Synthesis of vertical WO₃ nanoarrays with different morphologies using the same protocol for enhanced photocatalytic and photoelectrocatalytic performances

Abstract

Tungsten trioxide (WO₃) nanoarrays with different morphologies were successfully synthesized by a hydrothermal method on an FTO substrate. Various nanostructures of WO₃ 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 WO₃·0.33H₂O transformed to the monoclinic WO₃ phase under annealing at 500 °C. UV-Vis absorbance spectroscopy indicated that the absorption edge of WO₃ nanoflowers exhibited a slight red-shift compared to other morphologies of WO₃. The obtained WO₃ 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 WO₃ is discussed.