Enhancement of MTBE photocatalytic degradation by modification of TiO2 with gold nanoparticles

The photocatalytic degradation of methyl tert-butyl ether by gold-modified TiO2 has been studied by a combination of high resolution electron microscopy, X-ray photoelectron spectroscopy and reactor measurements. The optimum gold loading corresponded to a mean Au particle size of ⩽ 3 nm at which point the gold may no longer be metallic. Such catalysts exhibited a threefold rate enhancement compared to unmodified TiO2, possibly due to injection of photo-excited electrons from semiconducting Au into the TiO2 conduction band. Since the presence of dissolved oxygen was crucially important to good performance, it is possible that an additional factor was lowering of the local work function, thus promoting electron transfer to dioxygen molecules adsorbed at the Au/TiO2 interface.