Gas Sensor Applications Research Articles

Aminated reduced graphene oxide-carbon nanotube composite gas sensors for ammonia recognition

Composites based on carbon nanomaterials exhibit many advantageous properties for gas sensing, such as high and fast response, room-temperature operation, and tailoring sensitivity by energy level engineering. However, only the first attempts to employ such chemosensors for gas-sensing applications have been made. In this work, an on-chip multisensor array of carboxylated carbon nanotubes (CNT), aminated reduced graphene oxide (rGO-Am), and CNT/rGO-Am nanocomposite was fabricated using a simple and low-cost spray deposition method. The CNT/rGO-Am sensor demonstrated a fast and high response to NH3 in dry air at low (25 ppm) and high (400 ppm) concentrations of 70 and 115 %, respectively. The response to NH3 in humid air increased and reached 160 % at 400 ppm. The chemosensor exhibited high sensitivity and selectivity toward ammonia with a low detection limit estimated to be below 0.2 ppb. Linear discriminant analysis of the sensor responses to different concentrations of NH3, dry and humid air revealed better discrimination when CNT/rGO-Am composites were used in combination with CNT and rGO-Am sensors in an array. This study demonstrates that composite sensors with junctions between carbon nanomaterials have great potential for practical applications in fast and selective gas detection at room temperature and different humidity.

The Negative Differential Resistance Effect of Substitutional Doped Monolayer GeS and Its Application in Gas Sensor

The Negative Differential Resistance Effect of Substitutional Doped Monolayer GeS and Its Application in Gas Sensor

Amorphous Bimetallic Cobalt-Based Transition-Metal Oxides for Gas Sensing Application with Regulated Selectivity

Amorphous Bimetallic Cobalt-Based Transition-Metal Oxides for Gas Sensing Application with Regulated Selectivity

Biosynthesized (SnO2/ZnO/TiO2) Composite for Gas Sensor Application: Structural and Sensing Performance Evaluation

Biosynthesized (SnO2/ZnO/TiO2) Composite for Gas Sensor Application: Structural and Sensing Performance Evaluation

A comparative study of machine learning models for identifying noxious gases through thermal fingerprint measurements and MOS sensors

Recently, there has been a notable surge of interest in developing swift and precise gas detection and categorization tools through artificial intelligence. This work specifically focuses on designing a simple sensor array configuration and empirically compares various machine-learning models for identifying multiple gases. The study employs eight metal oxide semiconductor sensors, each operating independently based on the thermal fingerprint principle. These sensors are utilized to gather data on responses to different toxic gases, and a range of traditional machine learning classifiers are trained and assessed using this dataset. The classifiers undergo investigation across various train/test dataset split ratios and different principal component analysis dimensionalities. Average accuracy metrics are employed over the entire testing dataset to evaluate model performance. The results demonstrated the challenge of selectively detecting each gas type solely through conventional analyses with the gas response data of the proposed sensor array. Nevertheless, the utilization of machine learning models has exhibited promising outcomes in augmenting gas identification and classification. The findings reveal a consistent improvement in testing accuracy for the Gradient Boosting model, which achieves an outstanding accuracy rate, with instances of reaching 100% accuracy in the training dataset when three or more principal components are considered. This study highlights the potential of the proposed straightforward sensor array and presents effective recognition algorithms applicable to creating electronic noses for gas-sensing applications.

Synthesis and characterization of Cr-doped cadmium oxide thin films for NH3 gas-sensing applications

Synthesis and characterization of Cr-doped cadmium oxide thin films for NH3 gas-sensing applications

Development of an NO2 Gas Sensor Based on Laser-Induced Graphene Operating at Room Temperature.

