Ag-Modified Co3O4-In2O3 Nanohollow Microspheres for H2 Detection

The gas-sensitive original requires low operating temperature, low detection limit, and fast response speed for hydrogen detection. In this article, sensors of Ag-Co3O4-In2O3 ternary composites with hollow microsphere structures were prepared by a one-step hydrothermal process by constructing p-n heterojunction and modifying it with noble metal Ag for the realization of rapid hydrogen detection. The gas-sensitive performance of the sensor is analyzed and tested by characterization techniques and systematic testing. The 2 wt% Ag-0.5 at% Co3O4-In2O3 has the best performance, with an optimal operating temperature of
$160~^{\circ }$
C, a response value of 23.55 for hydrogen (100 ppm), a response/recovery time of 6/213 s, and a lower limit of detection of 2 ppm. Compared with the pure In2O3 sensor, due to the formation of heterojunction and the synergistic catalytic effect of noble metal, the response value is improved by
$2.4\times $
, and
$60~^{\circ }$
C lowers the working temperature. Meanwhile, the sensor has excellent selectivity, stability, and repeatability. Finally, the sensitization mechanism of the sensor is discussed according to the test results and characterization analysis.