Mesoporous WS 2 /MoO 3 hybrids were synthesized by a facile two-step and additive-free hydrothermal approach and employed for high-performance trace ammonia gas (NH 3 ) detection. Compared with single WS 2 and MoO 3 counterparts, WS 2 /MoO 3 sensors exhibited an improvement in NH 3 -sensing performance at room temperature (22 ± 3 °C). Typically, the optimal WS 2 /MoO 3 sensor showed a higher and quicker response of 31.58% within 57 s toward 3 ppm of NH 3 , which was 17.7-and 57.4-fold larger than that of pure MoO 3 (1.78% within 251 s) and WS 2 (0.55% within 153 s) ones. Meanwhile, good reversibility, sensitivity, and selectivity, reliable long-term stability, and the lowest detection limit of 9.0 ppb were achieved. These superior properties were probably ascribed to numerous heterojunctions favorable for additional carrier-concentration modulation via the synergetic effect between WS 2 and MoO 3 components and the large specific surface area beneficial for richer sorption sites and faster molecular transfer at room temperature. Such achievements also imply that the designed WS 2 /MoO 3 heterostructure nanomaterials have the potential in achieving trace NH 3 recognition catering for the requirements of high sensitivity and low power consumption in future gas sensors.

Herein, we report an environmentally stable and friendly halide perovskite based resistive random access memory device with an Ag/PMMA/ (PMA) 2 CuBr 4 /FTO (PMMA = poly(methyl methacrylate); PMA = C 6 H 5 CH 2 NH 3 ) architecture. The device exhibits the coexistence of two bipolar resistive switching modes, including counterclockwise and clockwise switching characteristics. The devices with both switching modes show stable endurance (>100 cycles) and long retention performance (>10 4 s). By applying a suitable electrical stimulation, the counterclockwise and clockwise switching behaviors are interconvertible. Furthermore, the Au/PMMA/(PMA) 2 CuBr 4 /FTO and Ag/ (PMA) 2 CuBr 4 /FTO devices were fabricated to verify the origin of dual resistive switching behaviors. The similar dual resistive switching behaviors after electroforming processes of three types of memory devices suggest that the interconvertible dual resistive switching characteristics could be attributed to the ionic migration in the (PMA) 2 CuBr 4 perovskite layer.

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Explosives can be analyzed for their content by detecting the photolytic gaseous byproducts. However, to prevent electrostatic sparking, explosives are frequently preserved in conditions with low temperatures and high humidity, impeding the performance of gas detection. Thus, it has become a research priority to develop gas sensors that operate at ambient temperature and high humidity levels in the realm of explosive breakdown gas-phase detection. In this work, 3-aminopropyltriethoxysilane (APTES) self-assembled monolayer-functionalized tin diselenide (APTES-SnSe 2 ) nanosheets were synthesized via a facile solution stirring strategy, resulting in a room-temperature NO 2 sensor with improved sensitivity and humidity tolerance. The APTES-SnSe 2 sensor with moderate functionalization time outperforms the pure SnSe 2 sensor in terms of the response value (317.51 vs 110.98%) and response deviation (3.11 vs 24.13%) under humidity interference to 500 ppb NO 2 . According to density functional theory simulations, the stronger adsorption of terminal amino groups of the APTES molecules to NO 2 molecules and stable adsorption energy in the presence of H 2 O are the causes of the improved sensing capabilities. Practically, the APTES-SnSe 2 sensor achieves accurate detection of photolysis gases from trace nitro explosives octogen, pentaerythritol tetranitrate, and trinitrotoluene at room temperature and various humidity levels. This study provides a potential strategy for the construction of gas sensors with high responsiveness and antihumidity capabilities to identify explosive content in harsh environments.

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