We report on a novel heterojunction WO(3)/BiVO(4) photoanode for photoelectrochemical water splitting. The heterojunction films are prepared by solvothermal deposition of a WO(3) nanorod-array film onto fluorine-doped tin oxide (FTO) coated glass, with subsequent deposition of a low bandgap, 2.4 eV, visible light responding BiVO(4) layer by spin-coating. The heterojunction structure offers enhanced photoconversion efficiency and increased photocorrosion stability. Compared to planar WO(3)/BiVO(4) heterojunction films, the nanorod-array films show significantly improved photoelectrochemical properties due, we believe, to the high surface area and improved separation of the photogenerated charge at the WO(3)/BiVO(4) interface. Synthesis details are discussed, with film morphologies and structures characterized by field emission scanning electron microscopy and X-ray diffraction.

Photocorrosion stable WO(3) nanowire arrays are synthesized by a solvothermal technique on fluorine-doped tin oxide coated glass. WO(3) morphologies of hexagonal and monoclinic structure, ranging from nanowire to nanoflake arrays, are tailored by adjusting solution composition with growth along the (001) direction. Photoelectrochemical measurements of illustrative films show incident photon-to-current conversion efficiencies higher than 60% at 400 nm with a photocurrent of 1.43 mA/cm(2) under AM 1.5G illumination. Our solvothermal film growth technique offers an exciting opportunity for growth of one-dimensional metal oxide nanostructures with practical application in photoelectrochemical energy conversion.

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