Grafting amine-functionalized ligand layer on catalyst for electrochemical CO2 capture and utilization

Abstract

Direct electrochemical CO2 capture and utilization from flue gas offers appealing route to closing the carbon cycle and avoiding the cost for CO2 purification. Yet, the low CO2 concentration in flue gas and competing oxygen reduction reaction (ORR) pose severe challenges for this process. Herein, we report 4-aminobutylphosphonic acid ligand layer capped Ag nanoparticles (NH2BPA-Ag) for high-efficiency conversion of simulated flue gas (SFG). The amino group in NH2BPA is available for CO2 capture and activation, while phosphonic acid groups inhibit ORR by desorbing *OOH intermediate. NH2BPA-Ag achieves 82% CO Faradaic efficiency (FECO) in H-cell for SFG reduction and enhances FECO 2.6 times over pristine Ag nanoparticles. In a membrane electrode assembly electrolyzer, NH2BPA-Ag shows 79.6% FECO and 38.1% full-cell energy efficiency at 48 mA cm-2 for SFG conversion. This study highlights the strategy of tailoring catalytic microenvironments at molecular level for realizing a highly selective performance.