Dynamic interfacial proton-electron synchronization on MOF-derived Ag2O/TiO2 heterojunctions for steering CO2 photoreduction to methane

MOF-derived Ag 2 O/TiO 2 p-n heterojunction enhances charge separation. • Ag 2 O acts as a proton shuttle, enabling selective CO 2 reduction to CH 4 . • In-situ DRIFTS and DFT reveal the key role of *CO protonation. • Achieves 27.89 μmol g −1 h −1 CH 4 rate with 85.87% selectivity. The photocatalytic conversion efficiency of CO 2 with H 2 O to hydrocarbons is dependent on the simultaneous enrichment of protons and electrons. Herein, the composite photocatalyst of Ag 2 O/TiO 2 were constructed by anchoring Ag 2 O species onto the MOF-derived TiO 2 support via a laser deposition technique. The optimally engineered Ag 2 O/TiO 2 photocatalyst exhibited a remarkable CH 4 selectivity of 85.87% with a formation rate of 27.89 μmol g −1 h −1 in the photocatalytic reduction of CO 2 to CH 4 , surpassing the near-zero CH 4 yield of pristine MIL-125(Ti). By combining the results of in situ DRIFT spectra and density functional theory calculations, the photocatalytic mechanism is proposed: The catalytic interface effectively overcomes the kinetic bottleneck of *CO hydrogenation, by synchronously delivering enriched protons from the Ag 2 O sites and photogenerated electrons from the MOF-derived TiO 2 support. This targeted facilitation of the critical *CO protonation step suppresses intermediate desorption which dictates the selectivity toward CH 4 . This work unveils a universal strategy of coupling robust MOF-derived microenvironments with dynamic proton-electron delivery to overcome kinetic limitations in multi-step catalytic processes. Download: Download high-res image (277KB) Download: Download full-size image