H2S Sensor Research Articles

Design of a Dual-Phase TiN-WN electrochemical sensor for H2S detection

Electrode materials are pivotal in fuel cell-based gas sensors, yet conventional Pt-based catalysts often suffer from limitations in electronic structure and stability, restricting the practical application of H2S detection. Here, we introduce a Pt catalyst supported by a titanium-tungsten nitride (TiN-WN) composite for an electrochemical H2S sensor. Leveraging the multilevel electron transfer of the Pt/TiN-WN composite, this sensor achieves electron accumulation on the Pt surface, yielding enhanced conductivity and abundant active sites for high H2S sensitivity. It achieves a response current of 12.2 µA, 1.7 times that of Pt/C (7.1 µA), and demonstrates excellent linearity (R2 = 0.999), stability over repeated tests, and robust anti-interference capability. These findings mark a significant advancement in H2S sensing, offering a reliable solution for real-time monitoring and addressing key limitations of current systems.

Chemoresistive H2S sensor based on PANI/TiO2/CuCl2 nanocomposite impregnated conductive fabric using TOPSIS and Taguchi method

Abstract Conductive polymer/metal oxide nanocomposites have been widely used for chmoresistive gas sensors. PANI/TiO2/CuCl2 nanocomposite(PTCN) impregnated conductive fabric was prepared by in-situ synthesis method. To improve the performance of PTCN impregnated fabric for detecting H2S gas, Taguchi orthogonal array(TOA) is used to experimental design, and best values of factors affecting to the sensing performance are determined using Technique for order preference by similarity to ideal solution (TOPSIS) and Taguchi optimization method. PTCNs were charactierized by SEM, XRD, FTIR. The sensing performances of the proposed sensor such as linear detection range, sensitivity, repeatability and effect of humidity for hydrogen sulfide gas were evaluated.

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.

Multifunctional Au–Ag NCs for luminescence and colorimetric double signal sensing of H2S and catalytic reduction of nitrophenol

In this study, the N-Acetyl-l-Cysteine (NAC)-capped gold and silver bimetallic nanoclusters (NAC@Au–Ag NCs) was synthesized by reflux method. Due to the silver effect, the NAC@Au–Ag NCs exhibited strong photoluminescence at far-red/near-infrared regions and better catalytic performance than Au or Ag NCs. Upon addition of H2S, the Au–Ag NCs exhibited obvious fluorescence quench and color changes through the generation of metal sulfides and a static quenching process. The Au–Ag NCs displayed a wide linear luminescence response for H2S (18.5–217 μmol/L) with a detection limit of 0.269 μmol/L. Moreover, the visible color of Au–Ag NCs changed from white to brown-yellow along with increased H2S, the corresponding RGB values also displayed good linearity with the concentration of H2S (90.1–678 μmol/L). Notably, the fabrication of test strips provided a convenient and intuitive tool to screen the freshness of eggs by the color change of test strips. Au–Ag NCs could be used for living HeLa cells bioimaging and recognition of H2S abnormalities. Furthermore, it can be used as a catalyst to reduction of nitrophenols (NPhs), specific included 2NP, 3NP and 4NP. The reaction was regarded as a pseudo-first-order kinetic reaction due to the presence of excess NaBH4. At 298K, the catalytic rate constants(k) of 2NP, 3NP and 4NP were 0.1754 min−1, 0.1734 min−1 and 0.2782 min−1, respectively. The NAC@Au–Ag NCs catalyst still showed good catalytic activity and reusability after five cycles. Therefore, this study developed a H2S sensor for food samples and biological systems. And this nanocatalyst had great application potential for removed the nitrophenol pollutants in water.

