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Achieving rapid response and recovery rates at low operating temperatures for NO 2 is desirable for the application of sensors in industrial safety. In this study, we integrate a thickness tunable 2D graphdiyne (GDY) film into ZnO nanowalls (GDY/ZnO) via thermal evaporation of GDY, where ZnO nanowalls are used as the template to confine the growth space of the GDY film. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) is used to reveal the transformation process of NO 2. Ultraviolet photoemission spectroscopy (UPS) is utilized to analyze changes about the energy band of the materials. Density functional theory (DFT) calculations explain the reason for the selectivity of the samples to NO 2. The scanning electron microscopy (SEM) results demonstrate that the thickness of the GDY film with a specific mesoporous structure (25‐53 nm) increases as the thermal evaporation temperature rises from 400 to 800°C.The representative ZG-600, synthesized with a thickness of 46 nm via thermal evaporation at 600°C, exhibits superior NO 2 sensing performance. This is evidenced by its ultrahigh response (13.86, at 100 ppm and 150°C) and rapid response/recovery speeds (150 s/198 s), outperforming the ZnO sensor (198 s and 326 s). Moreover, it offers remarkable stability. • GDY nanoparticles were decorated on the surface of ZnO nanowall. • GDY/ZnO heterojunction with adsorbed oxygen and oxygen vacancies has been synthesized. • GDY/ZnO composite nanowall exhibited highly better NO 2 sensing performance. • The electrons transfer and redox reaction between GDY and ZnO has been discussed. [ABSTRACT FROM AUTHOR]

Ti 3 C 2 T x MXene, a novel 2D material, has shown promise in the field of room temperature ammonia (NH 3) sensors through theoretical calculations and experimental. However, the disadvantage of low response hinders its practical application. In this study, we fabricate a gas sensor based on Fe 2 O 3 nanoplate/TiO 2 nanoparticles supported by 2D Ti 3 C 2 T x MXene to enhance NH 3 sensing capabilities. Results reveal that the S2 sensor (with 3 mL FeCl 3) exhibits a significantly larger response value (3.23 times) and shorter response/recovery times (62 s and 74 s) compared to the pure Ti 3 C 2 T x MXene sensor when exposed to 100 ppm NH 3 at room temperature (25℃). Additionally, the S2 sensor exhibits a good linear response (R2 = 0.95) within the range of 1–100 ppm NH 3. The enhanced gas sensing properties can be mainly attributed to the Fe 2 O 3 /TiO 2 /Ti 3 C 2 T x MXene heterogeneous structure and unique microstructure. This study is anticipated to serve as a valuable reference for the advancement of high-performance MXene-based NH 3 sensors. • Fe 2 O 3 /TiO 2 /Ti 3 C 2 T x composite were prepared by a one-step solvothermal method. • The sensor exhibited good selectivity and stability for NH 3. • The sensor exhibited a low detection limit of 1 ppm to NH 3. • The sensing properties depend on the Schottky barrier and n-n heterojunction. [ABSTRACT FROM AUTHOR]

Design of practical tin oxide (SnO 2) semiconductor gas sensors is fundamental strategy to detect hazardous gases such as SO 2. However, challenges remain in the detection of SO 2 gas at low concentration and slow equilibrium between gas adsorption and desorption. Herein, the superior performance of nanostructured of Cu-doped flower-like SnO 2 architecture via feasible hydrothermal method demonstrated for the detection of SO 2 gas at low concentration (1–20 ppm) and fast gas adsorption and desorption equilibrium (14 s) towards 5 ppm SO 2. Furthermore, the as fabricated 3 mol% Cu-doped SnO 2 shows an outstanding gas response (∼ 4.05–20 ppm SO 2) at the working temperature of 300 ℃. The Cu-doping strategy may pave the way to ultrasensitive SO 2 gas sensor possessing low trace monitoring and fast equilibrium ability to satisfy the increasing demand for toxic SO 2 gas detection. • The Cu-doped flower-like SnO 2 architecture was prepared via feasible hydrothermal method. • The 3 mol% Cu-SnO 2 in the detection of SO 2 gas shows fast equilibrium and low trace monitoring (1 ppm). • The SO 2 sensing improvement reasons by doping of Cu was discussed. [ABSTRACT FROM AUTHOR]