A novel, in situ, low-cost and facile method has been developed to fabricate flexible NO2 sensors capable of operating at ambient temperature, addressing the urgent need for monitoring this toxic gas. This technique involves the synthesis of highly porous structures, as well as the specific development of laser-induced graphene (LIG) and its heterostructures with SnO2, all through laser scribing. The morphology, phases, and compositions of the sensors were analyzed using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy. The effects of SnO2 addition on structural and sensor properties were investigated. Gas-sensing measurements were conducted at room temperature with NO2 concentrations ranging from 50 to 10 ppm. LIG and LIG/SnO2 sensors exhibited distinct trends in response to NO2, and the gas-sensing mechanism was elucidated. Overall, this study demonstrates the feasibility of utilizing LIG and LIG/SnO2 heterostructures in gas-sensing applications at ambient temperatures, underscoring their broad potential across diverse fields.

Micropatternable Ink Composed of MAX Phase ZIF-8 for Gas Sensing Applications

This work provides a detailed introduction to the preparation methods, structural characteristics, and various performance tests of the Ti3C2/ZIF-8 composite material. Initially, the composite material is obtained through the synthesis, mixing, and subsequent processing of MXene solution and ZIF-8 nanoparticles. The coating structure and properties were comprehensively characterized using SEM, TEM, and XRD. These analyses revealed the material's layered structure, high crystallinity, and surface activity. BET analysis of Ti3C2/ZIF-8 also shows excellent gas adsorption-desorption performance, having an especially high-efficiency adsorption capacity for VOCs. TGA further demonstrates the thermal stability and chemical stability of Ti3C2/ZIF-8 and its printability was tested indicating widespread application potential in coating preparation through ultrasonic spray technology. Finally, we show methods to regulate and control coating thickness and roughness for precision manufacturing. These analyses together emphasize the application value of Ti3C2/ZIF-8 in fields such as gas-storage, gas-separation, and environmental monitoring.

Improvement of gas-sensing performance of TO8C monolayers as high-efficient room-temperature NO and NO2 gas sensors induced by electric field

The gas-sensing application potential of the TO8C monolayer for the target gases (NO, NO2, CO, CO2, NH3, CH4, H2O, and H2) was systematically investigated via DFT calculations. Only NO and NO2 adsorption can tune the electronic properties of the TO8C monolayer. Since the weak adsorption strength of NO and NO2 is unfavorable for the sensor device, E-field modulation was applied. Except as the enhancement of adsorption strength into desired ranges for NO and NO2, E-field modulation of −0.14 ∼ −0.21 V/Å for NO (0.08 ∼ 0.12 V/Å and −0.26 ∼ −0.29 V/Å for NO2) makes semiconducting transfer into conducting properties, indicating the sensitivity of the monolayer towards NO and NO2 gases was also effectively improved. However, the electronic properties of TO8C monolayer adsorbed with the other gases were hardly changed by the above-mentioned E-fields. When the applied E-fields were in −0.12 ∼ −0.17 V/Å (or −0.26 ∼ −0.29 V/Å), the conducting properties for NO (or NO2) adsorption were maintained in the existence of humidity, indicating that the determinate E-field is much favorable for the TO8C-based sensor to detect NO and NO2 gases without considering whether the humidity exists. Our findings reveal that the TO8C monolayers are compelling and feasible candidates for NO and NO2 resistance-type sensors at room temperature under the E-field modulation.

Enhancing Structural Integrity, Optical Properties, and Room Temperature Formaldehyde Sensing Through Optimized Spray Deposition Rates

This study explores the impact of deposition rate on the properties of TiO2 thin films produced via spray pyrolysis, focusing on their application in gas sensors. The analysis covers structural, morphological, optical, and gas sensing characteristics of TiO2 films deposited at rates between 1 and 2.5 ml min−1. Studies show optimizing TiO2 film deposition rates at 2 ml min−1 significantly enhances formaldehyde detection, improving selectivity and achieving a rapid response of 7.52 at 20 ppm concentration. This study underscores the pivotal role of deposition rate optimization in augmenting the gas-sensing efficacy of TiO2 films, particularly for formaldehyde detection at ambient conditions. Optimal deposition rates are instrumental in enhancing sensor performance. The synergistic application of XRD and Raman spectroscopy unequivocally confirmed the presence of the TiO2 anatase phase, which is of paramount significance in gas sensing applications. FESEM furnished high-resolution insights into the surface morphology, revealing a spherical architecture. Furthermore, UV–vis spectroscopy was employed to assess the optical band gap of the films, which exhibited a decrement correlating with the rate of deposition. Notably, a deposition rate of 2 ml min−1 markedly improved the TiO2 films’ sensing performance. These insights are critical for developing cost-effective, high-performance gas sensors for cutting-edge applications.

