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.