SO2 Sensor Research Articles

Scalable Melt Polymerization Synthesis of Covalent Organic Framework Films for Room Temperature Low-Concentration SO2 Detection.

The development of highly efficient sensors for low-concentration SO2 at room temperature is important for human health and fine chemistry, but it still faces critical challenges. Herein, a scalable olefin-linked covalent organic framework (COF) with an ultramicroporous structure and abundant binding sites is first developed as the SO2 sensing material. The COF can adsorb SO2 of 220 cm3/g at 1 bar and 40 cm3/g at 0.01 bar and 298 K, surpassing all reported COFs. The computational and kinetic adsorption studies deeply unveil the selective adsorption mechanism for low-concentration SO2. Furthermore, the multicomponent gas mixture breakthrough experiments confirm that the COF can specifically capture low-concentration (2000 ppm) SO2. We innovated a melt polymerization technology to fabricate COF films with adjustable substrates and film thicknesses. COF films are directly grown on the interdigital electrodes to prepare the SO2 sensor device, which possesses a low detection limit (86 ppb) and excellent selectivity for SO2 in the presence of 10 other potentially interfering gases. Compared to other reported SO2 sensors, its overall performance is among the top. Prominently, the sensor maintains a stable output signal for more than two months, and recovery can be easily achieved by simply purifying nitrogen at room temperature without heating. This study marks the first use of COFs for SO2 sensing, opening new possibilities for COFs in the detection of low-concentration toxic gases and manufacturing gas sensor devices.

Enhancing SO2 Sensing Performance of a Fuel Cell-Type Sensor with N-Doped Cu/CNT Aerogel Electrode and COF/Nafion Electrolyte.

Sulfur dioxide (SO2) is a common environmental pollutant with significant hazards. However, sensors for SO2 real-time monitoring at room temperature often face problems such as a poor response and sluggish recovery. In this work, a fuel cell-type gas sensor based on nitrogen-doped carbon nanotube (CNT) aerogels loaded with Cu particle electrode material and COF/Nafion composite electrolyte was developed, which exhibited excellent SO2 sensitivity and fast response/recovery. The aerogel scaffold provided a high specific surface area and high electrical conductivity, and Cu particles provided good catalytic activity to SO2. In addition, N doping further enhanced the SO2 capture capability and conductivity of the electrode material. For electrolyte construction, covalent organic framework (COF) nanosheets were synthesized by a bottom-up approach and blended with Nafion to prepare the COF/Nafion membrane; the composite membrane showed higher proton conductivity. Owing to these advantages, the fuel cell-type sensor exhibited an outstanding response of -3008.5 nA to 50 ppm of SO2 with a rapid response time (35 s) and recovery time (77 s). Moreover, the rigid nanochannels of COF nanosheets improved the water retention properties of the electrolyte; this will help to simplify the structure of fuel cell-type sensors and provide a significant stimulus for their miniaturization. Based on the great sensing performance, a fuel cell-type SO2 sensor is integrated into a portable detector and evaluated in the context of dynamic environmental monitoring. The results show that the fuel cell-type sensor with the carefully designed electrode and electrolyte will have great potential in environmental monitoring and safety assurance.

Theoretical Investigation of Rhodium-Decorated Gallium Nitride Nanotubes for Sulfur Hexafluoride Decomposition Products Sensing and Scavenging Applications.

