Facile synthesis and gas-sensing performance of Sr- or Fe-doped In2O3 hollow sub-microspheres

Sr- or Fe-doped In2O3 hollow sub-microspheres were successfully fabricated without the assistance of any additives or templates. The obtained hollow In2O3 sub-microspheres show relatively uniform size and band gap of similar to 3.1 eV. Benefited from the hollow microstructure and doping effect, the doped In2O3 sub-microspheres show excellent gas sensing performance towards a series of organic solvents. For 100 ppm of formaldehyde, the Sr-and Fe-doped In2O3 sensors demonstrate sensing responses of 9.4 and 5.5, respectively. These values are much higher than previously reported In2O3-based gas sensors. Interestingly, Fe-doped In2O3 shows relatively higher sensing response to propanol than that of Sr-doped In2O3, although towards formaldehyde, ethanol, acetone and heptane, Sr-doped In2O3 shows relatively higher sensing responses. This investigation therefore indicates that doped In2O3 hollow microstructures could be an effective platform for sensing hazardous indoor formaldehyde gas, and that sensing selectivity could be improved through the doping effect.