Photoelectrochemical properties of TiO2 rutile microalloyed with 4d and 5d transition elements

The microalloying effects of 4d and 5d transition metals on the photoelectrochemical properties of rutile titanium oxide are investigated by a series of experiments and DV-Xα molecular orbital calculation. Rutile TiO2 and (Ti, M)O2 oxides (M: Nb, Mo, Ta, W) can be made by the oxidation of pure Ti and Ti–5 mol% M alloys, respectively. The saturated photocurrent density of rutile (Ti, M)O2 is dependent on the additional element, M, and it lowers in the order, Nb>Ta>Mo>W. The visible light response at 620 nm in rutile (Ti, Ta)O2 and at 620 and 730 nm in rutile (Ti,W)O2 is found by measuring the spectral dependence of anodic photocurrent density at 1000 mV vs. SCE. The experimental results can be explained by the calculated level structures of the microalloyed rutile oxides.