Steering proton-coupled electron transfer via phosphorus-modulated iron atoms for efficient CO2RR

P-modulated Fe single atoms are designed to steer interfacial PCET pathways. • Remote P-doping reconfigures interfacial water networks for optimal proton supply. • In situ spectra and simulations reveal accelerated *COOH formation kinetics. • The FeNPC catalyst achieves a remarkable CO Faradaic efficiency of 98.68%. In electrocatalytic CO₂ reduction reaction (CO₂RR), the rate-determining formation of the key *COOH intermediate requires a facile and moderate proton supply, yet excessive water activation generates abundant adsorbed hydrogen (*H) that triggers the competing hydrogen evolution reaction (HER) and diminishes CO selectivity. Here, we develop a phosphorus-doped Fe single-atom catalyst (FeNPC) to steer interfacial proton-coupled electron transfer (PCET) pathways. P incorporation reconstructs the interfacial hydrogen-bonding network, selectively enriching weakly hydrogen-bonded and free water molecules to ensure an optimal proton supply for *COOH generation while suppressing excessive *H accumulation. In-situ ATR-SEIRAS characterization confirms enhanced *COOH signals, and MD/DFT calculations reveal that P-doping lowers activation barriers for water dissociation and *COOH formation. Consequently, FeNPC achieves a CO Faradaic efficiency of 98.68% at −0.4 V vs. RHE with reliable stability. This work demonstrates that nonmetallic doping optimizes PCET kinetics by reshaping the interfacial water microenvironment, establishing a new paradigm for designing highly-selective CO₂RR electrocatalysts. Download: Download high-res image (273KB) Download: Download full-size image