Photocatalytic methanol reforming on Au/TiO2 for hydrogen production

Methanol can be reformed with water, at ambient temperature, using photocatalysis, and this reaction represents a possible low energy, more sustainable pathway to hydrogen production than (for instance) steam reforming. The requirements for the catalysts are rather strict since titania itself is almost inactive for anaerobic photocatalysis, whereas the addition of a very limited range of metals to the surface renders it active. Surprisingly, this includes gold, which shows one of the highest reactivities for hydrogen production. The mechanism is proposed to involve the methoxy and formate intermediates, the latter being implicated in the route to CO2 and hydrogen production. One oxygen atom is supplied from the titania support, which is replaced in the catalytic cycle by oxygen from water. The threshold for the excitation is that for bandgap excitation into the titania conduction band, which stores the energy for reactivation, and this is mediated by electrophilic oxygen.