Chemiresistive room temperature H2S sensor based on CunO nanoflowers fabricated by laser ablation

Hierarchical CunO nanoflowers were synthesized through the laser ablation of a CuO target in NaOH solutions for room-temperature (27 ℃) H2S detection. Notably, the pH value of NaOH solutions influenced both the micro-morphologies and compositions of the CunO products, as evidenced by XRD, XPS, SEM and TEM. In high pH solutions, the specific surface area of the CunO products increased, their thickness decreased, and the Cu2O content diminished, resulting in enhanced sensitivity, selectivity and stability of the CunO products’ response to H2S. Notably, the pH14# sample synthesized using an NaOH solution with a pH value of 14 featured pure CuO nanoflowers comprising slightly curled nanosheets with a thickness of approximately 10 nm. This sensor demonstrated excellent H2S sensing performance at room temperature, exhibiting a response value of 1.17 for 10 ppb H2S, along with high selectivity and good long-term stability. However, after exposure to H2S, the resistance of the sensor did not recover to its baseline in air at room temperature. Thermogravimetry results revealed that a temperature of 300 °C was effective for recovery of the sensor. Consequently, the operation temperature of the pH14# sensor was controlled using a micro-hotplate. In the pulse heating mode, the sensor’s response to 100 ppb H2S was 1.5, with a response time of 135 s and a recovery time of 137 s.

High-Performance H2S Sensors to Detect SF6 Leakage.

Detecting H2S in oxygen-deficient conditions is vital for identifying leaks in SF6-insulated electrical equipment. Current infrared-based detection methods are expensive and sensitive to environmental conditions, highlighting the necessity for cost-effective and stable gas sensors. Existing gas sensors based on semiconducting metal oxides (SMOXs) are limited by redox reactions with oxygen and require high operating temperatures. Here, we introduce a room-temperature (RT) H2S sensor for oxygen-deficient environments using the intrinsic conducting two-dimensional (2D) metal-organic framework (MOF), Co1.8Ni1.2(hexaiminotriphenylene)2 [Co1.8Ni1.2(HITP)2], overcoming the limitations of SMOX gas sensors. Remarkably, Co1.8Ni1.2(HITP)2 sensors exhibit exceptional selectivity for H2S with negligible cross-responses and a sensitivity drift of less than 4.13% in an SF6 atmosphere over 60 days. The Co1.8Ni1.2(HITP)2 gas sensor shows significant promise for real-time and stable monitoring of H2S gas in oxygen-deficient environments.

Unveiling the potential of newly synthesized 2D TMCC monolayer for H2S gas sensing: A DFT study

The 2D monolayer of transition metal carbo-dichalcogenide (TMCC) has been recently synthesized from its bulk form. It is a unique blend of MXenes and transition metal dichalcogenides (TMDCs), offering superior properties compared to its individual parent components. TMCC has not yet been explored for its potential in gas sensing applications, motivating us to investigate its performance for detecting H2S gas molecule. The pristine monolayer of TMCC (Nb2S2C) exhibited weak H2S adsorption energy (-0.18 eV), leading to low sensitivity, poor selectivity, underscoring surface modification. The decoration strategy was incorporated by considering transition metal (TM) atoms like Ti, Co, Cu, Pd and Ag. Ti and Co decorated TMCC showed superior H2S gas sensing performance. Ti showed maximum binding energy (-5.44 eV) followed by Co (-4.91 eV). The adsorption energy of H2S on Ti and Co decorated TMCC were comparable having values of -1.08 eV and -1.09 eV respectively while showing respective practical recovery time of 6 s and 8.5 s at 350 K, respectively. The improved adsorption mechanism is due to orbital interaction and charge transfer. Work function sensitivity and thermal stability upto 400 K was assessed. The study shows Ti and Co decorated TMCC monolayer as a suitable candidate for H2S sensing, inspiring experimentalists to fabricate TMCC-based H2S sensors.

2D electrodeposition assembly of Cu/Cu2O nanoarrays for low temperature H2S sensing

Ultra-sensitive hydrogen sulfide (H2S) detection technology at low temperatures provides critical support for the application of one-time alert systems under extreme conditions, ensuring reliable monitoring of H2S in low-temperature environments and enhancing safety and practicability. In this study, we developed a novel low-temperature H2S sensor based on Cu/Cu2O nanoarrays, prepared through a combination of 2D electrodeposition in situ assembly and the hydrothermal method. The heterointerface between Cu nanowires and Cu2O nanocubes presents a high barrier, which can be modulated to zero through the formation of continuous CuxS conductive channels via the vulcanization reaction, thereby achieving excellent sensitivity and selectivity towards H2S at low temperatures. At freezing temperatures and low H2S concentrations (≤20 ppm), the sensors show ideal recovery and reasonable sensitivity (R=150 to 10 ppm H2S at 0 °C). However, the response significantly increases (R=5624 at 10 ppm H2S at 50 °C) and recovery is lost under reversed conditions. First-principles calculations have confirmed that the enhanced H2S adsorption at the heterointerface is the primary reason for the robust response observed at 0 °C. Experimental results demonstrate that the Cu/Cu2O nanoarrays were capable of rapid detection of H2S at low temperatures through modulation of heterointerface barriers.

