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Selective H2S-sensing performance of Si nanowires through the formation of ZnO shells with Au functionalization
摘要： A novel gas sensor fabricated from ZnO-shelled Si nanowires (SiNWs) is presented. After coating a thin layer of Au on the surfaces of Si NWs, ZnO layers were formed on the surfaces of p-SiNWs by thermal evaporation of Zn powders and a subsequent oxidation process. Microscopic analysis confirmed the successful formation of ZnO-Si core-shell NWs with Au nanoparticles present on the shell surface. The gas sensing performance of the gas sensor fabricated using the p-Si/n-ZnO core-shell NWs was evaluated for various gases. The sensor exhibited outstanding response and selectivity to H2S gas. The gas sensing mechanism was evaluated in detail and attributed to various factors, including the formation of ZnO/Si and Au/ZnO heterojunctions and the chemical attraction between ZnO and Au. The results demonstrate a new sensing material for H2S detection in various fields that can be easily incorporated into Si-based devices.
关键词： Gas Sensor,Si Nanowires,ZnO,Sensing Mechanism,Shell,Au
更新于2025-11-14 15:15:56
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A Gas Sensor Based on a Single SnO Micro-Disk
摘要： In this study, individual nanofabricated SnO micro-disks, previously shown to exhibit exceptional sensitivity to NOx, are investigated to further our understanding of gas sensing mechanisms. The SnO disks presenting different areas and thickness were isolated and electrically connected to metallic electrodes aided by a Dual Beam Microscope (SEM/FIB). While single micro-disk devices were found to exhibit short response and recovery times and low power consumption, large interconnected arrays of micro-disks exhibit much higher sensitivity and selectivity. The source of these differences is discussed based on the gas/solid interaction and transport mechanisms, which showed that thickness plays a major role during the gas sensing of single-devices. The calculated Debye length of the SnO disk in presence of NO2 is reported for the first time.
关键词： single-element device,FIB nanofabrication,low power consumption,semiconductor,sensing mechanism,Debye length,gas sensor,SnO
更新于2025-09-23 15:21:01
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High Operation Stability and Different Sensing Mechanisms in Graphene Oxide Gel Photodetectors Utilizing a Thin Polymeric Layer
摘要： We report a significant improvement in the operational stability and photosensitivity of an interdigitated photodetector using a hybrid sensing material based on a reduced graphene oxide gel (femtogel) and poly methyl methacrylate (PMMA). By coating the reduced graphene oxide photodetector with a protective layer of PMMA, a noticeable current stability is achieved, either during a sweep or fixed voltage, compared to an unprotected photodetector. A bolometric-effect sensing mechanism was observed in the unprotected photodetector, whereas the hybrid PMMA/femtogel photodetector displayed a photovoltaic-effect sensing mechanism. This change in the sensing mechanism of the graphene-based device, as a result of encapsulating the sensing area using a polymeric thin layer, is reported for the first time. Moreover, a higher and reliable sensitivity to the low-power illumination source was observed in the hybrid PMMA/femtogel photodetector. This study provides an avenue for engineering the performance and reliability of graphene oxide photodetectors that operate in an ambient environment in order to solve the current bottleneck issue, resulting from lack of reliability, in commercializing these material.
关键词： Bolometric effect,Sensing mechanism,PMMA,Photodetector,Graphene oxide,Graphene gel
更新于2025-09-23 15:19:57
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New perspective on the fluorescence and sensing mechanism of TNP chemosensor 2-(4,5-bis(4-chlorophenyl)-1H-imidazol-2-yl)-4-chlorolphenol
摘要： For TNP chemosensor 2-(4,5-Bis(4-Chlorophenyl)-1H-Imidazol-2-yl)-4-Chlorolphenol (HPICI), previous thought with no theoretical basis was that excited-state intramolecular proton transfer (ESIPT) process and the ground-state HPICI-TNP complex are mainly responsible for its fluorescence emission and the detection of TNP. However, this interpretation has been proved to be wrong by the present theoretical DFT/TDDFT explorations. Actually, the strong fluorescence of HPICI is mainly induced by the local excitation of the enol form HPICI(E) without ESIPT, and the fluorescence quenching by TNP is due to the photo-induced electron transfer (PET) process together with the cooperative effect of hydrogen-bonding interaction and π-π stacking interaction coexisting in the HPICI-TNP complex. The strengthened excited-state hydrogen bond promotes the PET process, thus facilitates the fluorescence quenching. This mechanism is proposed on the basis of the theoretical analyses on molecule geometry, binding energy, Gibbs free energy, electronic transitions, and frontier molecular orbitals (FMOs).
