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• Simple synthesis of hollow Cu 2 O nanocages. • Low working temperature. • Good stability during 35 days. P-type metal oxide semiconductors with special morphology have received high expectation for their potential application in gas sensors. We have synthesized hollow dodecahedral Cu 2 O nanocages with exposed (1 1 1) planes by a simple solution growth approach at room temperature. Characterization results indicate that the diameters of Cu 2 O nanocages are about 200 nm. Gas sensing performance of the Cu 2 O nanocages is investigated towards ethanol gas. Remarkably, the response of Cu 2 O reaches 4.6 at a low working temperature of 250 °C when the concentration is 100 ppm. The unique structure of Cu 2 O benefits the sensing performance owing to its active (1 1 1) planes. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The methanol gas sensing property of the nitrogen-doped quantum dot/Ag-LaFeO 3 p-n heterojunction materials (NALPN) are advanced and the experimental findings are innovative. • The response of NALPN sensor to 5 ppm methanol is 73 and the maximum response to other gases is 5 at 92°C. • The gas sensitivity test results show NALPN is a good gas-sensitive material with high response, low operating temperature and good selectivity to 5 ppm methanol gas. Abstract The unique electronic properties (electron mobility and carrier lifetime) are key factors for metal oxide semiconductor devices that directly determine the device's performance and application. Electron mobility of metal oxide semiconductor has a certain impact on response and operating temperature of gas sensor. Heterojunction composites of carbon quantum dots (CQDs) and perovskite materials have attracted much attention due to their great potential for gas sensors. In this paper, a gas sensor for monitoring methanol gas was developed based on nitrogen-doped carbon quantum dot/Ag-LaFeO 3 (NCQDs/Ag-LaFeO 3) p-n heterojunction materials (NALPN). NCQDS and Ag-LaFeO 3 form a heterojunction, which improves the carrier transport ability and separation of electron-hole pairs. The surface of NCQDs contains COOH, optimize the selectivity of Ag-LaFeO 3 to methanol gas. Gas sensitivity test results show that the NALPN to 5 ppm methanol gas possessed high response (73), low operating temperature (92 °C) and good selectivity. These excellent properties prove that NALPN materials are the main competitors for future gas sensitive materials. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Excellent sensitivity and selectivity have been achieved. • The working temperature of the toluene gas sensor is relatively low. • The sensor shows good long-term stability. • Gas-sensing properties of Ag-LaFeO 3 are enhanced by microwave radiation and molecular imprinting technology. Abstract Highly sensitive and selective detection against toluene gas remains a tremendous challenge in gas sensor applications. In this work, a series of molecular imprinted Ag-LaFeO 3 nanoparticles (IAL NPs) were synthesized in a microwave-assisted colloidal route. Especially, the one prepared with optimal amount of imprint molecules (IAL-2 NPs) have a response of 24.0 to 5 ppm toluene at the optimum working temperature of 215 °C with negligible responses to the other test gases, exhibiting enhanced gas sensing properties for toluene gas at a relatively low working temperature. The improved performance can be attributed to the favorable effect of microwave radiation, the molecular imprinting structure and the sensitization of Ag, which illuminates that IAL-2 NPs is a potential candidate for toluene detection. [ABSTRACT FROM AUTHOR]