Nanoscale Ag-decorated CuO/SnO2 heterojunctions with coralloid hollow porous structure (ACSO HPs) were successfully synthesized though a hydrothermal route with electroless Ag plating followed by the calcination and acid-washing. Detailed microstructural characterizations confirmed that the hollow porous structure comprised CuO/SnO2 and Ag/SnO2 nanoheterojunctions, and the SnO2 surface was decorated primarily with nano-Ag, which was the outer layer of the structure. The ACSO HPs sensor displayed a higher response to isopropanol compared to toluene, acetone, benzene, ethanol, and methanol than other samples. For 100 ppm isopropanol, the ACSO sensor exhibited a faster response time (6 s) and a higher recovery time (34 s) than undecorated Ag samples. The improved sensing performance of ACSO samples was ascribed to the synergistic effect of the CuO/SnO2 nanoheterojunctions with the dramatic sensitization of the decorated nano-Ag, as well as the HPs.
The design of a sensing material for detecting isopropanol gas with low operating temperature is extremely important for miniaturization and wearability of gas sensors. Herein, a novel gas sensor based on SnO 2 -Carbon nanosphere heterojunctions decorated with Ag nanoparticles (SCA) was fabricated and its gas sensing performance was evaluated and compared systematically. The measurement results indicated that the sensing performance was influenced by the ratio of Sn/C and the length of Ag plating, and the SCA sensor provided the best response. For 100 ppm isopropanol at 100 °C, the SCA sensor exhibited a response value of 50.51, a response time of 7 s and a recovery time of 60 s. The enhanced sensing performance and reduced operating temperature of the SCA could be attributed to the synergistic effect of the SnO 2 -Carbon nanosphere heterojunctions and the significant catalytic performance of the decorated Ag nanoparticles. In addition, the density functional theory calculation method based on the first-principles theory was used to study the adsorption performance and electronic behavior, as well as the influence of Ag decoration on SnO 2 for isopropanol detection. The calculated results were consistent with the experimental results.
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