Ammonia Sensor Research Articles

Temperature-dependent variation in ammonia sensing properties of ZnO-GO nanocomposites

Industrialization has caused significant environmental and health risks due to the emission of hazardous gases like ammonia. This study investigates the temperature-dependent gas sensing properties of a ZnO-GO nanocomposite synthesized via microwave-assisted combustion. The ammonia sensor, tested from 25 °C (room temperature) to 200 °C, showed its highest sensitivity (72 %) at 100°C for 100 ppm ammonia. It achieved a response time of 94 seconds and a recovery time of 58 seconds. These results demonstrate the potential of ZnO-GO nanocomposite sensors in reducing ammonia-related risks in industrial environments.

Optical Fiber HMS Ammonia Sensor with Cellular-like N-CQDs/MgxZn1-xO at Room Temperature.

This paper presents an optical fiber hollow malposition structure (HMS) elaborated with cellular-like N-CQDs/MgxZn1-xO for detecting ammonia (NH3) at room temperature. The gas detection was realized by combining the HMS to excite the surface evanescent field on the outer surface of the hollow core fiber (HCF) and the surface-coated cellular-like N-CQDs/MgxZn1-xO material for improving sensitivity. Experimental results demonstrate that the sensor coated with N-CQDs/Mg0.2Zn0.8O exhibits the highest sensitivity, reaching 8.9 pm/ppm, which is 11.6 times higher than that with Mg0.2Zn0.8O. Additionally, the NH3 sensor can determine a minimum concentration of 1 ppm and has response and recovery times of 6.2 and 7.1 s, respectively. Density functional theory (DFT) calculations confirm that N-CQDs reduces the bandgap of the composite material and increase the carrier concentration on its surface, thereby enhancing gas adsorption capacity. The intrinsic characteristics of the proposed sensor including small size, high sensitivity, and good stability reveal its promising prospects in detecting low concentrations of NH3.

Two-component heterojunction-based ambipolar field effect transistors for improved sensitivity of ammonia sensor

To improve the sensing response of ammonia (NH3) sensors, a two-dimensional configuration molecule 5,11-di-naphthalen-2-yl-6,12-dihydro-indolocarbazole (ICZ-NA) was designed and synthesized as the p-channel organic semiconductor material. Bilayer organic field-effect transistor (OFET) was constructed with ICZ-NA and N,N’-bis(n-octyl)-2,6-dicyanonaphthalene-1,4,5,8-bis(dicarboximide (NDI-8CN2) as p-type and n-type active semiconductor materials respectively, and the two-component devices exhibits excellent ambipolar FET performance. The thin film transistors based on single-component and two-component were further used as sensors for ammonia detection. Compared with the sensors based on NDI-8CN2, the sensitivity and selectivity of ammonia detection based on two-component sensors have been greatly improved, and the ratio of current change can still be maintained over 3.65 %, when the gas concentration lower to 10 ppb level. The higher sensing response and low limit of detection demonstrate that the two-component ambipolar configuration is a highly effective method for improving sensing response capability.

Low temperature ammonia sensor with giant sensitivity and selectivity based on W@WO2.92 internal ohmic contact core-shell nanostructures

Ammonia (NH3) detection is crucial for both harnessing hydrogen energy and safeguarding public health. However, the NH3 sensors based on semiconductors is currently constrained by their necessity to operate at elevated temperatures and their limited ability to distinguish NH3 from other gases. In this study, the high oxygen vacancy W@WO2.92 core-shell nanostructures have been synthesized by pulsed laser ablation in water. The gas sensors based on W@WO2.92 nanoparticles response to NH3 with high sensitivity (|Ra-Rg|/Ra=72.6 %@100 ppm, Ra and Rg represent the resistance of the material when exposed to air and the test gas, respectively.) at room temperature with detection limit of 730 ppb. Additionally, the response to NH3 can achieve 55 % even at 5℃, which plays a great role in timely detection of NH3 during low temperature transportation. Furthermore, the sensors reveal outstanding selectivity toward NH3 in the presence of 11 other potential interfering gases. This research presents a groundbreaking strategy, holding significant potential for the development of high-performance NH3 sensors that operate efficiently at low temperatures.

A Novel Mechanism Based on Oxygen Vacancies to Describe Isobutylene and Ammonia Sensing of p-Type Cr2O3 and Ti-Doped Cr2O3 Thin Films

Gas sensors based on metal oxide semiconductors (MOS) have been widely used for the detection and monitoring of flammable and toxic gases. In this paper, p-type Cr2O3 and Ti-doped Cr2O3 (CTO) thin films were synthesized using an aerosol-assisted chemical vapor deposition (AACVD) method. Detailed analysis of the thin films deposited, including structural information, their elemental composition, oxidation state, and morphology, was investigated using XRD, Raman analysis, SEM, and XPS. All the gas sensors based on pristine Cr2O3 and CTO exhibited a reversible response and good sensitivity to isobutylene (C4H8) and ammonia (NH3) gases. Doping Ti into the Cr2O3 lattice improves the response of the CTO-based sensors to C4H8 and NH3. We describe a novel mechanism for the gas sensitivity of p-type metal oxides based on variations in the oxygen vacancy concentration.

