Mesoporous Zn2SnO4 for efficient sensing of ethylene glycol vapor

Within this study, mesoporous Zn2SnO4 nanostructures have been prepared by a facile and eco-friendly hydrothermal method. Through X-ray diffraction analysis, a polycrystalline zinc tin oxide structure is recognized with a cubic inverse spinel phase crystal structure. By Field emission scanning electron microscopy method, various morphologies based on the hydrothermal time ranging from the cubic-like morphology, irregular hexagonal plates, and large quantity of microspheres to the truncated octahedron have been observed. By the aid of Energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy analyses, the atomic ratio and characteristic vibration peaks of Zn2SnO4 have been evaluated. By the help of Brunauer–Emmett–Teller analysis, specific surface area, mean pore diameter, and total pore volume were measured. The nanostructured Zn2SnO4 prepared in 36 h hydrothermal treatment (as a selected sample) showed a higher BET specific surface area (9.10 m2/g) and total pore volume (0.078 cm3/g) than the other samples. The gas-sensing performance of the samples was investigated towards different vapors. The optimum operating temperature (270 °C), transient response, response/recovery times, and long-term stability (eight months) of the samples have been evaluated. For the selected sample, appreciable sensing response (92.92 toward 100 ppm ethylene glycol), the ultra-fast response time (1 s), excellent selectivity (about 6–23 times more than other tested vapors) and excellent long-term stability (the response decay of about 10% after eight months) has been perceived which makes it a promising gas sensor. It seems that the selected sample has shown relatively better performance for two reasons: Firstly, high crystalline quality (largest crystallite size and lowest strain value) which can affect the combination or separation of adsorbed oxygen species on the surface of the material. Secondly, the higher specific surface area and the relatively larger total pore volume can lead to more gas adsorption sites leading to further narrowing of the depletion layer and resulting in a high and very fast response.