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.