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The multiple edge sites on 2D nanosheets or nanoplates usually supply more active sites which result in the enhancement of gas sensing performance. Manufacturing porous structure, with high density of edge sites coupled under the irradiation of UV light, have great potential in NO2 gas selectivity at room temperature. In this work, annealing engineered active edge sites of 2D SnO2 porous nanoplates were synthesized by a facile hydrothermal route. SnO2-600 2D semicircle nanoplates with small holes on its edge are attribute to their high sensitivity and selectivity to NO2 gas under the excitation of 365 nm UV light at room temperature. Density functional theory calculations show that the adsorption energy of −0.74 eV and the obvious variation in band gap before and after the interaction of NO2 on SnO2 (110). These results indicate high performance of gas sensitivity of SnO2 to NO2. The present studies provide useful strategies for the development of high selective room temperature SnO2-based NO2 sensors. Highlights: The SnO2 porous nanoplates with multiple active edge sites were successfully synthesized by a feasible hydrothermal method via adjusting annealing temperature. The fabricated SnO2-600 sensor displayed excellent NO2-sensing performance with fast response and recovery properties with the aid of UV excitation at room temperature. The gas sensing mechanism and gas selectivity mechanism are investigated by density functional theory calculations. [ABSTRACT FROM AUTHOR]

For most resistive sensors, the change of carrier concentration usually dominates the conductivity change in the gas sensing process, while the role of carrier mobility change is difficult to reflect. In this work, a ternary alloyed MoS2−xSex gas sensing material with high crystal quality and a carrier mobility-dominated gas-sensing (CMDGS) mode has been successfully prepared by a one-pot solvothermal method for the detection of NO2 gas. It is found that the alloyed MoS2−xSex nanocomposites with the best crystal quality have the lowest charge transfer resistance and baseline resistance, which can be attributed to the high carrier mobility and low carrier effective mass. The response of the best MoS2−xSex sensor to 50 ppm NO2 is as high as 92.8 at room temperature (25 °C) with a response and a recovery time of 25 and 22 s, respectively, which are about 42.0 times those of the MoS2 sensor. The actual and theoretical detection limits reach 10 ppb and 37.1 ppt, respectively. This study reveals that the CMDGS mode can be realized by improving the crystal quality and establishing the local built-in electric field of the sensing materials, which is more progressive than the carrier concentration-dominated gas sensing (CDDGS) mode. [ABSTRACT FROM AUTHOR]

Halide perovskites have attracted a great deal of attention due to their remarkable performances in solar cells, photodetectors, lasers, light emitting diodes, and memories. However, the issue of low quality of the halide perovskite films still restricts their potential applications. Here, the all-inorganic perovskite CsPbBr3 films prepared by the one-step solution deposition method are adopted as the switching layer to fabricate the flexible resistive switching (RS) memory devices. The devices exhibit a typical bipolar RS behavior including long data retention, high ON/OFF ratio, and good cycling endurance under bending, indicating that the one-step solution deposited CsPbBr3 films are promising candidates for the RS memory devices. In addition, by controlling the compliance current and applied stop voltage, the flexible RS devices demonstrate the multilevel storage capability. This work opens up the opportunity for future flexible, high performance, and multibit storage capability RS devices based on all-inorganic perovskite CsPbBr3 films. [ABSTRACT FROM AUTHOR]