Enhanced formaldehyde gas-sensing response based on indium oxide nanowires doped with same-valence metal cations

Abstract

Mesoporous indium oxides nanowires (In₂O₃ NWs) doped with Al, Sb and La were synthesized using a nanocasting method, and then the components, microstructures and morphology were characterized. All results indicate that the doped metals are well dispersed in the In₂O₃ NWs and hardly affect the NW microstructure and morphology. While the cations-doped concentration decreases greatly with the increasing radii of Al, Sb and La cations. The cation-doping not only causes the lattice distortion to improve the adsorbed oxygen on the surface, but also increases the ground-state resistance of the In₂O₃ NWs. In this way, the cation-doping greatly affects the gas-sensing behavior of formaldehyde gas. Considering the resistance in air and formaldehyde gas, the In_1.984La_0.016O₃ NW sensor exhibits the best gas-sensing performance of 10 ppm formaldehyde gas with a response of 39.51 at 210 °C owing to the largest radius and lowest doping content of La³⁺.