Gas Sensor Applications Research Articles

Optical and ammonia sensing properties of Mn doped ZnO nanostructured films for gas sensors application

Optical and ammonia sensing properties of Mn doped ZnO nanostructured films for gas sensors application

Synthesis and Characterization of Mg-doped ZnO Nanoparticles for Gas-sensing Applications

Synthesis and Characterization of Mg-doped ZnO Nanoparticles for Gas-sensing Applications

Synthesis and Characterization of Nanostructured Cerium-Doped Zinc Oxide Thin Films for Selective Nitrogen Dioxide Gas Sensing Applications

Zinc oxide thin films doped with cerium were synthesized through facile spray pyrolysis technique and subsequently characterized via an array of analytical methods, including X-ray diffraction, ultraviolet-visible diffused reflectance absorption spectroscopy, photoluminescence, scanning electron microscopy and energy-dispersive X-ray spectroscopy techniques. The operative mechanism of the semiconductor metal oxide gas sensors is predicated on the modulation of electrical conductivity in response to varying gaseous atmospheres, under the influence of disparate thermal conditions. The nitrogen dioxide gas-sensing performance of the films demonstrated a noteworthy gas response of 18% at an elevated temperature of 400°C for a concentration of 100 ppm, accompanied by rapid response and recovery times of 23 and 60 s, respectively.

Exploring the ammonia gas sensing properties of Gd doped CeO2 thin films deposited by spray pyrolysis method

The present study investigates the synthesis and characterization of Gd-doped CeO2 thin films using a simple nebulizer spray pyrolysis method for ammonia sensing application. The films were prepared with varying Gd concentrations from 1 to 5 wt%. The structural, morphological, and optical properties of the samples were analyzed to examine the effect of Gd doping on physical parameters, and the results show that the 4 wt% Gd doped sample exhibits the highest crystallite size, uniform particle size distribution, and a smaller optical band gap. Additionally, the presence of defects and oxygen vacancies in the host lattice is enhanced in this sample. The gas sensing properties of the 4 wt% Gd doped CeO2 exhibits a gas responsivity of 731 %, rise time of 10.4 s, and fall time of 9.2 s indicating that the fabricated thin film sensor was found to be ideal for room temperature gas sensing application. Overall, the study demonstrates that the 4 wt% Gd doped CeO2 thin film is a promising candidate for commercial gas sensor applications.

Fabrication of crystalline silicon nanowires coated with graphene from graphene oxide on amorphous silicon substrate using excimer laser

In this work, we report a single-step graphene-coated crystalline silicon nanowires (SiNWs) manufacturing technique. We report a one-step fabrication technique of SiNWscoated reduced graphene oxide using a krypton fluoride (KrF) excimer laser. The SiNWs have been manufactured by redistributing the silicon mass within the sample without etching any of the deposited amorphous silicon (a-Si) and then adding a synthesized graphene oxide suspension using the modified Hummers' method. The process is optimized to ensure that the graphene is completely reduced and that the crystalline nanowires are formed. In order to allow full control of the dimension of the generated nanowires, the properties of the excimer laser have been investigated. Additionally, graphene-coated Si nanowires have also been synthesized to be used for gas-sensing applications in the future. In this work, we are eviting the repetition of the previously published work by the same research group for the sake of brevity. But the reader can refer to the previously published work on the study of the effect of different parameters on the SiNWs growth like the study of the effect of changing the normalized frequency on the size of the grown SiNWs in terms of length and diameter as well as other parameters mentioned in the previously published work in the references.

Synthesis and Characterization of Co2O3 Thin Films by Pulsed Laser Deposition Method and Investigation Zscan and Gas Sensing Applications

Synthesis and Characterization of Co2O3 Thin Films by Pulsed Laser Deposition Method and Investigation Zscan and Gas Sensing Applications

Enhanced Ethanol Gas Sensor Performance through Adsorption Energy Analysis of Gd-Doped LaFeO3 with rGO Coating: A Density Functional Theory Study

LaFeO3 (LFO) is commonly used as a material for gas sensor applications. However, the LFO material in ethanol gas sensor applications can still improve sensitivity and selectivity parameters. Gadolinium (Gd) doping is widely used in gas sensor applications to increase the sensitivity of gas sensors. In addition, reduced graphene oxide (rGO) materials are commonly used in gas sensor applications to increase gas sensors' selectivity, sensitivity, and working temperature. This study analyzed the effect of Gd doping (LGFO) and the addition of an rGO single layer on LFO material (LGFO@rGO) on sensitivity and selectivity based on the adsorption energy of the system with ethanol gas molecules. Density Functional Theory studies were conducted to yield insight into the LGFO or LGFO@rGO – ethanol gas interactions and the sensitivity and selectivity improvement by changing adsorption energy. Based on the analysis, the presence of Gd doping and single-layer rGO could increase the adsorption energy. The addition of the rGO layer showed an escalation of the adsorption energy of about 9.45%, 2.49 eV in the LGFO to -2.75 eV LGFO@rGO. This improved adsorption capacity translates to a higher sensitivity for detecting lower concentrations of ethanol gas. This result shows the potential of LGFO and LGFO@rGO as ethanol gas sensor materials.

