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3D nanoporous plasmonic chips for extremely sensitive NO <sub/>2</sub> detection
摘要： The detection of toxic gas molecules using the surface-enhanced Raman spectroscopy (SERS) technique is very challenging due to the low affinity of gas molecules. Here, we report extremely sensitive SERS-based NO2 gas sensors based on 3D nanoporous Au nanostructures with a high affinity for NO2 gas molecules and high density of hotspots.
关键词： SERS,toxic gas molecules,3D nanoporous plasmonic chips,surface-enhanced Raman spectroscopy,NO2 detection
更新于2025-09-12 10:27:22
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2D Plasmonic Tungsten Oxide Enabled Ultrasensitive Fiber Optics Gas Sensor
摘要： Functional materials coated on optical fibers have demonstrated great potential for optical gas sensing applications. However, their sensitivity is typically limited to the sub-parts per million (sub-ppm) range. Here, for the first time a 2D near-infrared plasmonic tungsten oxide (WOx) enabled ultrasensitive fiber optics gas sensor on a side-polished D-shape single mode optical fiber is presented. The plasmon resonance wavelength range of 2D WOx is matched with a conventional telecommunications wavelength of 1550 nm for driving the optical fiber, therefore inducing a strong light–matter interaction. Upon the surface adsorption of gas molecules, free electrons in the 2D WOx body are redistributed changing the plasmon resonance properties and hence the transmission through the optical fiber. The sensor is selectively responsive to NO2 at concentrations down to 44 parts per billion (ppb) with a limit of detection of 8 ppb at a relatively low elevated temperature. Such an excellent sensing performance is significantly improved over the previously reported fiber optics NO2 sensors, which suggests the integration of 2D plasmonic degenerated semiconductors as a viable approach to develop high-performance fiber optics gas sensors.
关键词： fiber optics,2D materials,NO2 gas sensors,plasmonic materials
更新于2025-09-11 14:15:04
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Enhanced NO2 gas-sensing properties of Au-Ag bimetal decorated MWCNTs/WO3 composite sensor under UV-LED irradiation
摘要： Novel NO2 gas sensors that were made of Ag, Au and Au-Ag bimetal particles modified composite of multi-walled carbon nanotubes/tungsten oxide (Ag/MWCNTs/WO3, Au/MWCNTs/WO3 and Au-Ag/MWCNTs/WO3) were fabricated for sensing ppb-level NO2 gas under ultraviolet light emitting diode (UV-LED) irradiation. The effects of Ag, Au and Au-Ag bimetal decoration and under UV-LED irradiation on the response of the Ag/MWCNTs/WO3, Au/MWCNTs/WO3 and Au-Ag/MWCNTs/WO3 sensors for sensing NO2 gas were studied. The gas-sensing properties in the detection of a low concentration of NO2 gas of the Au-Ag/MWCNTs/WO3 composite were superior to bare MWCNTs/WO3, Au/MWCNTs/WO3 and Ag/MWCNTs/WO3 under UV-LED irradiation. The Au-Ag/MWCNTs/WO3 composite sensor showed responses of 28–262 % at NO2 concentrations ranging from 100 to 500 ppb under UV-LED irradiation. These responses were 2–5 times higher than that of the bare MWCNTs/WO3 composite sensor at the same NO2 concentration range. The substantial improvement in the response of the bare MWCNTs/WO3 composite to NO2 gas by its decoration with Au-Ag bimetal particles may be attributed to the enhanced catalytically active sites and photocatalytic activity. A reasonable mechanism for enhancing sensitivity was proposed.