Microheaters for Thermal Analysis and Gas Sensing Applications

Microheaters for Thermal Analysis and Gas Sensing Applications

Photovoltaic induced self-powered gas sensor based on 2D MoS2 incorporated NbSe2 nanorods heterostructure for NH3 gas sensing at room temperature

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have attracted significant attention for their optical and gas-sensing applications due to their exceptional sensitivity. Reliable selectivity and low power consumption are two major requirements for photodetector and gas sensor applications in next-generation electronic devices and the Internet of Things. Self-powered sensors (especially photovoltaic gas sensors) can solve these problems. In this study, for the first time, we report 2D TMDs (NbSe2-MoS2 hybrid) on a SiO2/Si substrate to fabricate photovoltaic self-powered gas sensors. The gas sensors are operated by the photovoltaic effect of the NbSe2-MoS2 nanostructure, which is prepared using the liquid phase exfoliation process. Initially, it was revealed that the present hybrid material exhibits photovoltaic properties under light illumination, with a circuit current of 0.25 µA and a circuit voltage of 34 mV. The NbSe2-MoS2 nanostructure characteristics were then used for NH3 gas sensing at different concentrations, and the gas sensing response was detected from low (8.8 % at 10 ppm) to high (28.8 % at 500 ppm) concentrations. The built-in electric field occurred between the NbSe2-MoS2 junction and eventually operated as a driving force for NbSe2-MoS2 gas sensing without an external bias voltage. The physisorption of gas molecules on their surface prompts a charge-transfer mechanism that improves the gas sensor response. The combined outcome of NbSe2-MoS2 heterostructures could pave way to next-generation gas sensing device fabrications.

Research on the application of WO3 gas sensor based on noble metals modification in cable fire detection

In the monitoring of cable fire, it is of great significance to be able to conduct early fire warning, which requires that sensors have high sensitivity to the cable vapors at low temperatures. In this study, WO3 thick films modified with Au, Pd, and Pt single or bimetallic nanoparticles were fabricated via magnetron sputtering. Gas sensors utilizing these materials exhibited significant response to the low-temperature vapor emitted by YJV22 and YJY23 cables. Among them, Pd/WO3-20 demonstrated a response value of 20 to the vapor of 81[Formula: see text]C YJV22 cables, marking a remarkable 6.3-fold increase compared to pure WO3, and the response time was 13 s. Similarly, Pt/WO3-10 exhibited a response value of 11.11 to the vapor of 104[Formula: see text]C YJY23 cables, representing a 6.9-fold enhancement over pure WO3 with a response time of 12 s. The heating temperature of cables remains below their critical threshold, indicating that it is in the early stages of cable fires, the findings hold significant implications for early warning systems designed to detect cable fires promptly.

Synergistic Effect of ZIF-8 and Pt-Functionalized NiO/In2O3 Hollow Nanofibers for Highly Sensitive Detection of Formaldehyde.

A rapid and accurate monitoring of hazardous formaldehyde (HCHO) gas is extremely essential for health protection. However, the high-power consumption and humidity interference still hinder the application of HCHO gas sensors. Hence, zeolitic imidazolate framework-8 (ZIF-8)-loaded Pt-NiO/In2O3 hollow nanofibers (ZPNiIn HNFs) were designed via the electrospinning technique followed by hydrothermal treatment, aiming to enable a synergistic advantage of the surface modification and the construction of a p-n heterostructure to improve the sensing performance of the HCHO gas sensor. The ZPNiIn HNF sensor has a response value of 52.8 to 100 ppm HCHO, a nearly 4-fold enhancement over a pristine In2O3 sensor, at a moderately low temperature of 180 °C, along with rapid response/recovery speed (8/17 s) and excellent humidity tolerance. These enhanced sensing properties can be attributed to the Pt catalysts boosting the catalytic activity, the p-n heterojunctions facilitating the chemical reaction, and the appropriate ZIF-8 loading providing a hydrophobic surface. Our research presents an effective sensing material design strategy for inspiring the development of cost-effective sensors for the accurate detection of indoor HCHO hazardous gas.

