Search

Highlights • Tin oxide/reduced graphene oxide/polyaniline (SnO 2 /rGO/PANI) nanohybrid was fabricated by in-situ polymerization route. • The SnO 2 /rGO/PANI nanocomposite exhibited excellent sensing properties for H 2 S gas detection. • The sensing mechanism was ascribed to the unique nanostructure, catalytic effect and p-n heterojunction. Abstract A room temperature sub-ppb hydrogen sulfide (H 2 S) gas sensors based on tin oxide/reduced graphene oxide/polyaniline (SnO 2 /rGO/PANI) was synthesized by in-situ polymerization technique. The SnO 2 /rGO/PANI nanocomposite film was fabricated on a flexible polyethylene terephthalate (PET) substrate with interdigital electrodes (IDEs). The SnO 2 /rGO/PANI sensor possesses excellent sensing characteristics such as high response, fast response/recovery time, stable repeatability, outstanding selectivity and long-term stability. The response of SnO 2 /rGO/PANI film sensor prepared by in-situ polymerization is 23.9 toward 200 ppb H 2 S, which is two times higher than that of physical doping method, and the limit of detection is 50 ppb. The experimental result reveals that the SnO 2 /rGO/PANI sensor is an excellent candidate to detect H 2 S gas in exhaled human breath for early diagnosis of halitosis. The underlying sensing mechanism of the SnO 2 /rGO/PANI sensing device towards H 2 S gas is due to the high surface area of SnO 2 /rGO/PANI film, chemisorption of oxygen on surface of SnO 2 hollow spheres and the special role of heterojunction. [ABSTRACT FROM AUTHOR]

Highlights • MOF-derived ZnO nanopolyhedra/S, N: graphene quantum dots/polyaniline (ZnO/S, N: GQDs/PANI) hybrid was fabricated. • The ZnO/S, N: GQDs/PANI composite exhibited excellent sensing properties for acetone gas detection. • The gas sensing mechanism was ascribed to the unique nanostructure, catalytic effect and p-n heterojunction. Abstract Metal-organic frameworks-derived zinc oxide nanopolyhedra/S, N: graphene quantum dots/polyaniline (ZnO/S, N: GQDs/PANI) ternary nanohybrid was synthesized by in-situ polymerization route. The ZnO/S, N: GQDs/PANI nanocomposite was fabricated on a flexible polyethylene terephthalate (PET) substrate with interdigital electrodes. The acetone-sensing properties of the ZnO/S, N: GQDs/PANI nanocomposite sensor were investigated by exposing it to various concentrations of acetone at room temperature. The ZnO/S, N: GQDs/PANI sensor demonstrated high response, fast response/recovery time, stable repeatability, excellent selectivity, outstanding long-term stability, and ppb-level sensitivity for trace acetone detection at room temperature. These results render the ZnO/S, N: GQDs/PANI film sensor a promising candidate for acetone sensing at room temperature. The underlying sensing mechanism of the ZnO/S, N: GQDs/PANI sensor toward acetone gas ascribed to the synergistic effect and heterojunction created in the ZnO/S, N: GQDs/PANI nanocomposite. [ABSTRACT FROM AUTHOR]

Highlights • PPy/Zn 2 SnO 4 nanofilm–based ammonia sensor was fabricated via layer-by-layer self-assembly. • Ultrahigh ammonia-sensing properties of PPy/Zn 2 SnO 4 nanofilm sensor were demonstrated. • The sensing mechanism for the PPy/Zn 2 SnO 4 nanofilm sensor toward ammonia was discussed. Abstract This paper demonstrates an ultra-highly sensitive ammonia gas sensor based on polypyrrole/zinc stannate (PPy/Zn 2 SnO 4) nanocomposite. The PPy/Zn 2 SnO 4 nanocomposite was synthesized by layer-by-layer alternative deposition of PPy nanospheres and Zn 2 SnO 4 hollow spheres. The as-prepared sample was characterized by X-ray diffraction (XRD), FT-IR spectrums, scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM). The gas-sensing properties of the PPy/Zn 2 SnO 4 nanofilm were investigated upon exposure to ammonia gas. The result showed that the PPy/Zn 2 SnO 4 nanofilm sensor exhibited lower detection limit, higher response, faster response/recovery time, outstanding repeatability toward NH 3 gas, which was greatly superior to the pure PPy and Zn 2 SnO 4 counterparts. Such dramatically enhancement of gas-sensing properties for PPy/Zn 2 SnO 4 nanofilm is attributed to the deprotonation/protonation process of ammonia adsorption/desorption on PPy surface, special interactions at p-n heterojunction, and high surface area of PPy/Zn 2 SnO 4 nanocomposite. [ABSTRACT FROM AUTHOR]

This paper reports a high-performance room-temperature ammonia gas sensor based on polyaniline/multi-walled carbon nanotubes/molybdenum disulfide (PANI/MWCNTs/MoS 2 ) ternary nanocomposite prepared via in-situ chemical oxidative polymerization method. The component, morphology, crystallinity, and chemical state of PANI/MWCNTs/MoS 2 sample was fully inspected by X-ray diffraction (XRD), fourier transform infrared spectrometer (FT-IR), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM), confirming its successful fabrication and reasonability. The ammonia sensing properties of PANI/MWCNTs/MoS 2 nanocomposite were investigated at room temperature. The experimental results exhibited excellent properties in terms of high response, fast response/recovery time as well as outstanding repeatability, which were greatly superior to the pure PANI, PANI/MWCNTs and PANI/MoS 2 film counterparts. Finally, the potential ammonia-sensing mechanism of the PANI/MWCNTs/MoS 2 nanocomposite was systematically discussed, which is attributed to the synergistic effect of the ternary nanomaterials and special interactions at p-n heterojunction. [ABSTRACT FROM AUTHOR]

