Effects of Fe3+-doping and nano-TiO2/WO3 decoration on the ultraviolet absorption and gas-sensing properties of ZnSnO3 solid particles

Zn1-xFexSnO3+x/2 samples (ZFxSO), composed of quasi-spherical solid particles, were synthesized after the calcination of Zn1-xFexSn(OH)6+x and then decorated by nano-TiO2/WO3. The ethanol sensitive performance of pure ZnSnO3 sample can be enhanced by Fe3+-doping at high temperature. The ZF0.1SO sample (i.e., x = 0.1) exhibits highest gas sensing response to ethanol among the ZFxSO samples at 500 ppm, obtaining a maximum response (Rmax) of 260.8 at 260 °C. Although Fe3+-doping can increase the oxygen vacancies in pure ZnSnO3 sample, it can not significantly change the ultraviolet absorption spectrum of the sample due to its strong electronegativity. However, nano-TiO2/WO3 decoration can broaden the ultraviolet absorption spectrum of ZF0.1SO sample and improve its absorption intensity. Under 385 nm UV illumination, the operating temperature (OT) of ZF0.1SO sensor can be reduced by nano-TiO2 decoration, with a Rmax of 198.7 at 110 °C. Moreover, the OT of the ZF0.1SO sensor can be further reduced by the co-decoration of nano-TiO2 and WO3, with a Rmax of 219.5 at 100 °C under the same testing conditions. Possible reasons on the role of Fe3+-doping and nano-TiO2/WO3 decoration were discussed from material structure.