Hydroxyl-Mediated CH 4 Activation Boosting Heterogeneous Coupling on Ti-Cu Dual Sites in Photocatalytic Co-Conversion of CH 4 and CO 2

Photocatalytic co-conversion of CH4 and CO2 for synthesizing C2+ chemicals represents an environmentally friendly strategy for advancing carbon neutrality and reducing the greenhouse effect. However, several critical challenges remain, especially the difficulties in methane activation and heterogeneous coupling between CH4-derived and CO2-derived intermediates. Herein, we report a Cu-incorporated TiO2-SiO2 (Cu-TS) photocatalyst capable of achieving heterogeneous coupling between *CO and *CH3 intermediates, respectively, derived from CO2 and CH4. The optimized system demonstrates a C2 selectivity of 52% and a total C2 hydrocarbon production rate of 18 ± 2 μmol g−1 h−1, comprising 16 ± 1 μmol g−1 h−1 of C2H6 and 2 ± 1 μmol g−1 h−1 of C2H4 under 365 nm irradiation at ambient conditions, which is approximately 6.8 and 34.2 times those on pure TiO2-SiO2 (TS) and on Cu-TiO2, respectively. Mechanistic investigations indicate that CH4 preferentially interacts with ·OH radicals generated from Si-OH groups, forming the key intermediate *CH3 adsorbed on the Ti sites. Cu nanoparticles serve as active sites for CO2 adsorption and reduction to form the *CO intermediate. Subsequently, these two intermediates heterogeneously couple with each other at adjacent Cu and Ti sites to yield C2 hydrocarbons. This study realizes ·OH-mediated CH4 activation on CH4 and CO2 co-conversion and achieves the heterogeneous C−C coupling between *CO and *CH3 intermediates on adjacent dual-metal sites, establishing a strategy for designing multi-site synergistic photocatalysts targeting C2 production under mild conditions.