Nanostructured WO3 films using high temperature anodization

Abstract We have investigated the formation of highly porous nanostructured tungsten trioxide (WO 3 ) films of several microns thickness using elevated temperature anodization in nitric acid. Plate-like crystals with thicknesses in the range of 20–60 nm and lengths in the order of 50–1000 nm were obtained after anodization of tungsten foil in 1.5 M HNO 3 at 50 °C. High intensity {2 0 0} WO 3 crystallographic signatures from platelets revealed the presence of predominantly orthorhombic WO 3 nanoplatelets in annealed (up to 550 °C) samples. Photocurrent measurements revealed that 4 h anodized sample at 20 V produced the largest photocurrent density. High photocurrent response from the nanoplateleted films show the possibility of developing efficient WO 3 /electrolyte sandwiched photosensors.