Fabrication of bismuth copper vanadate electrodes through feasible chemical solution method for visible light-induced water oxidation

Film electrodes of a ternary metal oxide, bismuth copper vanadate (BiCu2VO6), were fabricated directly on FTO (fluorine-doped tin oxide glass) substrates by a chemical solution method using precursor solution of the component metal ions. To improve the purity of BiCu2VO6 films, temperature and time in pre-heating process were carefully selected by thermogravimetric and differential thermal analysis and X-ray photoelectron spectroscopy of the precursor film. The fabrication of pure BiCu2VO6 films keeping tight contact to the FTO substrate was confirmed by X-ray diffraction, cross-sectional scanning electron microscope images, and scratching the film using a soft paper. The band gap energy E (g) = 2.10 V and the flat band potential U (FB) = 0.43 V (vs. SHE at pH 0) for BiCu2VO6 were obtained. For the photoelectrode, wavelength dependence of the incident photon to current efficiency (IPCE) corresponded to the absorption spectrum, and the IPCE exhibited several-folds larger values than those of the electrode fabricated by depositing BiCu2VO6 particles on an FTO substrate.