Polyphenol-Mediated Synthesis of Mesoporous Au-In₂O₃Nanospheres for Room-Temperature Detection of Triethylamine

Semiconductor metal oxide gas sensors have been frequently used for gas monitoring and detection in different applications. However, the working temperature is usually high (>150 °C), which requires an additional heater and results in high energy consumption and low stability. Herein, mesoporous Au-In2O3 spheres are prepared by direct thermal decomposition of metal-polyphenol hybrids and applied for room-temperature detection of triethylamine vapor. Plant polyphenols are used as a "molecular glue"to interact with Au and In species and mediate the synthesis process. After chemical cross-linking with formaldehyde, spherical gold-indium-polyphenol hybrids are prepared. Mesoporous Au-In2O3 spheres can be prepared by calcination in air. The obtained spheres show high specific surface area (56.8 m2/g), large pore size (∼5.8 nm), and uniform spherical morphology (∼100 nm). Mesoporous Au-In2O3 spheres show high response (54.9) toward 10 ppm of triethylamine vapor at room temperature (25 °C). The modification of Au species on the mesoporous In2O3 spheres can obviously decrease the working temperature from 200 to 25 °C and significantly increase the response toward TEA (about 9.6-fold) compared with pure mesoporous In2O3 spheres. In comparison with the traditional post-modification strategy, the one-pot modification method can further improve the sensing performance of mesoporous In2O3 spheres. This work provides a feasible synthesis strategy to prepare mesoporous noble metal-In2O3 hybrid spheres, which could be used for fabrication of the gas sensor with low energy consumption and high sensitivity.