Synthesis of Sb doping hierarchical WO3 microspheres and mechanism of enhancing sensing properties to NO2

Sb-doped tungsten oxides have been synthesized successfully by a hydrothermal method without any surfactant at 120 °C for 24 h. The structure and morphology of product were examined by XRD and SEM. The sensing tests reveal that the enhancement to NO2 response by Sb doping is very significant compared to that reported in literatures. Especially, the highest response of 3.5 wt%-Sb doped WO3 exhibits 9 times higher than that of undoped sample. The transient responses of the sample to different concentrations of NO2 were also measured and modeled using L–H heterogeneous reaction mechanism. The mechanism of enhancing sensing performance is also discussed in detail, which attributed to the changes of material intrinsic defects and binding energies and has been confirmed by the room temperature PL and XPS spectra. The first-principle calculations indicate that the dopant as acceptor enter into tungsten oxide resulting in reduce in free electron concentration of system, which is in good agreement with the increase in resistance obtained from experiment measurements. Sb-doped tungsten oxides have been synthesized successfully by hydrothermal method without any surfactant at 120 °C for 24 h, which not only exhibists high response to NO2, good selectivity to ethanol, acetone, NH3, methanol and CO, but also exhibits good linear responses in the concentration range of 1 ppm to 8 ppm. [Display omitted] •Sb-doped hierarchical WO3 was synthesized with the assistance of citric acid.•Sensitivity of WO3 to 8 ppm NO2 at 125 °C is enhanced 9 times by doping 3.5 wt% Sb.•Response time is shortened disproportionately with increasing gas concentration.•The enhanced sensing is attributed to the change of defect and binding energy.•First principle calculations reveal the bandgap of WO3 is widened after Sb doping.