Hollow mesoporous In2O3 derived from MIL-68 (In) for dual gas sensing of NO2 and H2
NO 2 is one of the most important air pollutant gases for the environment and human health. H 2 is seen as the next generation of clean energy to promote sustainable development. However, sensitive detection of NO 2 at room temperature is still a major challenge, and reliable H 2 sensors are also scarce. Metal oxide semiconductor (MOS) gas sensors are advantageous for detecting gas. Hence, we synthesized the unique hexahedral hollow mesoporous In 2 O 3 (h-In 2 O 3 ) derived from MIL-68 (In). The formation process and properties of h-In 2 O 3 were analyzed. The surface of h-In 2 O 3 is rich in hydroxyl groups , which are active sites for NO 2 adsorption at room temperature. Increasing working temperature up to 160 °C enables effective sensing reaction with H 2 . Based on different temperature-dependent gas sensing mechanisms, the h-In 2 O 3 sensor exhibits ultrasensitive response values of 400 towards 100 ppb NO 2 at room temperature (24 °C) and of 17.99 towards 10 ppm H 2 at 160 °C. In addition, the h-In 2 O 3 sensor exhibits reliable linear response, low theoretical detection limit of 1.8 ppt and 23 ppb for NO 2 and H 2 , excellent selectivity, repeatability and long-term stability. The synergistic effect of the unique structure, larger specific surface area , and abundant adsorbed oxygen plus oxygen vacancy contribute to the excellent gas sensing performance of the h-In 2 O 3 sensor. This study provides a promising strategy for the development of bifunctional gas sensors.
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