Gas-insulated switchgear (GIS) plays an important role as a modern power distribution device in power plants and power stations, which is commonly filled with SF6 insulating gas. During the equipment operation, the inevitable partial discharge causes SF6 to be broken down into gas (SF4, SOF2, SO2, and H2S), which degrades the insulation performance of the GIS. This paper is devoted to the detection of partial discharge and the removal of SF4 and SOF2, which are not conducive to insulation, by exploring new gas-sensing materials for characteristic gas detection. Based on first-principles calculation, on the one hand, the most stable adsorption configurations of rhodium-decorated gallium nitride nanotubes (Rh-GaNNTs) and gas adsorption systems were obtained. On the other hand, the doping and adsorption mechanisms were analyzed by band structure, density of states, deformation charge density, and molecular orbital theory. Subsequently, the gas-sensitive performance of Rh-GaNNTs for these four impurity gases was evaluated by analyzing the sensing response and recovery time. The adsorption stability and recovery time of Rh-GaNNTs to these gases are ranked as SF4 > SOF2 > SO2 > H2S; the order of influence of gas adsorption on sensitivity response is H2S > SO2 > SF4 ≈ SOF2. Calculation results show the potential of Rh-doped surfaces as reusable H2S and SO2 sensors and suggest their use as gas scavengers to remove SF4 and SOF2, especially SOF2.

Room-temperature self-calibrating sensor based on CsPbBr3/SnO2 for detecting low-concentration sulfur dioxide

Sulfur dioxide (SO2) is a colorless toxic gas, and accurate monitoring of its concentration is important for safety. However, accuracy is often interfered by humidity. To address the issues, in this work, a self-calibrating SO2 sensor based on CsPbBr3/SnO2 was prepared, the sensor exhibited an excellent response to parts per billion (ppb) levels of SO2 at room temperature, which is rarely achieved by other SO2 sensors. The response sensitivity of the sensor to 600 ppb SO2 reached up to 0.53 with response/recovery times of 17/285 s. In addition, the CsPbBr3/SnO2-based SO2 gas sensor showed a low detection limit, good reproducibility, and high selectivity. Moreover, theoretical calculations show that the gas recognition mechanism is attributed to the significant changes in the band structure and density of states of the heterojunction materials CsPbBr3/SnO2 after gas adsorption, thereby altering the charge carrier transport behavior and electrical properties. A self-calibrating algorithm MobileNetV2 was employed to eliminate humidity interference and effectively identify low-concentration SO2 in humid environments, and the recognition accuracy rate is 0.85. This work demonstrates the production of a high-performance SO2 gas sensor, and provides an effective method to eliminate the interference of humidity, making it significant in environmental monitoring and air quality control.

GeC monolayer: A promising 2D material for reusable SO2 and NO2 gas sensor with high sensitivity

Gas sensors are crucial in various fields such as environmental monitoring, industrial production, and healthcare due to their ability to detect harmful gases in real-time. This study investigates GeC monolayer as a potential material for gas sensors targeting sulfur-containing toxic gases (SO2, H2S, SF4) and nitrogen-containing toxic gases (NO, NH3, NO2). The electronic and adsorption properties of GeC monolayer were explored using density functional theory (DFT) calculations. The adsorption of SO2 and nitrogen dioxide significantly affects the band structure and work function of GeC monolayer, indicating that compared to other toxic gases, GeC monolayers exhibit higher sensitivity and selectivity towards SO2 and NO2. The electron localization function analysis indicates that the adsorption process is characterized by physical adsorption. In addition, GeC monolayer exhibits good desorption behavior towards SO2 and NO2 at room temperature. These findings suggest that GeC monolayer is a promising material for developing efficient gas sensors for detecting SO2 and NO2.

GeP3 monolayer as a promising 2D sensing materials in detecting SO2, H2S, SOF2 and SO2F2

