A New WO3/FeVO4Nanostructured Heterojunction for Solar-driven Water Oxidation

Abstract

We report the first application of a nanostructured WO3/FeVO4 heterojunction to photoelectrochemical (PEC) water oxidation. The heterojunction films were prepared by drop-casting a low bandgap (∼2.1 eV) FeVO4 layer onto a wider bandgap (∼2.8 eV) WO3 nanoporous film supported on a fluorine-doped tin oxide coated glass substrate. The structural, optical and PEC properties of the prepared heterojunction were analysed in detail, and it was found that the WO3/FeVO4 composite reached maximum photocurrent densities under simulated sunlight up to 3.3 and 12 times higher than those of pristine WO3 and FeVO4 photoanodes, respectively. A large and desirable ∼400 mV cathodic shift in the photocurrent onset potential relative to pristine FeVO4 was also observed, which can be attributed to lower surface recombination and more efficient bulk separation of photogenerated electron-hole pairs compared with both pristine FeVO4 and WO3. These findings suggest that WO3/FeVO4 nanostructured heterojunctions may find applications in solar-driven water splitting cells.