitrogen-sulfur co-doped carbon catalyst with isolated zinc and adjacent sulfur dopants was developed for CO2ER. The sulfur sites enhance bicarbonate dissociation for proton feeding, while the zinc-nitrogen sites serve as active centers for CO2ER. The synergistic effects of sulfur and zinc-nitrogen sites improve the proton transfer rate and boost the reaction kinetics. This catalyst exhibits excellent CO2ER performance with high CO selectivity and turnover frequency.