The detection of SF6 decomposition components using gas-sensitive sensors is significantly important for characterizing internal insulation failures and assessing the operational status of SF6 gas-insulated equipment. In this paper, the adsorption properties of GeP3 monolayers for SO2, H2S, SOF2 and SO2F2 gases were investigated based on density functional theory. Four gas adsorption systems were constructed, and the adsorption mechanisms and sensing characteristics of GeP3 monolayers on target gases were investigated by calculating parameters such as adsorption energy, charge transfer, density of states, and recovery time, along with their potential application as resistive gas sensors and field-effect transistor sensors. It is demonstrated that GeP3 monolayers were suitable for the detection of SO2, H2S, SOF2 and SO2F2 gases, all of which exhibited good chemisorption with adsorption energies of −1.36 eV, −0.78 eV, −1.82 eV and −2.91 eV, respectively. The adsorption of SO2 and H2S is found to cause a significant change in the conductivity of the GeP3 monolayers, and desorption is achieved at the optimal operating temperature in only 54.428 s and 10.686 s, respectively. Also the adsorption of SOF2 and SO2F2 can make the work function of the GeP3 monolayers significantly larger. Consequently, the GeP3 monolayers have the potential to be used as a resistive gas sensor for SO2 and H2S gases, or as a field effect transistor sensor for SOF2 and SO2F2 gases. This study provides theoretical guidance for the development of GeP3-based sensors for monitoring the insulation status and operational conditions of SF6 gas-insulated equipment.

Highly sensitive MXene-based SO2 sensor enhanced by modification of SnO2 at room temperature

Highly sensitive MXene-based SO2 sensor enhanced by modification of SnO2 at room temperature

A Dual Electrode Mixed Potential SO₂ Sensor With Humidity Self-Correction Function Utilizing Multiple Linear Regression Model

A Dual Electrode Mixed Potential SO₂ Sensor With Humidity Self-Correction Function Utilizing Multiple Linear Regression Model

Pressure-Compensated Fiber-Optic Photoacoustic Sensors for Trace SO2 Analysis in Gas Insulation Equipment.

A high-sensitivity fiber-optic photoacoustic sensor with pressure compensation is proposed to analyze the decomposition component SO2 in high-pressure gas insulation equipment. The multiple influence mechanism of pressure on photoacoustic excitation and cantilever detection has been theoretically analyzed and verified. In the high-pressure environment, the excited photoacoustic signal is enhanced, which compensates for the loss of sensitivity of the cantilever. A fiber-optic F-P cantilever is utilized to simultaneously measure static pressure and dynamic photoacoustic wave, and a spectral demodulation method based on white light interference is applied to calculate the optical path difference of the F-P interferometer (FPI). The real-time pressure is judged through the linear relationship between the average optical path difference of FPI and the pressure, which gives the proposed fiber-optic photoacoustic sensor the inherent advantages of being uncharged and resistant to electromagnetic interference. The average optical path difference of FPI is positively related to pressure, with a responsivity of 0.6 μm/atm, which is based on changes in the refractive index of gas. In the range of 1-4 atm, the SO2 sensor has a higher detection sensitivity at high-pressure, which benefits from the pressure compensation effect. With the pressure environment of gas insulation equipment at 4 atm as the application background, the SO2 gas is tested. The detection limit is 20 ppb with an averaging time of 400 s.

Electrospun rGO-PVDF/WO3 composite fibers for SO2 sensing

Developing highly selective and sensitive SO2 sensors is essential due to the excessive presence of SO2 in the environment which can cause respiratory illness and acid rain. Semiconducting metal oxides are the materials most used for the development of SO2 sensors; however, they still suffer from sensitivity, selectivity, low-temperature operation, low detection limit, and slow response/recovery time for real-field applications. In this work, rGO-PVDF/WO3 composite fibre-based sensors are developed via electrospinning technique. The electrospun rGO-PVDF/WO3 were characterized for their structural morphology, thermal stability, crystal structure, and their SO2 sensing capability. The results show that the electrospun rGO-PVDF/WO3 sensor (containing 10 mL GO) leads the most improved SO2 sensing performance of all tested sensors in this work, with a response of 11.08 and 22.06 at SO2 concentrations of 60 and 80 ppm, respectively. The 10 mL-rGO-PDVF/WO3 composite nanofibers also demonstrated good selectivity and stability for SO2. The improvement in gas sensitivity is due to the synergistic effect of forming an ohmic contact between the rGO nanosheets, PVDF fibers, and the WO3 nanograins. The good surface properties such as high surface area (10.64 m2/g) and porous structure of 10 mL-rGO-PDVF/WO3 composite nanofibers have also contributed to the SO2 gas sensing performance. The results show that the composite nanofibers rGO-PVDF/WO3 can be used to detect low concentrations of SO2 and could be used to monitor the environment.