Highlights • Tin disulfide/graphene oxide nanoflower (SnS 2 /GO) was firstly prepared on a flexible PET substrate. • The SnS 2 /GO film sensor shows ultrasensitive humidity sensing with ultralow hysteresis and good reversibility. • The SnS 2 /GO film humidity sensor demonstrated a great potential for wearable applications. Abstract Flexible humidity sensors with ultrafast response are great importance in the promising wearable devices. In this paper, a novel nanocomposite of tin disulfide/graphene oxide nanoflower (SnS 2 /GO) was first synthesized for constructing humidity sensors. The nanostructural, morphological and compositional properties of the SnS 2 /GO hybrid were characterized by XRD, XPS, FT-IR, SEM, TEM and EDS. The humidity experiment found that SnS 2 /GO (in the wt% ratio of 1:2.5) has the most excellent response. The humidity sensing results revealed the SnS 2 /GO film sensor has ultrahigh response, negligible hysteresis, favorable reversibility and ultrafast response/recovery behavior, which outstrips the individual SnS 2 or GO film sensor. The potential mechanism of water molecule adsorption was revealed, and the complex impedance spectroscopy and Bode diagrams were used to further explain the sensing mechanisms of the SnS 2 /GO composite. Moreover, the impedance changes caused by the bending effect, human respiration and fingertip approaching/retracting behavior were investigated, which demonstrate a great potential of the SnS 2 /GO sensor in humidity sensing for wearable applications. [ABSTRACT FROM AUTHOR]

Highlights • MOFs-derived hollow ZnO/Co 3 O 4 polyhedrons nanoheterostructure was fabricated. • The ZnO/Co 3 O 4 nanoheterostructure exhibited excellent sensing properties toward acetone gas. • The sensing mechanism was ascribed to the unique nanostructure, catalytic effect and p-n heterojunction. Abstract A high-performance acetone gas sensor based on metal-organic frameworks (MOFs)-derived ZnO/Co 3 O 4 nano-heterostructure was prepared by a facile precipitation reaction method. The as-synthesized ZnO/Co 3 O 4 nanocomposite was characterized by X-ray diffraction (XRD), thermo-gravimetric (TG), scanning electron microscopy (SEM), energy dispersive X-ray spectra (EDS), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), confirming its successful preparation and reasonability. The acetone sensing properties of ZnO/Co 3 O 4 hollow polyhedron sample was investigated at the optimum working temperature of 300 °C. The experimental results reveal that the ZnO/Co 3 O 4 nanocomposite has a significantly enhancement in acetone sensing performance, which showed high response, good linearity, short response/recovery time, excellent repeatability and outstanding selectivity. These results render the ZnO/Co 3 O 4 hollow polyhedron an efficient sensing material for constructing high-performance acetone sensor. The mechanism of the enhanced acetone sensing performance were attributed to unique hollow nanostructure, catalytic effect of Co 3 O 4 and the p-n heterojunctions in the ZnO/Co 3 O 4 nanocomposite. [ABSTRACT FROM AUTHOR]

An ultrahigh-performance impedance-type humidity sensor based on tin disulfide (SnS 2 )/titanium dioxide (TiO 2 ) nanocomposite was demonstrated via layer-by-layer self-assembly technique in this work. The nanostructures, morphologies, composition properties of the SnS 2 /TiO 2 nanocomposite were fully examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The humidity sensing characteristics of the SnS 2 /TiO 2 film sensor were investigated at room temperature. The results show that the SnS 2 /TiO 2 film sensor has an impedance response up to 200050 and a sensitivity of 442000 Ω/%RH, which is much better than that of the existing humidity sensors. Excellent stability and repeatability are also exhibited for the SnS 2 /TiO 2 film sensor. Moreover, the underlying sensing mechanism for the SnS 2 /TiO 2 sensor toward humidity was explored with the complex impedance spectroscopy and the Bode diagram. The SnS 2 /TiO 2 nanocomposite provides a promising building block for ultrahigh-sensitive humidity sensing and detection of human respiratory. [ABSTRACT FROM AUTHOR]

The extraordinary properties of black phosphorus (BP) make it an attracting candidate for next-generation chemical sensors. BP is strain-sensitive due to piezoresistive effect, but the impact of strain on BP chemical sensing performance is still unknown which is critical to flexible devices. Additionally, BP sensor integration is highly desired because of the complexity of real samples, but it remains only theoretically explored. Here, we developed flexible integrated BP sensor arrays (FIBA) functionalized with ionophore, which demonstrated excellent mechanical flexibility (strain limits of 1%) and stability (bending 500 times). Small strain variation (from 0.33% to −0.16%) resulted in 175% enhancement of sensitivity due to Schottky barrier modulation. Rapid (4 s) label-free detection of 1 μg/L Hg 2+ was achieved, within the permissible limit of the guideline for drinking water quality provided by the World Health Organization (WHO). The low-cost simple-structured FIBA realized multiplexed detection of Hg 2+ , Cd 2+ , Pb 2+ , and Na + at trace concentration with excellent selectivity. FIBA also exhibited the ability of monitoring target ions in real samples (Cd 2+ in tap water and Na + in human sweat). These results demonstrate that FIBA is a promising candidate for wide range of vital signs or environment monitoring. [ABSTRACT FROM AUTHOR]