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

Dimethyl ether (DME) coupling via prior C-H bond scission affords H-2 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 H-2 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 H-2 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.