Thermal decomposition and combustion of interior design materials

Research findings on the patterns of thermal decomposition and combustion are reported for widely used interior design materials. The experiments were conducted using a hardware and software system including a thermogravimetric analyzer (to record the characteristics of thermal decomposition), a gas analyzer (with H2, CH4, H2S, SO2, CO and CO2 sensors) and a high-speed camera (to record the characteristics of ignition and combustion). The temperature of the oxidizing medium ranged from 500 to 900°C to investigate the conditions of thermal decomposition initiation and sustained combustion. It was established that the highest concentrations of toxic emissions were typical of the combustion of polypropylene at a maximum temperature of the oxidizing medium (900°C). Wood showed the shortest ignition delay time and the longest duration of combustion. The experimental data were used for a physical problem statement and mathematical model of heat and mass transfer to explore the thermal decomposition and combustion of interior design materials in different rooms. A comparison of the experimental findings with the mathematical modeling results validates the developed model. The growth rates of carbon monoxide and carbon dioxide concentrations were determined for construction (wooden) and interior design (polymer) materials. The maximum concentrations of CO and CO2, and the minimum times taken to reach their threshold values corresponded to wood and polyvinyl chloride panels. This research provides a deeper insight into the thermal decomposition of a wide range of fuels and the formation of gaseous pyrolysis products of these fuels. The results obtained can be used to evaluate the toxicity of construction and interior design materials during compartment fires as well as to estimate the safe egress time and risks involved in the process. They can also serve as a database for the development and testing of mathematical models describing fire outbreaks and propagation in confined spaces.

Adsorption of SF6 decomposition gases (H2S, SO2 and SOF2) on TM (Pd and Pt) modified monolayer ZrS2: A DFT study

Fast and effective detection of SF6 gas decomposition products is essential. In this study, the adsorption behaviors of H2S, SO2 and SOF2 on Pd-ZrS2 and Pt-ZrS2 monolayers were analyzed using density-functional theory (DFT), and the electronic properties of the different adsorption systems and their sensing properties were discussed in depth. The results show that the Pd and Pt modifications significantly improve the surface activity of the intrinsic ZrS2 monolayers, giving them better adsorption and sensing properties. The reasonable adsorption energies and significant sensitivity differences suggest that the Pd(Pt)-ZrS2 monolayers may be potential candidates for H2S, SO2 and SOF2 sensors. This study provides theoretical guidance for the prospective application of Pd(Pt)-ZrS2 in the operational condition assessment of GIS equipment.

Layer-tunable synthesis of tetragonal Pr-doped SnO2 nanoplates for enhanced sensitive SO2 sensor

Nowadays SnO2 is widely used in manufacturing gas sensors for the detection of toxic and harmful gases such as SO2. However, SnO2 sensor still has the drawbacks of long recovery/response time and low response value. In this experiment, layer-tunable synthesis of tetragonal Pr-doped SnO2 nanoplates are prepared by a feasible hydrothermal method. Observation at SEM reveals that the layer number increases and the interlayer spacing reduces with the increase of doping ratio of Pr (1, 3, 5 mol%). The gas sensing performance show that the three layer tetragonal structure of 1 mol% Pr-doped SnO2 sample with the extended interlayer spacing exhibits outstanding gas sensing performance to 5 ppm SO2 gas at 300℃, including excellent gas response (Ra/Rg = 2.4), fast gas adsorption and desorption equilibrium (15 s/16 s). This work reveals the significance of the layer number and interlayer spacing on the gas sensing characteristics, and the strategy of Pr dopant will promote the widespread application of SnO2 nanomaterials in SO2 gas sensors to figure out severe environmental problems.