ZnO/TiO2 hetero-structured nanosheets for effectively detecting formaldehyde at room temperature

In this study, ZnO/TiO2 nanosheets were synthesized using a hydrothermal method followed by annealing. The resulting hierarchical ZnO–TiO2 heterostructures exhibited improved gas-sensing performance compared with pure ZnO. We demonstrated that tuning the ratio of Zn to Ti components in the heterostructure allowed us to adjust the sensor stability, with the best- performing sample having a Zn:Ti ratio of 2:1. A notable reduction was observed in both the sensor response and recovery times, down to 22 and 17 s, respectively, by utilizing nanosheet- structured ZnO/TiO2 heterojunctions. To gain insight into the interaction between the sensing materials and formaldehyde (HCHO) molecules, we performed first-principles calculations to examine the density of states, charge transfer, and energy of adsorption. Our approach to constructing heterogeneous structures contributes to overcoming the low desorption efficiency and slow response-recovery time of pure ZnO for gas-sensing applications.

Optical properties of NiO films: Effect of nitrogen-doping, substrate temperature and band gap estimation using machine learning

In this study, nickel oxide (NiO) thin films were synthesized on glass substrates using RF magnetron sputtering with varying nitrogen (N) doping ratio and substrate temperatures to explore modifications in their structural, morphological, and optical properties. The films were prepared using a high-purity NiO target under controlled sputtering conditions. Structural analysis by X-ray diffraction revealed an improvement in crystallinity in the (200) direction with increasing N ratio. In contrast, higher N ratio led to the suppression of (111) and (220) peaks, indicating a significant influence of N on the crystal structure and orientation. The films’ thickness and morphology, examined using scanning electron microscopy and energy-dispersive X-ray spectroscopy, showed uniform and homogeneous growth with smooth surface topologies. Optical properties, assessed by UV–Vis-NIR spectrophotometry, demonstrated a decrease in transmittance and a redshift in the absorption edge with increased N doping, corresponding to a narrowing of the energy bandgap from 3.7 eV to 3.45 eV. This bandgap reduction is attributed to N incorporation substituting oxygen sites, introducing defect states within the band structure. Additionally, the impact of substrate temperature on film growth enhanced crystallinity and orientation along the (111) plane at higher temperatures, with a simultaneous reduction in film thickness due to increased adatom mobility and potential thermal decomposition. The evaluation of Kernel Ridge Regression (KRR) and Ridge Regression (RR) models revealed their effectiveness in predicting band gap values for thin films at varying substrate temperatures and thicknesses. While RR excelled in predicting a band gap of 3.6 eV for a film with a substrate temperature of 24 °C and a thickness of 112.7 nm, KRR outperformed in predicting a band gap of 3.65 eV for a film with a substrate temperature of 24 °C and a thickness of 107 nm. These findings elucidate the dual influence of N doping and substrate temperature on enhancing the functional properties of NiO thin films, promising for applications in optoelectronic devices and gas sensors.

Gas‐sensing properties of polyaniline‐based nanocomposites for d‐limonene detection

AbstractThis paper introduces a novel wearable flexible gas sensor designed specifically for the detection of d‐limonene. The sensor utilizes materials recognized for their high efficiency‐to‐cost ratio, notably polyaniline (PANI) combined with carboxylated multiwalled carbon nanotubes (MWCNT) and graphene oxide (GO) as sensing layers. The study conducts a comprehensive analysis of the nanocomposite layers, examining their functional groups, morphology, topography, thickness, crystallinity, thermal behavior, surface area, as well as the size and volume of their pores. This examination showed distinctions among the nanocomposite layers. PANI/GO exhibited larger pore size and thickness, while PANI/MWCNT_COOH demonstrated a higher surface area. The analysis of thermal stability demonstrated that the film employing the DBSA dopant exhibited the lowest stability. Morphological characterizations showed a globular structure for PANI, tubular characteristics for PANI/MWCNT_COOH, and a flat nature for PANI/GO. When detecting d‐limonene, nanocomposite films doped with HCl demonstrated notably superior response levels. The gas sensors exhibited high sensitivity (>2.24 mV/ppm), a narrow range for the limit of detection (0.12–0.52 ppm), and excellent reversibility, stability, and selectivity. These findings suggest the possibility of broadening the application of gas sensors to monitor additional volatile compounds, with a particular emphasis on the online monitoring of agricultural products.

