Fabrication and Properties of a Branched (NH₄)_xWO₃ Nanowire Array Film and a Porous WO₃ Nanorod Array Film

We describe the successful fabrication of a three-dimensional branched (NH₄)_xWO₃ nanowire array film on fluorine-doped tin oxide coated glass by a facile one-step hydrothermal method. The porous WO₃ nanorod array film formed after heat treatment and recrystallization. Specifically, the branched (NH₄)_xWO₃ nanowire array film has very thin nanowires that were about 10 nm in diameter. The results of an optical and photoelectrochemical test show that the branched (NH₄)_xWO₃ nanowire array film could be used as a near-infrared shielder, while the porous WO₃ nanorod array film can be used as a photoanode for water splitting. Moreover, the morphology, structure, and composition of the as-prepared films are revealed, and the related changes caused by heat treatment are discussed in detail.