Water-Mediated Photocatalytic Coproduction of Diesel Fuel Additives and Hydrogen from Dimethyl Ether

Dimethyl ether (DME) coupling via prior C–H bond scission affords H₂ and long-chain oxygenates that can be used as diesel fuel additives. However, the C–H bond of DME is recalcitrant, requiring activation by oxidants for subsequent C–C bond coupling, and overoxidation to CO₂ by nonselective oxidants is inevitable. Here, by establishing a channel for hole transfer from the Pt/TiO₂ photocatalyst to DME, the C–H bond of DME is broken, affording H₂ and diesel fuel additives consisting of glycol dimethyl ether (GDE) and oligomers. Adsorbed water on Pt/TiO₂ fosters hole transfer by forming hydrogen bonds with both Pt/TiO₂ surface and DME. Because of the hydrogen bonding, photogenerated holes are extracted from Pt/TiO₂ by water and eventually transferred to DME. As a result, the productivities of the diesel fuel and H₂ are increased by 8.7 and 12.4 folds, respectively. This work provides a route to produce two kinds of fuels from an abundant feedstock.