Ni/Au bimetal decorated In2O3 nanotubes for ultra-sensitive ethanol detection

Abstract In this work, we report on a high-performance ethanol sensor using Au decorated Ni-doped In2O3 nanotubes (NIO-Au NTs). The morphology, microstructure and surface chemistry of pristine In2O3, NIO and NIO-Au NTs have been discussed by the analysis of SEM, TEM, XRD and XPS spectra. Gas sensing test results reveal that NIO-Au NTs with optimal Au decorated concentration of 2 mol% (NIO-2 mol% Au) exhibits the highest response of 167 towards 50 ppm ethanol at lower working temperature (180 °C), which is about 18 times and 13 times higher than pristine In2O3 NTs and Ni-doped In2O3 NTs, respectively. Moreover, some other important gas sensing properties of NIO-2 mol% Au NTs, such as selectivity and stability, have been proved to be greatly improved. The approach and results proposed in this study are attributed to the catalysis of Ni, the spillover effect of Au and formation of Schottky barrier. The proposed functional hybrid nanomaterial-based sensing strategy offers an effective design for highly sensitive and efficient VOC detection devices, which can operate well at low temperatures also.