A feasible strategy for designing cytochrome P450-mimic sandwich-like single-atom nanozymes toward electrochemical CO₂ conversion

Carbon dioxide electroreduction (CO₂ER) presents a promising strategy for environmentally friendly CO₂ utilization due to its low energy consumption. Single-atom nanozymes (SANs), amalgamating the benefits of single-atom catalysts and nanozymes, have become a hot topic in catalysis. Inspired by the intricate structure of cytochrome P450, we designed 81 sandwich-like SANs using Group-VIII transition metals (TMN₄-S-TM'N₄) and evaluated their performance in CO₂ER using density functional theory (DFT). Our investigation revealed that most SANs display superior catalytic activity and improved specific product selectivity in comparison to the Cu (211) surface. Notably, IrN₄-S-TMN₄ (TM = Co, Rh, Pd) exhibited selective CO₂ reduction to CO with remarkable limiting potentials (U_L) of -0.11, -0.07, and -0.09 V, respectively, demonstrating potential as artificial CO dehydrogenases. Furthermore, RuN₄-S-RuN₄ exhibited formate dehydrogenase-like activity, resulting in selective production of HCOOH at a U_L of -0.10 V. Machine learning analysis elucidated that the exceptional activity and selectivity of these SANs stemmed from precise modulation of electron density on sulfur atoms, achieved by varying transition metals in the subsurface. Our research not only identifies exceptional SANs for CO₂ER but also provides insights into innovative methods for regulating non-bonding interactions and achieving sustainable CO₂ conversion.