Janus HfSSe monolayer: a promising candidate for SO2 and COCl2 gas sensing

Janus monolayers based on transition metal dichalcogenides have garnered significant interest as potential materials for nano electronic device applications due to their exceptional physical and electronic properties. In this study, we investigate the stability of the Janus HfSSe monolayer using ab initio molecular dynamics simulations and analyze the electronic properties in its pristine state. We then examine the impact of adsorbing toxic gas molecules (AsH3, COCl2, NH3, NO2, and SO2) on the monolayer’s structure and electronic properties, testing their adsorption on different active sites on top of hafnium, selenium, and sulfur. The sensitivity of the gas molecules is quantified in terms of their adsorption energy, with the highest and lowest energies being observed for SO2 (−0.278 eV) and NO2 (−0.095 eV), respectively. Additionally, we calculate other properties such as recovery time, adsorption height, Bader charge, and charge difference density to determine the sensitivity and selectivity of the toxic gas molecules. Our findings suggest that the Janus HfSSe monolayer has the potential to function as SO2 and COCl2 gas sensor due to its high sensitivity for these two gases.

Investigation of the electronic and optical properties of bilayer CdS as a gas sensor: first-principles calculations.

We utilised first-principles computations based on density functional theory to investigate the optical and electronic properties of bilayer CdS before and after the adsorption of gas molecules. Initially, we examined four candidate adsorption sites to determine the best site for adsorbing CO, CO2, SO2, H2S, and SO. In order to achieve the optimal adsorption configurations, we analysed the adsorption energy, distance, and total charge. Our findings reveal that the CdS bilayer forms a unique connection between the O and Cd atoms, as well as the S and Cd atoms, which renders it sensitive to SO2, H2S, and SO through chemical adsorption, and CO and CO2 through strong physical adsorption. The adsorption of gas molecules enhances the optical properties of the CdS bilayer. Consequently, the CdS bilayer proves to be a highly efficient gas sensor for SO2, H2S, and SO gases.

Reduced graphene oxide (rGO) and 5, 10, 15, 20-tetra-p-tolyl-21H, 23H-porphine (TPTP) composite: highly reproducible and repeatable chemiresistive SO2 sensor

Reduced graphene oxide (rGO) and 5, 10, 15, 20-tetra-p-tolyl-21H, 23H-porphine (TPTP) composite: highly reproducible and repeatable chemiresistive SO2 sensor

All-optical photoacoustic detection of SF6 decomposition component SO2 based on fiber-coupled UV-LED

An all-optical photoacoustic sensor for measuring the concentration of SF6 decomposition derivative SO2 was designed, whose detection limit was in the order of ppb-level. An UV-fiber and a single-mode fiber were utilized to transmit excitation light and probe light, respectively. The technical scheme of all-optical gas sensing has realized the competitive advantages of long-distance detection and anti-electromagnetic interference. As an UV-LED was the excitation light, the challenge of designing all-optical SO2 sensor was to effectively couple UV-LED with large divergence angle into an UV- fiber. Theoretical calculation and experiment have proved that the lens assembly as an effective strategy to realize the efficient coupling and beam collimation, which can achieve high excitation power and low solid photoacoustic background interference. The lens assembly with high focusing property was the key to improve the signal-to-noise ratio (SNR) by 5.2 times. To detect photoacoustic pressure with high sensitivity, a fiber optic cantilever acoustic sensor based on F-P interference was designed. Based on the demodulation algorithm of white light interference, dynamic cavity length of F-P was demodulated with high-resolution. Allan-Werle analysis result indicate that the detection limit of SO2 gas was 48 ppb with an averaging time of 100 s

Fuel cell type SO2 sensor based on Cu/CF-N sensing electrode and Nafion proton conductor at room temperature

