Electro-activated indigos intensify ampere-level CO2 reduction to CO on silver catalysts
Zhengyuan Li, Xing Li, Ruoyu Wang, Astrid Campos Mata, Carter S. Gerke, Shuting Xiang, Anmol Mathur, Lingyu Zhang, Dian‐Zhao Lin, Tianchen Li, Krish N. Jayarapu, Andong Liu, Lavanya Gupta, Anatoly I. Frenkel, V. Sara Thoi, Pulickel M. Ajayan, Soumyabrata Roy, Yuanyue Liu, Yayuan Liu, Yayuan Liu, Yayuan Liu
Abstract
The electrochemical reduction of carbon dioxide (CO2) to carbon monoxide (CO) is challenged by a selectivity decline at high current densities. Here we report a class of indigo-based molecular promoters with redox-active CO2 binding sites to enhance the high-rate conversion of CO2 to CO on silver (Ag) catalysts. Theoretical calculations and in situ spectroscopy analyses demonstrate that the synergistic effect at the interface of indigo-derived compounds and Ag nanoparticles could activate CO2 molecules and accelerate the formation of key intermediates (*CO2– and *COOH) in the CO pathway. Indigo derivatives with electron-withdrawing groups further reduce the overpotential for CO production upon optimizing the interfacial CO2 binding affinity. By integrating the molecular design of redox-active centres with the defect engineering of Ag structures, we achieve a Faradaic efficiency for CO exceeding 90% across a current density range of 0.10 − 1.20 A cm–2. The Ag mass activity toward CO increases to 174 A mg–1Ag. This work showcases that employing redox-active CO2 sorbents as surface modification agents is a highly effective strategy to intensify the reactivity of electrochemical CO2 reduction. It is challenging to maintain the CO selectivity under high current densities in CO2 electro-reduction process. Here the authors report the synergistic interface between redox active CO2 organic sorbents and defective Ag catalysts that can enable an ampere level CO2-to-CO conversion.