A Pulsed Tandem Electrocatalysis Strategy for CO Reduction.

Electroreduction of CO to value-added C 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 FeN and FeO sites (FeN-FeO). Density functional theory (DFT) calculations under constant potential reveal that the FeN site functions as a CO generator, while the FeO site facilitates CO migration, C-C coupling, and subsequent C 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, CO adsorption and *CHCHOH 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 CHCHOH selectivity. These findings highlight the synergistic strategy integrating tandem catalysis and pulsed potential control, offering a novel and effective approach for CO-to-C conversion using SAN catalysts.