Polyphenol-Mediated Synthesis of Mesoporous Au–In₂O₃ Nanospheres 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.