In Situ Synthesis of Hierarchical Co(CO3)0.5(OH)·0.11H2O@ZIF-67/WO3 With High Humidity Immunity and Response to H2S Sensing.

H2S gas sensors with facile preparation, low detection limits, and high selectivity are crucial for environmental and human health monitoring. However, it is difficult to maintain a high response of H2S gas sensors under high humidity in practical applications. To face this dilemma, a layer-by-layer growth method is applied to in situ prepare a nanostructured Co(CO3)0.5(OH)·0.11H2O/WO3 coated by a hydrophobic hierarchical ZIF-67 as the H2S sensor. This novel composite exhibits excellent humidity immunity without sacrificing the excellent sensitivity and selectivity of H2S. At a low operating temperature of 90°C, a remarkable response value of 1052.3 to 100ppm H2S has been achieved, which is 779 and 9.36 times higher than that of pure WO3 and Co(CO3)0.5(OH)·0.11H2O/WO3, respectively. More importantly, an 82.2% relative response value remains at a high humidity of 75%RH. The sensing mechanisms are investigated using gas chromatography-mass spectrometry (GC-MS), which revealed that the reaction products are H2O and SO2. The high humidity immunity and fast response of the Co(CO3)0.5(OH)·0.11H2O@ZIF-67/WO3 demonstrate the layer-by-layer in situ synthesis method holds the potential application for the development of high-performance WO3-based H2S sensors.

Resistance-driven low power H2S sensors based on MWCNT@CuO heterojunction

Resistance-driven low power H2S sensors based on MWCNT@CuO heterojunction

Chemiresistive NH3 and H2S sensors based on thin films of vitamin B12 derivatives

Despite the large number of materials, e.g. semiconducting oxides, carbon nanomaterials, conducting polymers and others, that are used as active layers of chemiresistive sensors to ammonia and hydrogen sulfide, the search for new materials remains an urgent task. Special attention is paid to the search for environmentally friendly materials. Corrinoids are naturally occurring coordination complexes consisting of a central cobalt ion and a tetrapyrrole ligand called a corrin ring. Cobalamins and their derivatives are widely used as active layers of optical and electrochemical sensors. At the same time, vitamin B12 derivatives have not been studied as active layers of chemiresistive gas sensors. In this work, films of two vitamin B12 derivatives, viz. dicyanocobyrinic acid heptabutyl ester (DC) and its aquacyano form, aquacyanocobyrinic acid heptabutyl ester (AC), deposited by spin coating and drop casting techniques onto interdigitated electrodes, were tested for the first time as active layers of chemiresistive sensors for the detection of low concentrations of ammonia and hydrogen sulfide (1–50 ppm) in air. It was shown that films of both vitamin B12 derivatives demonstrated reversible sensor response to NH3 and H2S at room temperature. The limit of detection (LOD) of H2S was 0.1 ppm for both vitamin B12 derivatives, while LOD of ammonia was noticeably lower (0.06 ppm) in the case of AC films than in the case of DC films (0.4 ppm). Both sensors demonstrated a fairly low regeneration time, which did not exceed 180 s for 5 ppm of NH3 and 185 s for 5 ppm of H2S.

Conductometric H2S Sensors Based on TiO2 Nanoparticles.

