Interlayer-confined-enabled dual-site synergy strategy: A bilayer FeN4 catalyst for enhanced CO2 reduction and C-C coupling

Abstract

We propose a dual-active-site catalytic system with an interlayer confinement effect, inducing a vertical synergistic interaction to enhance CO₂ reduction reaction (CO₂RR) activity and selectivity. Using density functional theory (DFT) calculations, we systematically explore how interlayer distance influences CO₂ adsorption and key reaction intermediates. Our results reveal that confinement enhances electronic interactions, but excessive confinement induces steric hindrance, reducing catalytic activity. We identify two distinct carbon–carbon (CC) coupling mechanisms: a single-site adsorption pathway involving *CO desorption followed by *CO + *CO coupling and a dual-site adsorption pathway enabled by *CHO rotation and subsequent *CO + *CHO coupling. Strong confinement enhances dual-site coupling. The optimal interlayer distance for ethanol production is 6.5 Å (limiting potential: 0.7 V), while 7.5 Å favors CH₄ selectivity. This study establishes a theoretical framework for confined dual-site catalysis, providing design principles of interlayer-confined-enabled vertically aligned dual-site synergy approach for next-generation CO₂ electrocatalysts.