Highly sensitive ethanol sensor based on Ag NP-modified SnO2–In2Sn2O7-x ternary composite enhanced by synergistic catalysis

Abstract

In this paper, the noble metal Ag-modified SnO2–In2Sn2O7-x ternary nanocomposites were designed to detect ethanol efficiently. Firstly, the SnO2–In2Sn2O7-x nanocomposites were synthesized by a simple hydrothermal method, and the microstructure of the SnO2 nanomaterials were adjusted by controlling the content of In2Sn2O7-x. With the increase of In2Sn2O7-x content, the morphology of the synthesized SnO2–In2Sn2O7-x composites gradually tends to be regular with porous spherical morphology. In the same synthesis conditions, the porous spherical morphology of SnO2–In2Sn2O7-x composites was more uniform at 0.5 at% of In element content, and the distribution in the material was more homogeneous and dispersed, which was conducive to the diffusion and adsorption of gases on the surface of the material, as well as to the loading of Ag nanoparticles. On this basis, the Ag nanoparticles were successfully modified through the chemical reduction route, and the Ag nanoparticles modified SnO2–In2Sn2O7-x with 0.5 at% In elemental content ternary nanocomposites were prepared. X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Energy Dispersive Spectrometer (EDS) were used to characterize the structure and morphology of the prepared gas-sensitive materials. The gas-sensing performance of SnO2, In2Sn2O7-x, SnO2–In2Sn2O7-x, and Ag-modified SnO2–In2Sn2O7-x sensors were tested systematically. The results showed that the 1.5 wt% Ag-modified SnO2–In2Sn2O7-x nanocomposites with 0.5 at% In elemental content have good gas-sensing properties. The response of the sensor to 100 ppm ethanol vapor can reach 666 at the optimal operating temperature of 250 °C, and the response time is shortened to 45 s. It has good sensitivity for ethanol gas, and the minimum detectable gas concentration is reduced to 500 ppb. The improved performance of the sensor is primarily due to the construction of the heterogeneous interface of the SnO2 and In2Sn2O7-x and the catalytic synergism of the noble metal Ag.