Fast detection of triethylamine, one of the effective indicators to assess the freshness of fish and seafood, becomes more and more important for the food safety. Yet, the gas transport and diffuse activity are limited by the solid internal structure or the unsuitable pores size of the gas sensing materials, which results in the sluggish surface reaction kinetics. Herein, a strategy was reported to synthesis of hollow Co 3 O 4 microtubes assembled by vertically aligned nanosheets via sacrificial template of MgO combined with the following thermal annealing. The gas sensing results reveal that the hollow Co 3 O 4 -200 microtubes exhibit fast response-recovery time (13 s and 81 s) and outstanding gas selectivity, stability towards 200 ppm TEA at 180 ℃, which is ascribed to the large specific surface area, rich oxygen vacancies, and suitable pore size. This unique approach sheds light on the designing potential gas sensing candidates for the fast detection of TEA gas used as safety food monitoring and healthcare. • The hollow nanosheet-assembled Co3O4microtubes were synthesized via a simple sacrificial template strategy. • The fabricated Co3O4-200sensor displayed excellent TEA-sensing performance with fast response and recovery properties. • The large specific surface area and suitable pore size are the main reasons for the improved sensing properties. [ABSTRACT FROM AUTHOR]

In recent years, the potential use and development of acetone gas sensors in health monitoring and self-diagnostic applications has attracted increasing attention. Thus, accurate sensing of acetone is of crucial importance in the non-invasive diagnosis of diabetes. However, challenges remain in the detection of acetone, such as high concentrations detection limit, high operating temperature and slow response dynamics. Herein, vertically aligned Ce-doped mesoporous NiO nanowalls are prepared on Ag-Pd interdigitated electrode substrate using an in-situ growth method. The gas sensing performances show that the as-made 4 mol% Ce-doped NiO nanowalls has excellent gas response value (3.2) to 10 ppm acetone at a lower operating temperature (175 ℃) with fast adsorption and desorption equilibrium (13 s/7 s). Vertically aligned mesoporous NiO nanowalls doped by Ce element could pave the way for ultra-sensitive and low power consumption acetone gas sensors for breath gas detection. • Simple method: in situ growth method. • Excellent detection conditions: Low lower detection limits at lower temperatures. • The fast equilibrium of adsorption and desorption. [ABSTRACT FROM AUTHOR]

Realizing high gas response to triethylamine (TEA) are desirable for employment of sensors in applications of industrial safety and assessing the freshness of the seafood. Herein, a CuO/Co 3 O 4 heteojunction is proposed to improve the gas response performance via incorporating mesoporous CuO into nanosheet-assembled Co 3 O 4 microtubes. A novel approach to generate different proportion mesoporous CuO/Co 3 O 4 heterojunction is demonstrated, through which the morphologies can be fine-tuned. The resultant gas sensing performance shows that the Cu-Co-2 specimen exhibits the remarkably enhanced gas response value (7.6) to 200 ppm TEA, wide linear detection range (1–200 ppm), excellent repeatability and long-term stability as well as good gas selectivity to TEA gas at the working temperature of 320 ℃, which can be attributed to the surface active sites and the CuO/Co 3 O 4 heterointerface. This facile approach sheds lights on the design of sensing materials via construction of heterostructures for the high efficiency detection of target gas. • CuO/Co 3 O 4 composites were successfully prepared by a feasible water bath method. • An remarkably enhanced gas response to TEA at 320℃was obtained compared with the pristine Co 3 O 4. • The gas sensing mechanism is discussed from the perspective of heterojunction. [ABSTRACT FROM AUTHOR]