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Liquid crystal nose, chiral case: towards increased selectivity and low detection limits
摘要： In this paper, we describe a simple prototype of an olfaction system based on chiral liquid crystals (LCs) and suitable for sensing volatile organic compounds (VOCs). The detection of small concentrations of VOCs is based on measuring weak colour fluctuations on the surface of the LC droplet. Detection of larger concentrations is based on measuring colour changes (or shift of the selective reflection band) and isotropisation transition of the whole droplet. Thus, a broad range of VOC concentrations can be detected by this LC nose.
关键词： gas detection,LC nose,volatile organic compound,olfaction,electronic nose,VOC,liquid crystals,cholesteric
更新于2025-09-23 15:22:29
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Integrated adsorption and photocatalytic degradation of volatile organic compounds (VOCs) using carbon-based nanocomposites: A critical review
摘要： Volatile organic compounds (VOCs) are harmful for human and surrounding ecosystem, and a great number of VOC abatement technologies have been developed during the past few decades. However, the single method has some problems such as high energy consumption, unfriendly environment, and low removal efficiency. Recently, the integration of adsorption and photocatalytic degradation of VOCs is considered as a promising one. Carbon material, with large surface area, high adsorption capacity, and fast electron transfer ability, is widely used in integrated adsorptive-photocatalytic removal of VOCs. It is thus crucial to digest and summarize recent research advances in carbon-based nanocomposites as the adsorbent-photocatalyst for VOC removal. To satisfy this need, this work provides a critical review of the related literature with focuses on: (1) the advantages and disadvantages of various carbon-based nanocomposites for the applications of VOC adsorption and photocatalytic degradation; (2) models and mechanisms of adsorptive-photocatalytic removal of VOCs according to the material properties; and (3) major factors controlling adsorption-photocatalysis processes of VOCs. The review is aimed to establish the "structure-property-application" relationships for the development of innovative carbon-supported nanocomposites and to promote future research on the integrated adsorptive and photocatalytic removal of VOCs.
关键词： Modeling,Photocatalytic degradation,VOC abatement,Carbon-based nanocomposite,Adsorption
更新于2025-09-23 15:21:21
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[IEEE 2020 IEEE 11th Latin American Symposium on Circuits & Systems (LASCAS) - San Jose, Costa Rica (2020.2.25-2020.2.28)] 2020 IEEE 11th Latin American Symposium on Circuits & Systems (LASCAS) - Advancing Uncooled Infrared Imagers Using An Open-Circuit Voltage Pixel
摘要： A topology leveraging a photodetector in the forward bias region generating an open-circuit voltage is proposed. Connecting the anode of the photodetector to the gate of a MOSFET device operating in the subthreshold region provides the basis for a new open-circuit voltage pixel (VocP). Theoretical analysis outlining the effective photodetector response and performance benefits is described. An integrated circuit (IC) with direct-injection pixels modified to support the VocP front-end and analog output readout fabricated in a CMOS 0.18 μm technology is also presented. The IC allows testing of mid-wave infrared (IR) photodiodes operating in both the photocurrent and VocP modes. The VocP pixel is compared to a traditional reverse bias current mode photodetector configuration. Simulation, modeling, and measurement show improved sensitivity and faster response time for the VocP over direct photocurrent detection.
关键词： model,ROIC,open-circuit voltage,readout,MWIR,Mid-wave,Voc
更新于2025-09-23 15:21:01
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Revisiting cocatalyst/TiO2 photocatalyst in blue light photothermalcatalysis
摘要： Coupling heat into photocatalysis (PC) has been found more efficient than PC for removal of volatile organic compounds (VOC). Therein, photothermal synergy induced photothermalcatalysis (PTC) sometimes tells different stories from PC. In this work, we revisit ST-01 TiO2 photocatalyst as photothermalcatalyst under blue light at 333 K and further investigate the role of surface grafted cocatalyst (CrxO, CoxO, CuxO, Pt) in catalytic removal of gaseous acetaldehyde pollutant. By comparison on the amount of cocatalyst, for PC, more CrxO cocatalyst (3 wt%) is favored for higher removal efficiency of acetaldehyde. For PTC, less CrxO cocatalyst (0.3 wt%) is favored. By further comparison on the type of cocatalyst, for PC, hole cocatalyst (CrxO and CoxO) gives inferior performance to that of electron cocatalyst (CuxO and Pt). For PTC, hole cocatalyst gives superior performance to that of electron cocatalyst. The difference between PC and PTC lies in synergistic effect between defect-related blue-light absorption, cocatalyst induced interfacial charge transfer and matched surface red-ox reaction rate. This work may provide new insight into the design and development of photothermalcatalyst for VOC removal.
