Nanostructured WO3 films using high temperature anodization

We have investigated the formation of highly porous nanostructured tungsten trioxide (WO3) 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 HNO3 at 50 °C. High intensity {2 0 0} WO3 crystallographic signatures from platelets revealed the presence of predominantly orthorhombic WO3 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 WO3/electrolyte sandwiched photosensors.