关键词： Fluorescence emission,Fluorescence quenching,Photo-induced electron transfer,Hydrogen-bonding interaction,Dynamical sensing mechanism,π-π stacking interaction
更新于2025-09-19 17:15:36
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Review—System-on-Chip SMO Gas Sensor Integration in Advanced CMOS Technology
摘要： The growing demand for the integration of functionalities on a single device is peaking with the rise of IoT. We are near to having multiple sensors in portable and wearable technologies, made possible through integration of sensor fabrication with mature CMOS manufacturing. In this paper we address semiconductor metal oxide sensors, which have the potential to become a universal sensor since they can be used in many emerging applications. This review concentrates on the gas sensing capabilities of the sensor and summarizes achievements in modeling relevant materials and processes for these emerging devices. Recent advances in sensor fabrication and the modeling thereof are further discussed, followed by a description of the essential electro-thermal-mechanical analyses, employed to estimate the devices’ mechanical reliability. We further address advances made in understanding the sensing layer, which can be modeled similar to a transistor, where instead of a gate contact, the ionosorped gas ions create a surface potential, changing the film’s conduction. Due to the intricate nature of the porous sensing films and the reception-transduction mechanism, many added complexities must be addressed. The importance of a thorough understanding of the electro-thermal-mechanical problem and how it links to the operation of the sensing film is thereby highlighted.
关键词： SMO gas sensors,CMOS integration,sensing mechanism,modeling,microheater design
更新于2025-09-19 17:15:36
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Fluorescence Characteristics of Aqueous Synthesized Tin Oxide Quantum Dots for the Detection of Heavy Metal Ions in Contaminated Water
摘要： Tin oxide quantum dots were synthesized in aqueous solution via a simple hydrolysis and oxidation process. The morphology observation showed that the quantum dots had an average grain size of 2.23 nm. The rutile phase SnO2 was confirmed by the structural and compositional characterization. The fluorescence spectroscopy of quantum dots was used to detect the heavy metal ions of Cd2+, Fe3+, Ni2+ and Pb2+, which caused the quenching effect of photoluminescence. The quantum dots showed the response of 2.48 to 100 ppm Ni2+. The prepared SnO2 quantum dots exhibited prospective in the detection of heavy metal ions in contaminated water, including deionized water, deionized water with Fe3+, reclaimed water and sea water. The limit of detection was as low as 0.01 ppm for Ni2+ detection. The first principle calculation based on the density function theory demonstrated the dependence of fluorescence response on the adsorption energy of heavy metal ions as well as ion radius. The mechanism of fluorescence response was discussed based on the interaction between Sn vacancies and Ni2+ ions. A linear correlation of fluorescence emission intensity against Ni2+ concentration was obtained in the logarithmic coordinates. The density of active Sn vacancies was the crucial factor that determined fluorescence response of SnO2 QDs to heavy metal ions.
关键词： heavy metal ion,tin oxide,fluorescence,quantum dot,sensing mechanism,water pollution
更新于2025-09-11 14:15:04
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Highly sensitive air stable easily processable gas sensors based on Langmuir-Schaefer monolayer organic field-effect transistors for multiparametric H <sub/>2</sub> S and NH <sub/>3</sub> real-time detection
摘要： A combination of low limit of detection, low power consumption and portability makes organic field-effect transistors (OFETs) chemical sensors promising for various applications in the areas of industrial safety control, food spoilage detection and medical diagnostics. However, the OFET sensors typically lack air stability and restoration capability at room temperature. Here we report on a new design of highly sensitive gas sensors based on Langmuir-Schaefer monolayer organic field-effect transistors (LS OFETs) prepared from organosilicon derivative of [1]benzothieno[3,2-b][1]-benzothiophene. The devices fabricated are able to operate in air and allows an ultrafast detection of different analytes at low concentrations down to tens ppb. The sensors are reusable and can be utilized in real-time air quality monitoring systems. We show that a direct current response of the LS OFET can be splitted into the alteration of various transistor parameters, responsible for the interactions with different toxic gases. The sensor response acquiring approach developed allows distinguishing two different gases, H2S and NH3, with a single sensing device. The results reported open new perspectives for the OFET-based gas-sensing technology and pave the way to easy detection of the other types of gases enabling the development of complex air analysis systems based on a single sensor.