A highly sensitive and selective ZnO-based ammonia sensor: Fe- doping effect

Abstract This study investigates the gas sensing capabilities of ZnO and Fe-doped ZnO films prepared via a cost-effective spin coating method. The films were characterized optically, structurally, and morphologically. X-ray diffraction revealed good crystal quality with a polycrystalline nature, and wurzite structure, though crystal quality and crystallite size decreased with Fe doping. Optical measurements indicated an increased optical band gap from 3.205 ± 0.002 to 3.220 ± 0.002 eV after Fe doping. Scanning electron microscope images confirmed spherical grainy structures with reduced grain sizes after Fe doping. Gas sensing measurements at room temperature (RT) at an exposure of vapors of various toxic chemicals (acetone, ethanol, propanol, methanol, and ammonia), demonstrated a highly selective nature of ZnO and Fe-ZnO towards the ammonia. The Fe-doping into ZnO improved the ammonia sensing capability of ZnO film. The Fe-ZnO film exhibited a gas response of 388.8 ± 5.5 at 400 ppm ammonia exposure, which was nearly 10 times larger than that of ZnO film with a response/recovery time of 22/51 s, good stability, and good repeatability. The Fe-ZnO film’s higher response is attributed to its smaller grain sizes and surplus of charge carriers after Fe doping which promote the adsorption of extra oxygen ions onto the film’s surface and the subsequent interaction between the adsorbed oxygen ions ammonia molecules. It could detect up to the lower limit of 1 ppm ammonia with a response of 24.2 ± 0.9, which is better than the previous reports. These results reveal the Fe-ZnO film as a viable material for developing a cost-effective and efficient ammonia sensor at room temperature.

MXene anchored fabric for room-temperature operated ammonia sensing

Low-cost and fast-response fabric sensors are highly desirable for shop floor worker daily monitoring and early trace ammonia leak detection. However, the difficulty is how to establish a high bonding capacity between the active material and the fabric to meet the needs of sensing performance on practical applications. Herein, MXene anchored fabric sensors have been fabricated by spray casting technology and the impacts of the preparation process on sensor performance have been investigated. When the casting concentration of MXene is 10 mg/mL and the fabric is spandex, the ammonia sensor exhibits the best sensing performance with a response time of 0.62 s for 100 ppm ammonia and a low limit of detection of 0.4 ppm. Notably, when the sensor used for detection ammonia in wafer cleaner volatiles, the responsivity was up to 96.61 %. This research offers an efficient route for developing MXene anchored fabric for room-temperature operated ammonia sensing.

Optimizing Ammonia Detection with a Polyaniline-Magnesia Nano Composite.

Polyaniline-magnesia (PANI/MgO) composites with a fibrous nanostructure were synthesized via in situ oxidative polymerization, enabling uniform MgO integration into the polyaniline matrix. These composites were characterized using FTIR spectroscopy to analyze intermolecular bonding, XRD to assess crystallographic structure and phase purity, and SEM to examine surface morphology and topological features. The resulting PANI/MgO nanofibers were utilized to develop ammonia (NH3) gas-sensing probes with evaluations conducted at room temperature. The study addresses the critical challenge of achieving high sensitivity and selectivity in ammonia detection at low concentrations, which is a problem that persists in many existing sensor technologies. The nanofibers demonstrated high selectivity and optimal sensitivity for ammonia detection, which was attributed to the synergistic effects between the polyaniline and MgO that enhance gas adsorption. Furthermore, the study revealed that the MgO content critically influences both the morphology and the sensing performance, with higher MgO concentrations improving sensor response. This work underscores the potential of PANI/MgO composites as efficient and selective ammonia sensors, highlighting the importance of MgO content in optimizing material properties for gas-sensing applications.