Industrial zone-based harmful gas sensor using pure WS2 via doping transition metals (Co, Ni) - a DFT approach

Tungsten disulphide (WS2) has received a lot of interest for its usage in a variety of fields due to its acceptable bandgap and various traits/characteristics. Presently, density functional theory (DFT) has been deployed to thoroughly study the adsorption characteristics of gases (NO, NO2, NH3, BCl3, & SO2) on Y-WS2 (Y = Co, Ni) by determining the adsorption distance, adsorption energy, electron difference density, charge transfer, electron localisation function, recovery time, & work function, also by comparing the band structure, the density of states and the projected density of states. Our results show that Y-WS2 has better conductivity and enormous charge transfer than pure WS2. Additionally, the Y-WS2 exhibits stronger adsorption of more than −0.5 eV for the harmful gases NO2, BCl3, and SO2. Subsequently, for Y-WS2, there is electron localisation overlap only for the BCl3 gas adsorbed system, which highlights the chemisorption character of the gases. Due to the high adsorption energy, Y-WS2 takes a longer time to recover NO2, BCl3, and SO2 gases at ambient temperature. However, by raising the temperature to 673 K, we can quickly recover these molecules from Y-WS2 in a few microseconds. We came to the conclusion that Y-WS2 is the right approach for NO2, BCl3, and SO2 gas-sensing applications.

Recent Progress in the Applications of Langmuir-Blodgett Film Technology.

Langmuir-Blodgett (LB) film technology is an advanced technique for the preparation of ordered molecular ultra-thin films at the molecular level, which transfers a single layer of film from the air/water interface to a solid substrate for the controlled assembly of molecules. LB technology has continually evolved over the past century, revealing its potential applications across diverse fields. In this study, the latest research progress of LB film technology is reviewed, with emphasis on its latest applications in gas sensors, electrochemical devices, and bionic films. Additionally, this review evaluates the strengths and weaknesses of LB technology in the application processes and discusses the promising prospects for future application of LB technology.

Wavelength Tuning in Resonant Cavity Interband Cascade Light Emitting Diodes (RCICLEDs) via Post Growth Cavity Length Adjustment.

We demonstrate substrate-emitting resonant cavity interband cascade light emitting diodes (RCICLEDs) based on a single distributed Bragg reflector (DBR). These devices operate in continuous wave mode at room temperature. Compared to standard ICLEDs without a cavity, we achieved an 89% reduction in the emission spectrum width, as indicated by the Full Width Half Maximum (FWHM) of 70 nm. Furthermore, we observed far-field narrowing and improved thermal stability. A single DBR configuration allows the cavity length to be adjusted by adding refractive index-matched material to the top of the epitaxial structure after epitaxial growth. This modification effectively shifts the cavity response towards longer wavelengths. We fabricated emitters comprising two cavities of different lengths, resulting in the emission of two distinct spectral lines that can be independently controlled. This dual-color capability enables one of the emission lines to serve as a built-in reference channel, making these LEDs highly suitable for cost-effective gas-sensing applications.

Utilization of jarosite and manganite mineral as raw material to fabricate metal-oxide composite film for gas sensor application

This study explores the utilization of Indonesia’s abundant geological resources, specifically jarosite and manganite minerals, to develop composite films for ethanol gas sensing applications. With jarosite’s Fe2O3 composition and manganite’s diverse applications in manganese oxide minerals, these minerals serve as promising raw materials. Building on prior research that employed Fe2O3 and manganese oxide composites, our focus lies in creating a cost-effective composite film comprising iron, manganese, and zinc oxides to enhance ethanol gas sensing capabilities. The fabrication process involves mineral extraction through a precipitation method, followed by composite synthesis and film formation using a screen-printing technique. Analysis of the resulting composite film’s morphological and crystal structure through SEM and XRD machines provides porosity and crystallinity characteristics. Examining electrical characteristics reveals the gas sensor behavior, emphasizing sensitivity and response in an ethanol environment. This study aims to contribute to gas sensor technology advancements, leveraging Indonesia’s geological wealth, promoting cost efficiency, and addressing critical aspects of sensitivity in gas sensor applications.

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