Breaking the current density bottleneck in electrochemical CO2 reduction reaction via high-pressure operated Sn single-atom catalysts

Pressure engineering overcomes CO 2 mass-transfer limitations and enhances eCO 2 RR performance. • SnN 4 single-atom catalysts achieve 85% FE HCOOH and high current density under 5 MPa CO 2 . • In situ IR and DFT reveal pressure-induced *OCHO stabilization for selective formate production. Electrochemical carbon dioxide reduction reaction (eCO 2 RR) in aqueous media is fundamentally constrained by the low solubility of CO 2 , leading to limited current densities and poor product selectivity. Herein, we have developed tin single-atom catalysts (Sn-SACs) featuring well-defined SnN 4 coordination as a platform to systematically investigate the influence of CO 2 pressure on reaction kinetics and selectivity. Elevating the CO 2 pressure to 5 MPa markedly enhances mass transport, achieving a Faradaic efficiency for formate of 85% at −1.1 V vs. RHE with high current density, in stark contrast to 11.5% under 0.1 MPa. In situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) reveals that high pressure favors the formation of *OCHO intermediates, thereby redirecting the reaction pathway toward formate production. Complementary density functional theory (DFT) calculations corroborate that increased local CO 2 concentration stabilizes the *OCHO transition state and lowers the associated energy barrier. This work has established that pressure engineering as an effective strategy to decouple mass transport, activity, and selectivity in eCO 2 RR, underscoring the promise of high-pressure electrochemistry for efficient CO 2 conversion. Download: Download high-res image (304KB) Download: Download full-size image