Fe(OH)3/Ti3C2Tx nanocomposites for enhanced ammonia gas sensor at room temperature

Two-dimensional material (2D material) MXene has great application potential in gas sensors because of its excellent controllable performance and vast specific surface area. In this study, we used a straightforward in-situ electrostatic self-assembly technique to create Fe(OH)3/Ti3C2Tx nanocomposites, which were then used to fabricate gas sensors for ammonia detection at room temperature (25 ℃). Several characterization methods were performed aimed at determining the surface appearance and construction of the nanocomposites, and the sensing characteristics and mechanism were also systematically examined. The findings demonstrate the effective incorporation of amorphous Fe(OH)3 nanoparticles on the surface of Ti3C2Tx. Additionally the nanocomposites of Fe(OH)3/Ti3C2Tx have considerably higher specific surface area than pure Ti3C2Tx, hence offering more active NH3 adsorption sites. The response of the sensor to 100 ppm NH3 was 48.6% at room temperature, which was 9.3 times more higher than that of pure Ti3C2Tx. The sensors also have the advantages of long-term stability (33 days), low NH3 detection limit (500 ppb), and rapid recovery time (85 s) and response times (78 s). It is anticipated that this work will be helpful for developing the new generation of wearable ammonia sensors at room temperature.

High Sensitivity Bi2O3/Ti3C2Tx Ammonia Sensor Based on Improved Synthetic MXene Method at Room Temperature.

The MXene Ti3C2Tx was synthesized using hydrofluoric acid and an improved multilayer method in this study. Subsequently, a Bi2O3/Ti3C2Tx composite material was produced through hydrothermal synthesis. This composite boasts a unique layered structure, offering a large surface area that provides numerous contact and reaction sites, facilitating the adsorption of ammonia on its surface. The prepared Bi2O3/Ti3C2Tx-based sensor exhibits excellent sensing performance for ammonia gas, including high responsiveness, good repeatability, and rapid response-recovery time. The sensor's response to 100 ppm ammonia gas is 61%, which is 11.3 times and 1.6 times the response values of the Ti3C2Tx gas sensor and Bi2O3 gas sensor, with response/recovery times of 61 s/164 s at room temperature, respectively. Additionally, the gas sensitivity mechanism of the Bi2O3/Ti3C2Tx-based sensor was analyzed, and the gas sensing response mechanism was proposed. This study shows that the sensor can effectively enhance the accuracy and precision of ammonia detection at room temperature and has a wide range of application scenarios.

Water Quality Monitoring and Control System for Tilapia Cultivation Based on Internet of Things

This research analyzes the quality of water for tilapia habitat which is a type of brackish water fish that is currently widely cultivated by pond farmers. This fish is the choice because of its flexibility regarding habitat. However, despite having flexibility in terms of habitat, each harvest of tilapia that lives in a different habitat will produce tilapia with different quantity and quality. Currently, many tilapia farmers still carry out the cultivation process using traditional methods using ponds. Kuala Kerto Village, Lapang District, North Aceh is one of the locations where many tilapia fish farmers use ponds as a habitat for this fish. Not infrequently, changes in natural conditions such as rain and floods have an impact on tilapia fish ponds in this village. Thus, crop yields are very varied, often even resulting in losses. One of the reasons for this is that there is still minimal use of technology in tilapia cultivation in this village. The design of a water quality monitoring and control system for IoT-based tilapia cultivation in this research was carried out to help the problems of tilapia pond farmers. Through this research, a tool was produced in the form of a prototype IoT device that can be used to monitor and control water quality in tilapia fish ponds. This device utilizes several sensors such as turbidity sensors, ammonia sensors, salinity sensors, pH sensors, and several other sensors as data takers which will later be transmitted and displayed via a web application. Research and development of this device uses the RD method, namely research and development.

γ- WO3 decorated MXene: An advanced nanomaterial for room temperature operable enhanced ammonia sensor

The proliferation of Internet of Things (IoT) applications necessitates the deployment of high-performance ammonia (NH3) sensors. In recent studies, Ti3C2Tx, a novel two-dimensional (2D) material, has been extensively investigated for its potential as a room temperature NH3 sensor. However, pristine MXene-based sensors have exhibited deficiencies in long-term stability and reproducibility. In response, an MXene/γ-WO3 composite has been synthesized using an ultra-sonication method to address these challenges. The resulting composite sensor has demonstrated remarkable performance, attributable to, increased active sites from defects induced by WO3, and the presence of a p-n heterojunction. Notably, electron transfer from WO3 to Ti3C2Tx has been identified as a critical contributing factor to the enhanced characteristics of these nanohybrids, as evidenced by observed alterations in binding energies for the Ti 2p and W 4f core levels. These findings have expanded our understanding of the electrical interactions in Ti3C2/WO3 and their potential applications in diverse domains. The pristine MXene sensor exhibited a response of 59.39% at 300 ppm at room temperature, while the composite MXene/γ-WO3 displayed a response of 92.3%. Additionally, the response recovery time was recorded at 22seconds and 9seconds, respectively. The chemiresistive ammonia sensor's performance was evaluated across a range of concentrations (25–300 ppm) and relative humidity levels (11–94% RH). The composite sensor has demonstrated reproducibility and long-term stability, coupled with high sensitivity to NH3. This manuscript aims to highlight the enhanced ammonia sensing properties and selectivity of MXene/γ-WO3 composite materials.

