Fabrication of WO3 nanoflakes by a dealloying-based approach

We demonstrate the fabrication of WO3 nanoflakes by dealloying with subsequent thermal oxidation. Sputtered amorphous W0.68Cu0.32 alloy films were dealloyed in HNO3 solution where Cu was selectively removed and W self-assembled into crosslinked cubic phase W nanoflakes. This kind of W nanoflakes was transformed to monoclinic WO3 nanoflakes by thermal oxidation at 500 degrees C. Gas sensor made using the WO3 nanoflakes showed promising NO2-sensing performance.