Surface‐Functionalized MXene for Enhanced Photocatalytic CO 2 Reduction

ABSTRACT MXenes have emerged as promising conductive and surface‐active materials for designing efficient photocatalytic systems for CO 2 ‐to‐hydrocarbon conversion, but their limited active sites and oxidation vulnerability remain major challenges. Herein, we report poly(catechol/p‐cresol) (PCA‐PCR) ligand‐functionalized MXene ( f ‐MXene) that exhibits enhanced oxidation stability under moisture‐involved conditions while largely preserving the electrical conductivity. The f ‐MXene is integrated with reduced TiO 2 (RT) semiconductor and copper (Cu) cocatalyst to construct a Cu/ f ‐MXene/RT ternary composite, which exhibits strong interfacial coupling and favorable band alignment, enabling efficient electron transfer from RT through f ‐MXene to Cu active sites. The optimized Cu/ f ‐MXene/RT catalyst achieves a CH 4 yield of 18.1 µmol g −1 , representing over 200‐fold enhancement compared to RT and more than double that of the Cu/MXene/RT. Synergistic interactions between Cu and f ‐MXene are essential, as neither component alone with RT achieves comparable activity. Moreover, the Cu/ f ‐MXene/RT catalyst also demonstrates superior cycling stability compared to the Cu/MXene/RT. Density functional theory (DFT) calculations indicate that the PCA‐PCR ligand suppresses excessive electron localization at Cu sites and promotes charge transfer to adsorbed CO 2 , facilitating its activation. This work demonstrates that ligand‐functionalized MXenes enable synergistic control over interfacial charge transport and structural stability, providing a robust strategy for designing advanced photocatalytic systems.