The orientation dependence of the photochemical reactivity of BiVO4

BiVO4 surfaces of all possible orientations have been used to photochemically reduce Ag+ and oxidize Pb2+. The surface orientations of grains, measured by electron backscatter diffraction, were correlated to the amounts of reduced and oxidized products on each surface. The results show that the photochemical reduction of Ag+ is strongly favored on BiVO4 (001) surfaces (indexed in group I2/b). However, Ag+ can be reduced on all orientations, with the rate of reduction decreasing with increasing inclination from the [001] direction. The oxidation of Pb2+ is strongly favored on (hk0) surfaces perpendicular to (001). Surfaces within 50 degrees of [001] have a much lower activity for the oxidation of Pb2+. The results also show that reduction and oxidation reactions occur on complementary surfaces of BiVO4 crystals.