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

Abstract

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 ∼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.