A sensitive NH3 chemiresistive sensor with wide detection range: Employing a MOF-derived mesoporous carbon composite with polyaniline

Designing sensing materials with effective porous structure and compositions is a crucial strategy for constructing high-performance gas-sensitive devices. Herein, a dodecahedral mesoporous carbon derived from metal-organic frameworks (CMOF), e.g. Zeolitic Imidazolate Framework-8 (ZIF-8) derived porous carbon (ZIF-8-C) was prepared, and subsequently, three-dimensional (3D) hollow dodecahedral ZIF-derived carbon-polyaniline (PANI) based (ZCPx, x representing the mass fraction of ZIF-derived carbon) hierarchical hybrid materials were constructed by introducing protonated polyaniline on the surface of MOF carbon via in-situ oxidative polymerization. The MOF-derived structure provides a substantial interface surface area for the hybrid material, enabling rapid adsorption and charge transfer, along with essential structural stability. The 3D hollow ZCP50 hybrid material prepared exhibits a wide detection range (0.1–500 ppm), repeatability, acceptable long-term stability, and an 8.3 times response enhancement versus PANI. The above performance is attributed to the significant synergistic effect between ZIF-8-C and PANI. The unique design of this 3D framework holds promising potential for the commercial application of room-temperature gas sensors.

Natural honey (Mellifera) assisted combustion synthesis of ZnO, Ag-ZnO and Fe-ZnO nanoparticles for ethanol gas sensor applications

Biogenic combustion with Mellifera (Honey) capping produced ZnO, Ag-doped ZnO, and Fe-doped ZnO nanoparticles. The phase and crystal structure of metal oxide nanoparticles (MONPs) have been recorded through XRD spectrum. It confirms that the prepared metal oxides are within the nanoscale range. The average crystallite size of Fe-doped ZnO is 8.8 nm, smaller than ZnO and Ag-doped nanoparticles. The vibrational spectra of ZnO, Ag-doped ZnO, and Fe-doped ZnO nanoparticles confirm functional group stretching vibrational modes. The exterior surface morphology of all metal oxide nanoparticles was captured by FESEM. Metal oxide nanoparticle compositional analysis shows elemental presence, atomic, and weight %. The optical properties of metal oxide nanoparticles have been examined using UV–vis spectroscopy. The band gap energy of ZnO nanoparticles reduced from 2.68 eV to 1.74 eV under Fe doing and increased to 2.9 eV under Ag doing. Metal oxide thermal stability is also being investigated to determine how it affects ZnO nanoparticles. Fe-doped ZnO nanoparticles have greater sensor properties than other metal oxides due to their tiny size, band gap, and stability. Gas sensor behaviour of three metal oxide nanoparticles was examined in various accepts. It proves Fe-doped ZnO is a promising gas sensor material.

Effect of non metallic doping in GeC gas sensors on gas response performance: the first principles study

In this paper, the stability, electronic structure and optical properties of monolayer GeC, B, N and P doped GeC systems are systematically investigated based on the first principles of density functional theory. The results show that the results show that the intrinsic GeC monolayer has a weak adsorption capacity for CH4 and C2H2, which is unfavourable for the sensing and trapping of CH4 and C2H2 gases. Based on calculated adsorption distance, adsorption energy and charge transfer, we find that P-GeC monolayer is the most sensitive to CH4 and C2H2 molecules, and the most of gas molecules act as acceptors to gain electrons from GeC monolayer. The adsorption energy of CH4 is smaller than that of C2H2 gas molecule, which implies that C2H2 is more easily desorbed from P-GeC. Moreover, the work function changes significantly when gas molecules adsorbed on B, N, P-GeC, and Recovery times indicate that B, N and P doped GeC monolayers are more selective and sensitive to C2H2 molecules compared to CH4 molecules. The research work aims to provide a theoretical basis for the application of GeC-based gas sensors, and P-doped GeC monolayers can be used as candidate materials for C2H2 gas sensing and trapping.

