Synthesis of vertical WO nanoarrays with different morphologies using the same protocol for enhanced photocatalytic and photoelectrocatalytic performances.

Tungsten trioxide (WO) nanoarrays with different morphologies were successfully synthesized by a hydrothermal method on an FTO substrate. Various nanostructures of WO including nanoflakes, nanoplates, nanoflowers and nanorods were obtained by adjusting only the acidity of the precursor solution. XRD patterns confirmed that the as-prepared orthorhombic WO·0.33HO transformed to the monoclinic WO phase under annealing at 500 °C. UV-Vis absorbance spectroscopy indicated that the absorption edge of WO nanoflowers exhibited a slight red-shift compared to other morphologies of WO. The obtained WO nanoflower arrays exhibit the highest photocurrent density and photocatalytic degradation activity towards methylene blue. Finally, the mechanism of the photocatalytic degradation of methylene blue by WO is discussed.