关键词： UV irradiation,NO2 gas sensor,Photocatalytic activity,Au-Ag bimetal
更新于2025-09-11 14:15:04
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MoS2 hybrid heterostructure thin film decorated with CdTe quantum dots for room temperature NO2 gas sensor
摘要： MoS2 hybrid heterostructure thin film decorated with CdTe quantum dots for room temperature NO2 gas sensor
关键词： Hybrid heterostructure,Sputtering,NO2 gas sensor,CdTe/MoS2 thin film
更新于2025-09-11 14:15:04
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The Synthesis of Polyethersulfone (PES) and its Derivatives as Polymer Light Emitting Diode (PLED) Material
摘要： Nowadays some types of polymer are being developed as Polymer Light Emitting Diode (PLED) materials because they have some advantages compared to small molecule organic light emitting diode (SM-OLED). Polymers which have numerous conjugated double bonds can be used as PLED materials, such as the polyethersulfone (PES) and its derivatives. Therefore, further research on the synthesis of PES and its derivatives is needed to explore their potential as PLED materials. In this research, the synthesis of polyethersulfone has been performed utilizing Microwave Assisted Organic Synthesis (MAOS) method and subsequently the synthesized PES was being transformed into the nitrated PES (PES-NO2) and the aminated PES (PES-NH2) utilizing the conventional method (reflux). The structure of the synthesized polymers was confirmed by analyzing the FT-IR and 1H-NMR spectra data. The potent of the synthesized polymers as PLED material was analyzed from fluorescence emission spectral data (in NMP, N-methyl pyrrolidone) showing the maximum emission wavelengths in the blue light of visible area, which were 444 nm (PES); 356 nm and 444 nm (PES-NO2); and 440 nm (PES-NH2). These results showed that all of the synthesized polymers have the potent to be used as PLED.
关键词： MAOS,PES-NO2,fluorescence,PES,PES-NH2,PLED
更新于2025-09-11 14:15:04
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Investigation of carrier density and mobility variations in graphene caused by surface adsorbates
摘要： Conductivity, carrier concentration and carrier mobility in graphene were investigated as a function of time in response to ionized donor and acceptor adsorbates. While a reduction in conductivity and hole density in graphene was observed upon exposure to a weak electron donor NH3, the carrier mobility was found to increase monotonically. The opposite behavior is observed upon exposure to NO2, which is expected based on its typical electron withdrawing property. Upon exposure to C9H22N2, a strong donor, it resulted in the transformation of graphene from p-type to n-type, although the inverse variation of carrier concentration and mobility was still observed. The variational trends remained unaltered even after intentional introduction of defects in graphene through exposure to oxygen plasma. The responses to C9H22N2, NH3 and NO2 exposures underline a strong influence by ionized surface adsorbates that we explained via a simple model considering charged impurity scattering of carriers in graphene.
关键词： Carrier density,Gas molecule adsorption,Graphene,Graphene mobility,NH3,NO2
更新于2025-09-10 09:29:36
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Tropospheric NO<sub>2</sub>, SO<sub>2</sub>, and HCHO over the East China Sea, using ship-based MAX-DOAS observations and comparison with OMI and OMPS satellite data
摘要： In this study, ship-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements were performed in the East China Sea (ECS) area in June 2017. The tropospheric slant column densities (SCDs) of nitrogen dioxide (NO2), sulfur dioxide (SO2), and formaldehyde (HCHO) were retrieved from the measured spectra using the differential optical absorption spectroscopy (DOAS) technique. Using the simple geometric approach, the SCDs of different trace gases observed at a 15? elevation angle were adopted to convert into tropospheric vertical column densities (VCDs). During this campaign, the averaged VCDs of NO2, SO2, and HCHO in the marine environment over the ECS area are 6.50 × 1015, 4.28 × 1015, and 7.39 × 1015 molec cm?2, respectively. In addition, the ship-based MAX-DOAS trace gas VCDs were compared with satellite observations of the Ozone Monitoring Instrument (OMI) and Ozone Mapping and Profiler Suite (OMPS). The daily OMI NO2 VCDs agreed well with ship-based MAX-DOAS measurements showing the correlation coefficient R of 0.83. In addition, the good agreements of SO2 and HCHO VCDs between the OMPS satellite and ship-based MAX-DOAS observations were also found, with correlation coefficients R of 0.76 and 0.69. The vertical profiles of these trace gases are achieved from the measured differential slant column densities (DSCDs) at different elevation angles using the optimal estimation method. The retrieved profiles displayed the typical vertical distribution characteristics, which exhibit low concentrations of < 3, < 3, and < 2 ppbv for NO2, SO2, and HCHO in a clean area of the marine boundary layer far from coast of the Yangtze River Delta (YRD) continental region. Interestingly, elevated SO2 concentrations can be observed intermittently along the ship routes, which is mainly attributed to the vicinal ship emissions in the view of the MAX-DOAS measurements. Combined with the onboard ozone lidar measurements, the ozone (O3) formation was discussed with the vertical profile of the HCHO/NO2 ratio, which is sensitive to increases in NO2 concentration. This study provided further understanding of the main air pollutants in the marine boundary layer of the ECS area and also benefited the formulation of policies regulating the shipping emissions in such costal areas like the YRD region.