关键词： Cocatalyst,VOC removal,Photothermal synergy,Photocatalytic,Photothermalcatalytic
更新于2025-09-23 15:21:01
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Effects of weathering on the performance of self-cleaning photocatalytic paints
摘要： The use of photocatalytic products for the surface coating of buildings is spreading more and more, because of the reduction of atmospheric pollutants and the colour maintenance of the paints over time with reduction of the maintenance costs and the improvement of the aesthetic appearance. The study reports the evaluation of the effects of the atmospheric conditions on three commercial photocatalytic paints containing TiO2. In particular tests were carried out by using samples subjected to accelerated aging inside a climate chamber and naturally aged by exposure for two years to the external environment of the city of Palermo (representative of a coastal environment of the Mediterranean basin). The samples were characterized by Scanning Electron Microscopy (SEM) and Optical Microscopy to evaluate the surface morphology, and by UV–Vis Spectrophotometry to appreciate the colours changes as a result of aging. X-ray diffraction (XRD), moreover, was used to identify the TiO2 phase and static contact angles were determined to evaluate the surface hydrophilicity. The photocatalytic activity was evaluated under UV and solar light irradiation by degrading 2-propanol, used as a probe molecule and analysed by gas chromatography (GC), which is representative of volatile organic compounds (VOC's). The results indicated colour conservation, increase of the surface hydrophilicity and maintenance of the photocatalytic performances.
关键词： Static contact angle,Titanium dioxide,Photocatalytic paints,VOC'S degradation,Weathering effects
更新于2025-09-23 15:21:01
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Outdoor manufacture of UV-Cured plastic linings for storm water culvert repair: Chemical emissions and residual
摘要： Storm water culverts are integral for U.S. public safety and welfare, and their mechanical failure can cause roadways to collapse. To repair these buried assets, ultraviolet (UV) light cured-in-place-pipes (CIPP) are being installed. Chemical emission and residual material left behind from the installation process was investigated in New York and Virginia. Samples of an uncured resin tube and field-cured styrene-based resin CIPPs were collected and analyzed. Also collected were air and water samples before, during, and after installations. Chemicals were emitted into air because of the installation and curing processes. Particulates emitted into the air, water, and soil contained fiberglass, polymer, and contaminants, some of which are regulated by state-level water quality standards. The uncured resin tube contained more than 70 chemical compounds, and 19 were confirmed with analytical standards. Compounds included known and suspected carcinogens, endocrine disrupting compounds, hazardous air pollutants, and other compounds with little aquatic toxicity data available. Compounds (14 of 19 confirmed) were extracted from the newly installed CIPPs, and 11 were found in water samples. Aqueous styrene (2.31 mg/L), dibutyl phthalate (12.5 μg/L), and phenol (16.7 μg/L) levels exceeded the most stringent state water quality standards chosen in this study. Styrene was the only compound that was found to have exceed a 48 hr aquatic toxicity threshold. Newly installed CIPPs contained a significant amount volatile material (1.0-6.8 wt%). Recommendations provided can reduce chemical emission, as well as improve worksite and environmental protection practices. Recommended future research is also described.
关键词： VOC,styrene,Plastic lining,sewer pipe,cured in place pipe,resin
更新于2025-09-23 15:21:01
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Hybrid chemical bath deposition-CdS/sputter-Zn(O,S) alternative buffer for Cu <sub/>2</sub> ZnSn(S,Se) <sub/>4</sub> based solar cells
摘要： To replace the conventionally used CdS buffers in Cu2ZnSn(S,Se)4 (CZTSSe) based thin-film solar cells, sputtered Zn(O,S) buffer layers have been investigated. Zn(O,S) layers with three different [O]/([O] + [S]) ratios (0.4, 0.7, and 0.8)—and a combination of Zn(O,S) and CdS (“hybrid buffer layer”) were studied. In comparison to the CdS reference, the external quantum efficiency (EQE) of the Zn(O,S)-buffered devices increases in the short- and long-wavelength regions of the spectrum. However, the average EQE ranges below that of the CdS reference, and the devices show a low open-circuit voltage (VOC). By adding a very thin CdS layer (5 nm) between the absorber and the Zn(O,S) buffer, the VOC loss is completely avoided. Using thicker intermediate CdS layers result in a further device improvement, with VOC values above those of the CdS reference. X-ray photoelectron spectroscopy (XPS) measurements suggest that the thin CdS layer prevents damage to the absorber surface during the sputter deposition of the Zn(O,S) buffer. With the hybrid buffer configuration, a record VOC deficit, i.e., a minimum difference between bandgap energy Eg (divided by the elementary charge q) and VOC (Eg/q – VOC) of 519 mV could be obtained, i.e., the lowest value reported for kesterite solar cells to date. Thus, the hybrid buffer configuration is a promising approach to overcome one of the main bottlenecks of kesterite-based solar cells, while simultaneously also reducing the amount of cadmium needed in the device.