In this work, nitrogen doped carbon fiber loaded copper (Cu/CF-N) sensing electrode and Nafion proton conductor are used to fabricate fuel cell type gas sensors that realize fast response/recovery for SO2 detection at room temperature. This is the first time that this type of sensor has been used to detect SO2. We investigated the effect of Cu content on sensors’ performance, and found that the Cu (20 wt%)/CF based sensor exhibited the highest response. This can be attributed to the optimal Cu content, which exposes the most active sites. Moreover, nitrogen was doped into electrode material to further improve the performance. Nitrogen atoms enhance the conductivity of the material and its ability to adsorb SO2. These are confirmed by the complex impedance measurement and TPD analysis. The upgraded Cu/CF-N fuel cell type gas sensor showed a response of − 435.6 nA to 50 ppm SO2 and a low detection limit of 500 ppb. Significantly, the Cu/CF-N sensor demonstrated short response time (44 s) and recovery time (87 s) at room temperature. Furthermore, with the advantages of no power consumption, excellent selectivity and good repeatability, the fuel cell type gas sensors have broad prospects in the field of room temperature gas detection.

Adsorption of sulfur-containing contaminant gases by pristine, Cr and Mo doped NbS2 monolayers based on density functional theory

The adsorption and sensor performance of hazardous gases containing sulfur (SO2, H2S and SO3) on pristine, Cr and Mo doped NbS2 monolayers (Cr-NbS2 and Mo-NbS2) were investigated in detail based on density functional theory. The comparative analysis of the parameters such as density of states, adsorption energy, charge transfer, recovery time and work function of the systems showed that the pristine NbS2 monolayer have poor sensor performance for sulfur-containing hazardous gases due to weak adsorption capacity, insignificant charge transfer and insignificant changes in electronic properties after gas adsorption on the surface. After doping with Cr atoms, the adsorption performance of Cr-NbS2 was significantly improved, and it can be used as a sensor for SO2 and H2S gases and as an adsorbent for SO3 gas. The adsorption performance of Mo-NbS2 is also significantly improved by doping with Mo atoms, and it can be used as a sensor for H2S gas and as an adsorbent for SO2 and SO3 gas. Therefore, Cr-NbS2 and Mo-NbS2 are revealed to be sensing or elimination materials for the harmful gases containing sulfur (SO2, H2S and SO3) in the atmosphere.

Highly Selective Chemiresistive SO2 Sensor Based on a Reduced Graphene Oxide/Porphyrin (rGO/TAPP) Composite

AbstractThe emergence of toxic pollutants due to heavy human intervention in the ecosystem causes serious environmental problems. Therefore, sensors based on material having a strong affinity towards specific environmental gaseous pollutants are urgently needed. The present study deals with chemiresistive gas sensors for the detection of sulfur dioxide (SO2) based on a composite of reduced graphene oxide (rGO) and 5,10,15,20-tetrakis(4-aminophenyl) porphyrin (TAPP). The improved Hummers method was used to synthesize graphene oxide (GO); it was further thermally reduced to rGO. The pattern of the copper electrode was coated on glass slides with a shadow mask using thermal evaporation. Then, GO was drop-cast between the two copper electrodes, thermally reduced to obtain rGO, and then modified by TAPP. The spectroscopic, structural, morphological, electrical, and optical studies were carried out using Fourier transform infrared spectroscopy, x-ray diffraction, Raman spectroscopy, atomic force microscopy, field emission scanning electron microscopy, current–voltage (I–V) and UV–visible spectroscopy, respectively. The developed sensor shows high selectivity towards SO2 gas analytes among exposed gaseous analytes. It exhibited reproducible response from 50 ppm to 200 ppm with enhanced repeatability at 50 ppm. The rGO/TAPP sensor exhibited a significant response (57 s) and recovery time (61 s), with a 5 ppm limit of detection. Graphical Abstract