First principles investigation on zigzag nanoribbons of X-Nitrides (X=B,Al,Ga) for hydrogen cyanide gas sensor

This paper investigates the structural, electronic and transport calculations of varies zigzag nitride nanoribbons using DFT-framework. Based on the binding energy calculations, it is noticed that configuration bare ZXNNR with width 6 is found most structurally stable. The bare ZXNNR exhibits metallic behavior and band gap variation is also observed in pristine ZXNNR in decreasing order as increase in the width. Further, we have calculated the selectivity and recovery time of the considered structures. The highest selectivity is noticed in ZBNNR configuration. The ZGaNNR-HCN‘ configuration has lowest recovery time (56μs).The configuration ZGaNNR shows strong potential towards designing of low power and extremely fast hydrogen cyanide gas sensor applications. Present findings show that adsorption of HCN molecule can be sensed by current passing through the nanoribbons.

Amplified sensing of nitrogen dioxide with a phosphate-doped reduced graphene oxide powder

Surface chemistry plays an essential role in gas-sensing applications, enabling significant improvements in the sensing performance. This study investigates the influence of the graphene oxide (GO) synthesis route on the sensitivity to NO2 gas at room temperature (25 °C) and 100 °C in a dry and humid atmosphere. GO powders were synthesized using both the classical Hummers' method (HGO), and an improved version of the Hummers' method (IGO) using a mixture of phosphoric and sulfuric acids. The subsequent reduction (resulting in rHGO and rIGO, respectively) aimed to enhance the electrical properties and procure nanomaterials sensitive to surface adsorbates. In contrast to the HGO, both IGO and rIGO samples exhibited a transient sensor response and an outstanding recovery performance, which was attributed to the existence of phosphate groups in the latter samples. Notably, the rIGO sample achieved a 23-fold increase in response to NO2 compared to rHGO. Additionally, the limit of detection (LOD) was calculated to be 0.98 ppb at 100 °C. Computational studies considering models of GO and of GO with phosphorus-containing species demonstrate that the presence of the latter, either at the surface or below the surface, leads to a four-fold increase in the NO2 adsorption energies, hence accounting for the significant enhancement in the sensing performance observed experimentally. This underscores the importance of tailoring the structure and chemical properties of GO/rGO materials for optimal performance in gas sensing applications.

Enhanced response characteristics of NO2 gas sensor based on ultrathin SnS2 nanoplates: Experimental and DFT study

Layered-metal dichalcogenides with extraordinary characteristics of vast surface area, tunable bandgap and superior adsorption capability enable the potential for application in gas sensors. However, the synthesis of effective material for enhanced response performance remains a challenge. Herein, we exploited a fascinating sensitivity and selectivity towards NO2 gas detection using SnS2 nanoflakes prepared via the hydrothermal method. SnS2 nanoflakes with a thickness of 25 nm and an average diameter of approximately 500 nm show the potential for the detection of NO2 gas at low concentrations of ppb levels. The sensing properties of the SnS2 sensors were investigated for different concentrations of NO2 at various operating temperatures. The sensor exhibits the highest gas-sensing response of 161 at 250 οC upon exposure to 5 ppm of NO2 gas with fast response and recovery times. In addition, the sensor shows excellent selectivity with a low detection limit of ppb level. The electronic structure and gas-sensing mechanism are elucidated via finding density of states, charge density, and band structure based on DFT study which is calculated by the Vienna ab-initio simulation package (VASP). The considerable small adsorption energy reveals a physisorption of the NO2 molecules on the SnS2 surface (-0.174 eV), indicating the SnS2 nanoflakes are intriguing candidates for the speedy detection of NO2 gas.