关键词： OMPS,SO2,East China Sea,MAX-DOAS,HCHO,OMI,NO2
更新于2025-09-10 09:29:36
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A New Method to Prepare Few-Layers of Nanoclusters Decorated Graphene: Nb2O5/Graphene and Its Gas Sensing Properties
摘要： During the last decade, due to its excellent electrical, mechanical and thermal properties of chemically modified graphene has been extensively studied for many applications, such as polymer composites, energy-related materials, biomedical applications and sensors. The aim of this work is to evaluate the gas sensing performance of niobium oxide (Nb2O5) nanoclusters deposited onto few-layers graphene powder by magneton sputtering. Two different samples were prepared by changing electrical power of deposition. The materials were deeply morphologically, structurally and chemically characterized. Finally, they were deposited onto alumina substrates and their sensing properties were investigated vs. different gases, showing good sensing performance vs. ppm concentrations of NO2 at room temperature.
关键词： NO2 detection,room temperature,chemoresistive gas sensors,functionalized graphene
更新于2025-09-09 09:28:46
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Light-Assisted Room-Temperature NO2 Sensors Based on Black Sheet-Like NiO
摘要： In this study, we use two-dimensional black flake nickel oxide as the sensitive material which was synthesized by a facile hydrothermal route. The as-synthesized sheet-like NiO possessed a large specific surface area, as verified by BET characterization. The as-prepared NiO nanosheets had strong absorption in the range of 250–800 nm including UV and visible light. Upon exposure to ppb-level NO2, the presented sensors showed significant responses under light illumination at room temperature. In addition, the light wavelength also had a remarkable effect on the sensing performance in terms of sensitivity, response and recovery kinetics. Furthermore, the sensor showed a low humidity dependence.
关键词： NiO,light illumination,room temperature,NO2
更新于2025-09-09 09:28:46
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Investigations of Temporal and Spatial Distribution of Precursors SO<sub>2</sub> and NO<sub>2</sub> Vertical Columns in North China Plain by Mobile DOAS
摘要： Recently, Chinese cities have suffered severe events of haze air pollution, particularly in the North China Plain (NCP). Investigating the temporal and spatial distribution of pollutants, emissions, and pollution transport is necessary to better understand the effect of various sources on air quality. We report on mobile differential optical absorption spectroscopy (mobile DOAS) observations of 20 precursors SO2 and NO2 vertical columns in NCP in summer of 2013 (from 11 June to 7 July) in this study. The different temporal and spatial distributions of SO2 and NO2 vertical column density (VCD) over this area are characterized under various wind fields. The results show that the transport from southern NCP strongly affects the air quality in Beijing, and the transport route, particularly SO2 transport of Shijiazhuang–Baoding–Beijing is identified. In addition, the major contributors to SO2 along the route of Shijiazhuang–Baoding–Beijing are elevated sources and low area sources for the route of Dezhou–Cangzhou–Tianjin–Beijing are found using the interrelated analysis between in situ and mobile DOAS observations during the measurement periods. Furthermore, the discussion of hot spot near Ji’nan City shows that the average observed width of polluted air mass is 11.83 km and 17.23 km associated with air mass diffusion, which is approximately 60 km away from emission sources based on geometrical estimation. Finally, a reasonable agreement exists between OMI and mobile DOAS observations with correlation coefficient (R2) of 0.65 for NO2 VCDs. Both datasets also have similar spatial pattern. The fitted slop of 0.55 is significantly less than unity can reflect the contamination of local sources and OMI observations need to improve the sensitivities to the near-surface emission sources through the improvements of retrieval algorithm or resolution of satellites.
关键词： North China Plain,transport,air pollution,SO2,mobile DOAS,NO2
更新于2025-09-09 09:28:46