Structural and alcohol response characteristics of Sn-doped WO3 nanosheets

Sn-doped WO3 materials were synthesized by chemical co-precipitation route using sodium tungstate dihydrate (Na2WO4·2H2O) as the host precursor and stannic tetrachloride hydrated (SnCl4·5H2O) as the source of Sn dopant. X-ray diffraction (XRD) analyses confirm that the prepared materials are polycrystalline WO3, possessing monoclinic structure with crystallite sizes in the range 22–44nm. The transmission electron microscopy (TEM) images of the samples show a sheet-like morphology embedded with small nanosized crystallites. The energy dispersive X-ray (EDX) analyses of the samples confirm incorporation of Sn ions into WO3 lattice network. The alcohol response characteristics of the samples were studied by measuring the change in its electrical resistance before and after exposure to test alcohol vapours at different operating temperatures (150–250°C) for various concentrations (10–50ppm) in air. On Sn doping, the response has been found to increase for all the test alcohols. It has been observed that at each operating temperature and concentration under investigation, the response to propan-2-ol is maximum, followed by those to ethanol and methanol. On Sn doping, the response and recovery times for all the test alcohols have been found to decrease relative to those observed in the case of undoped WO3 nanosheets.