Porous In2O3:RE (RE = Gd, Tb, Dy, Ho, Er, Tm, Yb) Nanotubes: Electrospinning Preparation and Room Gas-Sensing Properties

In2O3:RE (RE = Gd, Tb, Dy, Ho, Er, Tm, Yb) as well as In2O3 nanotubes (NTs) with a diameter of similar to 85 nm and wall thickness of similar to 15 nm were systematically fabricated by the electrospinning method for the first time and characterized by various techniques. The results demonstrate that, except for In2O3:Tb, which contained a mixed phase (cubic and rhombohedral), the lattice constants of cubic In2O3:RE gradually decreased and the band-gap energies and the resistances in air gradually increased with the increase of doped RE atom order. As a consequence, it is exciting to observe that the doping of RE gradually and significantly improved the gas-sensing properties of In2O3 NTs to H2S gas as the RE varied from Gd to Yb in order. In contrast to undoped In2O3 NTs, the room-temperature response sensitivity of the In2O3:Yb NT sensors to 20 ppm H2S increased about 7 times and reached as high as 1241, whereas the response time of the In2O3:Yb NT sensors was shortened 4 times and reached similar to 49 s. The present electrospun In2O3:RE NTs are highly promising H2S gas sensors that can work under soft conditions.