High-performance hydrogen sulfide (H2S) sensors are mandatory for many industrial applications. However, the development of H2S sensors still remains a challenge for researchers. In this work, we report the study of a TiO2-based conductometric sensor for H2S monitoring at low concentrations. TiO2 samples were first synthesized using the sol-gel route, annealed at different temperatures (400 and 600 °C), and thoroughly characterized to evaluate their morphological and microstructural properties. Scanning electronic microscopy, Raman scattering, X-ray diffraction, and FTIR spectroscopy have demonstrated the formation of clusters of pure anatase in the TiO2 phase. Increasing the calcination temperature to 600 °C enhanced TiO2 crystallinity and particle size (from 11 nm to 51 nm), accompanied by the transition to the rutile phase and a slight decrease in band gap (3.31 eV for 400 °C to 3.26 eV for 600 °C). Sensing tests demonstrate that TiO2 annealed at 400 °C displays good performances (sensor response Ra/Rg of ~3.3 at 2.5 ppm and fast response/recovery of 8 and 23 s, respectively) for the detection of H2S at low concentrations in air.

Pt/Ti3C2 electrode material used for H2S sensor with low detection limit and high stability

Traditional Pt/C electrode materials are prone to corrosion and detachment during H2S detection, leading to a decrease in fuel cell-type sensor performance. Here, a high-performance H2S sensor based on Pt loaded Ti3C2 electrode material with -O/-OH terminal groups was designed and prepared. Experimental tests showed that the Pt/Ti3C2 sensor has good sensitivity (0.162 μA/ppm) and a very low detection limit to H2S (10 ppb). After 90 days of stability testing, the response of the Pt/Ti3C2 sensor shows a smaller decrease of 2% compared to that of the Pt/C sensor (22.9%). Meanwhile, the sensor also has high selectivity and repeatability. The density functional theory (DFT) calculation combined with the experiment results revealed that the improved H2S sensing mechanism is attributed to the fact that the strong interaction between Pt and Ti3C2via the Pt-O-Ti bonding can reduce the formation energy of Pt and Ti3C2, ultimately prolonging the sensor's service life. Furthermore, the catalytic property of Pt can decrease the adsorption energy and dissociation barrier of H2S on Pt/Ti3C2 surface, greatly enhance the ability to generate protons and effectively transfer charges, realizing good sensitivity and high selectivity of the sensor. The sensor works at room temperature, making it very promising in the field of H2S detection in future.

Fe2O3 Modified ZnO Thick Film Resistors as H2S Sensor

Fe2O3 Modified ZnO Thick Film Resistors as H2S Sensor

Thermal-aware device design of low-power H2S sensors using Joule-heated Au nanosheet

We demonstrated Joule-heated Au nanosheet H2S sensors for low-power operation. We confirmed that low temperature regions in the Joule-heated Au nanosheet caused lower response and recovery characteristics than uniformly heated Au nanosheets. By using Pt electrodes, which has lower thermal conductivity than Au, heat dissipation to the electrodes could be suppressed, resulting in lower power consumption and faster recovery characteristics. We then discussed the optimal sensor structure by developing an analytical model of electrical and thermal resistances. We introduced semi-elliptical intermediate electrodes between the channel and pad electrodes to efficiently suppress the heat dissipation, demonstrating that the optimal channel length and thermal conductivity of the intermediate electrode κ int exist depending on the channel width. Finally, we proposed the sensor design strategy of considering the κ int dependences of the electrical and thermal resistances. This strategy is useful for all metal nanosheet sensors because it gives an estimation of their optimal structures.

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.

Hydrogel-based radio frequency H2S sensor for in situ periodontitis monitoring and antibacterial treatment

Periodontitis, a chronic disease, can result in irreversible tooth loss and diminished quality of life, highlighting the significance of timely periodontitis monitoring and treatment. Meanwhile, hydrogen sulfide (H2S) in saliva, produced by pathogenic bacteria of periodontitis, is an important marker for periodontitis monitoring. However, the easy volatility and chemical instability of the molecule pose challenges to oral H2S sensing. Here, we report a wearable hydrogel-based radio frequency (RF) sensor capable of in situ H2S detection and antibacterial treatment. The RF sensor comprises an agarose hydrogel containing conjugated silver nanoparticles-chlorhexidine (AG-AgNPs-CHL hydrogel) integrated with split-ring resonators. Adhered to a tooth, the hydrogel-based RF sensor enables wireless transmission of sensing signals to a mobile terminal and a concurrent release of the broad-spectrum antibacterial agent chlorhexidine without complex circuits. With the selective binding of the AgNPs to the sulfidion, the RF sensor demonstrates good sensitivity, a wide detection range (2–30 μM), and a low limit of detection (1.2 μM). Compared with standard H2S measurement, the wireless H2S sensor can distinguish periodontitis patients from healthy individuals in saliva sample tests. The hydrogel-based wearable sensor will benefit patients with periodontitis by detecting disease-related biomarkers for practical oral health management.

