Facile assembly of Au nanoparticles modified hierarchical mesoporous In₂O₃ for highly sensitive ethanol gas detection

Flower-like In(OH)3 was synthesized by a facile homogeneous precipitation method and subsequently calcined at 300 degrees C to prepare nanosheets assembled 3D flower-like mesoporous In2O3, which was then modified with Au nanoparticles via sol-immobilization method to produce 3D hierarchical mesoporous Au/In2O3 for ethanol detection. The as-prepared Au/In2O3 were carefully characterized by XRD, SEM, HRTEM and XPS techniques. The flower-like structure was assembled by many ultrathin coarse mesoporous In2O3 nanosheets, and Au nanoparticles with an average size of 3.3 nm were evenly dispersed on In2O3 nanosheets. The 3D flower-like mesoporous 1%Au/In2O3 has a high specific surface area of about 130 m2 g-1 and shows the best sensitivity to ethanol among the flower-like mesoporous Au/In2O3 materials. It can sensitively detect ethanol gas at a relatively low temperature of 160 degrees C with a response of 115-50 ppm ethanol, increased by nearly 11 times compared to In2O3 at 210 degrees C. The 3D flower-like mesoporous 1%Au/In2O3 also has good selectivity to ethanol with response about 9.4, 26.1, 20.9 and 29.5 times higher than that to acetone, methanol, toluene and xylene, and it displays excellent linear relationship between the response and the ethanol concentration. The markedly improved sensitivity and selectivity of the 3D flower-like mesoporous 1%Au/In2O3 results from both the elec-tronic sensitization and chemical sensitization effects of Au nanoparticles. In short, the 3D flower-like meso-porous 1%Au/In2O3 possesses excellent sensitivity, selectivity, repeatability, linear relationship and long-term stability at 160 degrees C. Therefore, the obtained 3D flower-like mesoporous 1%Au/In2O3 has great potential for ethanol gas detection.