A Pulsed Tandem Electrocatalysis Strategy for CO2 Reduction

Electroreduction of CO2 to value-added C2 products remains hindered by sluggish C-C coupling kinetics and competing side reactions. Inspired by the tandem catalytic mechanisms of multienzyme systems, we designed a dual-site single-atom nanozyme (DSAN) comprising FeN4 and FeO4 sites (FeN4-FeO4). Density functional theory (DFT) calculations under constant potential reveal that the FeN4 site functions as a CO generator, while the FeO4 site facilitates CO migration, C-C coupling, and subsequent C2 product formation. To further optimize the catalytic efficiency, we introduced a pulsed electrocatalysis strategy by alternating between zero potential and -0.7 V. This approach dynamically modulates active-site functions: at -0.70 V, CO2 adsorption and *CH3CH2OH formation are facilitated, while at 0 V, CO migration and C-C coupling are enhanced due to the spin-state transitions during potential switching. Additionally, the zero potential suppresses excessive hydrogenation of key intermediates, thereby improving CH3CH2OH selectivity. These findings highlight the synergistic strategy integrating tandem catalysis and pulsed potential control, offering a novel and effective approach for CO2-to-C2 conversion using SAN catalysts.