l -Arginine-Modified Ag Catalyst Enabling Efficient Low-Concentration CO 2 Capture and Electroreduction to CO

Direct electrocatalytic reduction of low-concentration CO 2 (CO 2 RR) to high-value CO provides an effective pathway for reducing the costs associated with CO 2 capture, separation, and conversion. However, the CO 2 RR efficiency is often limited by insufficient mass transfer under low concentrations of CO 2 . Here, we developed an l -arginine-functionalized Ag catalyst (LA-Ag), achieving significantly enhanced CO 2 RR performance under 1 vol % CO 2 condition. At a cell potential of −2.7 V, the 10% LA-Ag catalyst presented more than 10 times efficiency compared to the unmodified Ag catalyst, with the CO yield of 7.72 mmol·h –1 ·g –1 and a Faradaic efficiency of 17.4%. Moreover, l -arginine modification improved the energy efficiency and substantially lowered energy consumption to 0.021 kw·h/mol CO. Comprehensive characterization revealed that the strong electronic interaction between l -arginine and Ag nanoparticles effectively regulated interfacial charge distribution and accelerated electron transfer. Combined density functional theory (DFT) calculations and TPD analysis demonstrated that the guanidine functional group in l -arginine greatly contributed to capturing low-concentration CO 2, boosting the CO 2 adsorption and activation. This work presents a promising strategy for designing efficient catalysts for direct low-concentration CO 2 RR.