Ultra-high ethanol sensitivity sensor based on porous In2O3 decorated with gold nanoparticles

Abstract

Reasonable adjustment of the morphology and surface modification with precious metals are effective methods to improve gas sensitive properties. In this work, the gold-loaded mesoporous In2O3 nanoparticles were successfully synthesized through facile hydrothermal reaction and surface in situ reduction reaction in the absence of templates and surfactants. Microstructure and morphological characteristics of obtained gold-loaded mesoporous In2O3 nanoparticles were characterized by XRD, XPS, SEM and TEM. The characterization results revealed that the particle size of obtained gold-loaded In2O3 samples are between 50 and 150 nm, and the specific surface area is 31.9 m2/g. Many mesopores formed on the surface, and the pore size is concentrated in 14 nm. Through systematic gas sensing tests, we found that due to the electron sensitization and chemical sensitization of gold nanoparticles, the activation energy of the reaction is effectively reduced, the diffusion of adsorbed oxygen is accelerated and the content of vacancy oxygen and chemisorbed oxygen is significantly increased. The results presented that sensors based on gold-loaded mesoporous In2O3 showed ultra-high sensitivity to 100 ppm ethanol at the temperature of 220 °C, which is far superior to pure In2O3 materials. Operating temperature, response and recovery time, selectivity and stability are also relatively better. It is expected for gold-loaded In2O3 to become an ideal material for ethanol detection in the field of gas sensors.