关键词： VOC deficit,Cu2ZnSn(S,Se)4,CdS,hybrid buffer layer,open-circuit voltage,X-ray photoelectron spectroscopy,thin-film solar cells,Zn(O,S) buffer layers,external quantum efficiency
更新于2025-09-23 15:19:57
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A single light spot GC detector employing localized surface plasmon resonance of porous Au@SiO <sub/>2</sub> nanoparticle multilayer
摘要： This paper describes the synthesis of a nano-porous multilayered film consisting of Au@SiO2 nanoparticles. This film was used to miniaturize the size of a localized surface plasmon resonance (LSPR)-based capillary gas chromatograph (GC) detector. A layer-by-layer (LbL) approach with proper surface reaction sequences was used to create a multilayer structure that consisted of as many as five layers of Au@SiO2 nanoparticles. The center wavelength of LSPR was shifted from 520 to 634 nm due to the approximation of additional layers of nanoparticles. The vapor response time for this Au@SiO2 multilayer LSPR sensor was identical to that of an Au nanoparticle monolayer, which confirmed that this multilayer structure has a high level of gas permeability. The multilayer was synthesized inside a glass capillary for use as a GC detector. Due to the enhancement of absorbance, the gas chromatographic signal was obtained via a single spotlight that penetrated one side of the glass capillary and was then reflected by a silver mirror coated on the opposite side. The detection limits were ≤20 ng for cyclohexanone and m-xylene.
关键词： gas chromatography,localized surface plasmon resonance,multilayer film,miniaturization,Au@SiO2 nanoparticles,VOC detection
更新于2025-09-19 17:15:36
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Enhancement of open circuit voltage of CdTe solar cell
摘要： In the present work, FTO/CdS/CdTe/Te/Al superstrate structured solar cell has been fabricated using thermal evaporation method. A 40 nm thin layer of P-type tellurium has been incorporated between CdTe and back contact to reduce the potential energy barrier by improving the quality of interfaces. The fabricated device characterized using UV–Visible-NIR spectroscopy and I–V measurement. The tellurium interlayer plays a vital role in enhancing the performance of the device. The fabricated device generated open circuit voltage (Voc) of 0.7 V.
关键词： Open-circuit voltage (Voc),I–V characteristics,Thermal evaporator,Solar cell,Cadmium Telluride (CdTe),UV–Visible-NIR spectroscopy
更新于2025-09-19 17:13:59
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Cesium Lead Inorganic Solar Cell with Efficiency beyond 18% via Reduced Charge Recombination
摘要： Cesium-based inorganic perovskite solar cells (PSCs) are promising due to their potential for improving device stability. However, the power conversion efficiency of the inorganic PSCs is still low compared with the hybrid PSCs due to the large open-circuit voltage (VOC) loss possibly caused by charge recombination. The use of an insulated shunt-blocking layer lithium fluoride on electron transport layer SnO2 for better energy level alignment with the conduction band minimum of the CsPbI3-xBrx and also for interface defect passivation is reported. In addition, by incorporating lead chloride in CsPbI3-xBrx precursor, the perovskite film crystallinity is significantly enhanced and the charge recombination in perovksite is suppressed. As a result, optimized CsPbI3-xBrx PSCs with a band gap of 1.77 eV exhibit excellent performance with the best VOC as high as 1.25 V and an efficiency of 18.64%. Meanwhile, a high photostability with a less than 6% efficiency drop is achieved for CsPbI3-xBrx PSCs under continuous 1 sun equivalent illumination over 1000 h.
关键词： VOC loss,inorganic perovskite solar cells,recombination defects
更新于2025-09-19 17:13:59