Ag Nanoparticle-Modified ZnO–In2O3 Nanocomposites for Low-Temperature Rapid Detection Hydrogen Gas Sensors

Current semiconductor gas sensors still have significant limitations in achieving rapid measurement of hydrogen at lower operating temperatures. Therefore, in this article, ZnO–In2O3 sensors modified with noble metal Ag are designed by constructing a heterojunction and combining it with noble metal modification for the rapid detection of hydrogen at low (working) temperatures. In this article, hydrogen gas sensors based on ZnO multilayer nanosheets and In2O3 nanoparticle (NP) composites were first synthesized through a one-step hydrothermal route. Then, on top of this, the loading of Ag NPs was successfully achieved by the chemical reduction method, and finally, the hydrogen gas sensors based on ZnO–In2O3 ternary nanocomposite modified with Ag NPs were prepared. The physicochemical features of the gas-sensitive substances were described by various characterization techniques. The sensing performance of ZnO, ZnO–In2O3, and Ag-modified ZnO–In2O3 sensors was systematically tested. The test results manifest that the Ag NPs-loaded ZnO–In2O3 sensor responds up to 103.75 to 100-ppm H2 at an inferior temperature of 160 °C with the response/recovery times of 1.6 and 47.8 s, respectively, and the lowest detectable gas concentration of 2 ppm. In addition, the gas-sensitive element exhibits favorable repeatability, stability, and excellent selectivity. Based on the experimental test results and characterization data resolution, the improved inductive capability of the sensors is chiefly attributed to the expansion of the specific surface area of the gas-sensitive material (39.8412 m2/g), the constitution of the heterojunction interface, and the cooperation of chemical and electronic sensitization of noble metal Ag.