Abstract
An ultrasensitive methanol gas sensing device based on the quasi-molecular imprinting technology (quasi-MIT) is studied in this work. We applied the sol-gel method (ALS denotes Ag-LaFeO3 prepared by the sol-gel method) and combustion synthesis (ALC denotes Ag-LaFeO3 prepared by combustion synthesis) to prepare Ag-LaFeO3 based sensors. The morphologies and structures of the Ag-LaFeO3 materials were examined via various detection techniques. The ALSM and ALCM sensor (ALSM and ALCM denotes the devices prepared by coating the ALS and ALC materials with methanol, respectively) fabricated using the sol-gel method and combustion synthesis combined with quasi-MIT exhibit good gas sensing properties to methanol, in contrast with the two devices (ALSW and ALCW denote the devices prepared for coating the ALS and ALC materials with water, respectively) without the use of quasi-MIT. The results show that quasi-MIT introduced the target gas in the fabrication process of the device, playing an important role in the design of the ultrasensitive methanol gas sensor. The sensing response and the optimum working temperature of ALSM and ALCM gas sensor are 52.29 and 155 °C and 34.89 and 155 °C, respectively, for 5 ppm methanol, and the highest response to other gases is 8. The ALSM and ALCM gas sensors reveal good selectivity and response for methanol.
Highlights
Methanol is widely used in many fields such as pigments, pharmaceuticals and chemical products
We introduce the quasi molecular imprinting technique, which introduces the target gas into the process of material synthesis or device preparation to obtain a porous structure that is for the adsorption and desorption of methanol gas[17]
We designed the Ag-LaFeO3 for ultrasensitive methanol gas sensors based on the quasi-MIT
Summary
Gas-sensitive characteristics and related mechanisms of methanol gas detection by the ALSW, ALSM, ALCW and ALCM were carefully investigated. The enlarged image of the selected areas of the ALC and ALS samples (Fig. 3(d,i)) shows a porous structure with a micron-scale size. High-magnification TEM images of the ALC and ALS are shown in Fig. 4(b,f) and the clearly observed the lattice stripes indicate good crystallinity. The 530.5 eV peak of the OH XPS is attributed to the OH− resulting mainly from the chemically adsorbed water; this is due to lanthanum oxide, which can absorb moisture in the air This metal-support interaction is a major element in the analysis of the mechanism of gas sensor. Materials Na:ZnO nanoflowers Co3O4 nanosheets In2O3/SnO2 α-Fe2O3/Carbon nanotudes In2O3/ZnO NiO/ZnO In2O3/Al2O3 α-Fe2O3 Porous TiO2 Zn1−xCdxS ALSW ALSM ALCW ALCM
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