Bi-doped urchin-like In2O3 hollow spheres: Synthesis and improved gas sensing and visible-light photocatalytic properties

Developing metal oxide semiconductor (MOS) based functional nanomaterials through designing novel nanostructure and doping with foreign element has attracted an increasing interest due to their promising applications in various fields including but not limited to gas sensor and photocatalysis. In this paper, we demonstrated a facile sovothermal-calcination route for synthesizing Bi-doped In2O3 urchin-like hollow spheres (ULHSs) and their upgraded gas sensing and visible-light photocatalytic performances. The successful doping Bi3+ into In2O3 crystal lattice was confirmed by various techniques. The results of gas sensing tests indicated that after doping In2O3 with Bi, an improved acetone sensitivity was achieved, especially in terms of higher response, faster response-recover speed and better selectivity. More importantly, the IBO-3 (the sample with an optimized molar ratio of Bi:In = 3:100) sensor also showed considerable humidity resistance and good response linearity within 0.3-5 ppm acetone, demonstrating its potential application in acetone sensor for monitoring exhaled breath. In addition, doping In2O3 with Bi also brought an improvement of visible-light photocatalytic performance. The reaction rate constant of IBO-3 for degrading methylene blue (MB) was about 4 times higher than that of the pure In2O3 counterpart.