Coupling photocatalytic CO₂ reduction and CH₃OH oxidation for selective dimethoxymethane production

Currently, conventional dimethoxymethane synthesis methods are environmentally unfriendly. Here, we report a photo-redox catalysis system to generate dimethoxymethane using a silver and tungsten co-modified blue titanium dioxide catalyst (Ag.W-BTO) by coupling CO₂ reduction and CH₃OH oxidation under mild conditions. The Ag.W-BTO structure and its electron and hole transfer are comprehensively investigated by combining advanced characterizations and theoretical studies. Strikingly, Ag.W-BTO achieve a record photocatalytic activity of 5702.49 µmol g⁻¹ with 92.08% dimethoxymethane selectivity in 9 h of ultraviolet-visible irradiation without sacrificial agents. Systematic isotope labeling experiments, in-situ diffuse reflectance infrared Fourier-transform analysis, and theoretical calculations reveal that the Ag and W species respectively catalyze CO₂ conversion to *CH₂O and CH₃OH oxidation to *CH₃O. Subsequently, an asymmetric carbon-oxygen coupling process between these two crucial intermediates produces dimethoxymethane. This work presents a CO₂ photocatalytic reduction system for multi-carbon production to meet the objectives of sustainable economic development and carbon neutrality.