关键词： Multiparametric detection,Sensing mechanism,Monolayer organic field-effect transistors,Langmuir-Schaefer monolayers,Chemical sensors
更新于2025-09-11 14:15:04
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Gas Sensing Performances of ZnO Hierarchical Structures for Detecting Dissolved Gases in Transformer Oil: A Mini Review
摘要： Power transformer is one of the critical and expensive apparatus in high voltage power system. Hence, using highly efficient gas sensors to real-time monitor the fault characteristic gases dissolved in transformer oil is in pressing need to ensure the smooth functionalization of the power system. Till date, as a semiconductor metal oxide, zinc oxide (ZnO) is considered as the promising resistive-type gas sensing material. However, the elevated operating temperature, slow response, poor selectivity and stability limit its extensive applications in the field of dissolved gases monitoring. In this respect, rigorous efforts have been made to offset the above-mentioned shortcomings by multiple strategies. In this review, we first introduce the various ZnO hierarchical structures which possess high surface areas and less aggregation, as well as their corresponding gas sensing performances. Then, the primary parameters (sensitivity, selectivity and stability) which affect the performances of ZnO hierarchical structures based gas sensors are discussed in detail. Much more attention is particularly paid to the improvement strategies of enhancing these parameters, mainly including surface modification, additive doping and ultraviolet (UV) light activation. We finally review gas sensing mechanism of ZnO hierarchical structure based gas sensor. Such a detailed study may open up an avenue to fabricate sensor which achieve high sensitivity, good selectivity and long-term stability, making it a promising candidate for transformer oil monitor.
关键词： ZnO,sensitivity,gas sensors,hierarchical structures,stability,gas sensing mechanism,selectivity
更新于2025-09-10 09:29:36
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Highly Sensitive Ammonia Sensors Based on Ag-Decorated WO <sub/>3</sub> Nanorods
摘要： In this paper, WO3 nanorods are successfully synthesized via a one-step hydrothermal method, and then, silver nanoparticles are deposited on the WO3 surface by in situ photoreduction method to obtain Ag/WO3 gas sensitive materials. WO3 and Ag/WO3 are characterized by scanning electron microscope techniques, transmission electron microscope, and X-ray diffraction. The experimental results indicated that Ag nanoparticles have an important effect on the gas response of WO3 . The Ag/WO3 sensor greatly improves the selectivity and response compared to the traditional WO3 sensor; the response is 300 for 100 ppm ammonia when the Ag/WO3 sensor operates at the optimum operating temperature. The Ag/WO3 sensor can respond to 50 ppb ammonia.
关键词： nanoparticle,One-step hydrothermal method,gas sensing mechanism,high sensitivity
更新于2025-09-10 09:29:36
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Significant Enhancement of Hydrogen-Sensing Properties of ZnO Nanofibers through NiO Loading
摘要： Metal oxide p-n heterojunction nano?bers (NFs) are among the most promising approaches to enhancing the ef?ciency of gas sensors. In this paper, we report the preparation of a series of p-NiO-loaded n-ZnO NFs, namely (1?x)ZnO-xNiO (x = 0.03, 0.05, 0.7, 0.1, and 0.15 wt%), for hydrogen gas sensing experiments. Samples were prepared through the electrospinning technique followed by a calcination process. The sensing experiments showed that the sample with 0.05 wt% NiO loading resulted in the highest sensing performance at an optimal sensing temperature of 200 ?C. The sensing mechanism is discussed in detail and contributions of the p-n heterojunctions, metallization of ZnO and catalytic effect of NiO on the sensing enhancements of an optimized gas sensor are analyzed. This study demonstrates the possibility of fabricating high-performance H2 sensors through the optimization of p-type metal oxide loading on the surfaces of n-type metal oxides.
关键词： ZnO,NiO loading,sensing mechanism,gas sensor,nano?ber,p-n heterojunction
更新于2025-09-09 09:28:46