Achieving Room-Temperature ppb-Level H2S Detection in a Au-SnO2 Sensor with Low Voltage Enhancement Effect.

Although semiconductor metal oxide-based sensors are promising for gas sensing, low-power and room temperature operation (24 ± 1 °C) remains desirable for practical applications particularly considering the request of energy saving or net zero emission. In this study, we demonstrate a Au/SnO2-based ultrasensitive H2S gas sensor with a limit of detection (LOD) of 2 ppb, operating at very low voltages (0.05 to 0.5 V) at room temperature. The Au/SnO2-based sensor showed approximately 7 times higher response (the ratio of change in the current to initial current) of ∼270% and 4 times faster recovery (126 s) compared to the pure SnO2-based sensor when exposed to 500 ppb H2S gas concentration at 0.5 V operating voltage at relative humidity (RH) 17.5 ± 2.5%. The enhancement can be attributed to the catalytic characteristics of AuNPs, increasing the number of adsorbed oxygen species on sensing material surfaces. Additionally, AuNPs aid in forming flower-petal-like Au/SnO2 nanostructures, offering a larger surface area and more active sites for H2S sensing. Moreover, at low voltage (<1 V), the localized dipoles at the Au/SnO2 interface may further enhance the absorption of polar oxygen molecules and hence promote the reaction between H2S and oxygen species. This low-power, ultrasensitive H2S sensor outperforms high-powered alternatives, making it ideal for environmental, food safety, and healthcare applications.

An ultra-sensitive optical H2S sensor based on thermal conversion combined with UV-DOAS: Dynamic detection from ppm to ppb level

Hydrogen sulfide (H2S) as a common gas plays an important role in both industrial production and clinical pathology. Therefore, the realization of dynamic detection of trace H2S gas is of great significance. In this paper, an ultra-sensitive optical H2S sensor based on thermal conversion and ultraviolet differential optical absorption spectroscopy (UV-DOAS) is developed for dynamic measurement of H2S concentration. The H2S concentration can be derived from the measurement of the change in sulfur dioxide (SO2) concentration before and after conversion. First, the evaluation method of SO2 concentration based on UV-DOAS is presented, and the performance indicators of SO2 concentration measurement are given. Second, the conversion characteristics of H2S under different temperatures and flow rates are investigated, and H2S can be efficiently converted to SO2 in the flowing gas state by controlling the conversion conditions. Finally, the performance indicators of H2S sensor are evaluated. The sensor realizes H2S measurements with a detection limit of 14 ppb * m, while its sensitivity and reliability of measuring H2S concentration increase tenfold, making it suitable for dynamic measurements of trace H2S. In addition, the feasibility of the sensor for applications in atmospheric monitoring and human exhaled breath detection is demonstrated by practical tests.

A novel Cu-doped ZnO confined structure: Precisely preparation, and sensitization mechanism for ppb-level H2S gas detection

It is still highly desired and challengeable to design H2S sensor with high selectivity and sensitivity due to its toxicity and new application in biomarkers like monitoring halitosis. Here, we reported a novel confined structure as highly sensitive and selective H2S gas sensor. The sensing material was prepared with a HKUST-1 templated method by atomic layer deposition (ALD) ZnO decorated on HKUST-1 and calcination. The gas sensor exhibits a high gas sensitivity (Ra/Rg = 2.67 @ 2 ppm) with excellent selectivity to H2S. Furthermore, the obtained sensor shows ppb-level detection ability (Ra/Rg = 1.13 @ 0.1 ppm). Apart from releasing electrons by the oxidization of H2S on oxygen vacancies with adsorbed oxygen species O2− on ZnO surface (Langmuir-Hinshelwood mechanism), the Cu was proved to be the active sites, and would react with surficial S species. The suggestion was confirmed by operando XAS (X-ray adsorption spectrum) measurements combined with DFT calculations (Mars-van Krevelen mechanism). This work provides valuable insights for developing efficient sensing materials and understanding the sensing mechanism.