Co3O4/CQDs composite for selective ammonia detection in exhaled human breath analysis

Co3O4 was synthesized using electrospinning method and different amounts of carbon quantum dots (CQDs) were subsequently doped into the Co3O4 matrix via grinding, resulting in Co3O4/CQDs composite materials with various ratios. Gas sensing tests revealed that the resulting composite Co3O4/CQDs sensors exhibited excellent performance at a low temperature of 50°C, with outstanding selectivity towards ammonia gas and rapid response and recovery characteristics. Specifically, response and recovery time for 50 ppm ammonia gas were 14 s and 164 s, respectively. The outcomes of the exhalation simulation test utilizing sensors composed of this material demonstrate that the sensor's response to simulated chronic kidney disease breath closely approximates that of pure biological samples (1.08), exceeding the average response value of healthy exhaled breath samples (1.0). This demonstrates the sensor's capability to differentiate between healthy individuals and chronic kidney disease patients despite significant water vapor and carbon dioxide interference. This study provides valuable insights for the development of more efficient ammonia sensors and their role in the early detection of chronic kidney disease.

Preparation and Ammonia Sensing of Copper Iodide Nanomaterials Combined with Copper Iodide‐Isopropanolamine Complexes

AbstractWith the increasing awareness of the hazards associated with ammonia (NH3) contamination and the potential application of NH3 detection in physical health monitoring, the exploration of high‐performance NH3 sensors has attracted significant attention in recent years. In this paper, we prepared copper iodide (CuI) nanomaterials combined with CuI‐isopropanolamine (C3H9NO) complexes by dissolving CuI in C3H9NO and subsequent annealing. The resulting product demonstrated exceptional sensing performance to 0.15 (mole fraction) NH3, exhibiting a maximum response of 7.5×105 with a response time of 5 s. The achieved detection limit was 10 ppm. Our findings provide a valuable reference for further research on NH3 sensors utilizing complexes formed by copper compounds and organic amines.

Enhanced ammonia detection using rGO-wrapped Zn3V2O8 nanostructures

This study presents the synthesis and characterization of reduced graphene oxide (rGO)-wrapped Zn3V2O8 nanostructures, highlighting their enhanced ammonia sensing capabilities. Utilizing advanced techniques such as XRD, TEM, HRTEM, XPS, and Raman spectroscopy, the microstructural, compositional, and crystalline properties of the rGO/ Zn3V2O8 composites were thoroughly analyzed. The integration of rGO significantly improves the electrical conductivity, surface area, and chemical reactivity of the Zn3V2O8, resulting in superior sensing performance. Notably, the rGO/Zn3V2O8:2 composite exhibits rapid response and recovery times when detecting ammonia at room temperature, demonstrating its potential as an effective material for advanced gas sensing applications. These findings contribute to the ongoing development of high-performance ammonia sensors, offering a promising approach for real-time environmental monitoring and industrial applications.

Highly sensitive room-temperature ammonia sensor based on PbS quantum dots modified SnS2 nanosheets and theoretical investigation on its sensing mechanism by DFT calculation

Real-time accurate detection of hazardous gases is an urgent issue for industrial development and safeguarding public health. However, large-scale application of gas sensors in the network requires low-power consumption of sensing device for successful integration in smart platform. Although traditional ammonia (NH3) sensors based on semiconductor materials possess various advantages, it still remains the challenge in high operating temperature. Herein, PbS quantum dots (QDs) with higher adsorption energy were used to sensitize SnS2 nanosheets with electron transport capacity to achieve excellent NH3 sensing performance. PbS QDs with an approximately diameter of 10 nm were dispersed on SnS2 nanosheets with an average thickness of 14 nm. Impressively, the optimal sensor employing PbS QDs/SnS2 nanocomposites exhibited high sensor response of 8.5 to 100 ppm NH3, good response/recovery times of 9 s/720 s, as well as excellent selectivity, repeatability, and long-term stability at room temperature of 25 °C. The adsorption behavior and electronic structure of PbS QDs/SnS2 nanocomposites before and after NH3 adsorption were investigated based on density functional theory calculation. Moreover, the sensing mechanism of PbS QDs/SnS2 nanocomposites was also discussed. The designed PbS QDs/SnS2 nanocomposites hold considerable promise as a candidate in realizing superior NH3 sensing performance at room temperature.

Enhanced sensing properties of optical ammonia sensor based on electrospun fibers containing Eosin-Y and silver nanoparticles

This study presents a highly sensitive fluorescence intensity-based gas sensor specifically designed to detect ammonia. Eosin-Y fluorescent dye and silver nanoparticles are incorporated into` cellulose acetate to fabricate fibers membrane using the electrospinning technique, which serves as the foundation for the optical ammonia sensors. Afterward, this sensor is illuminated by a 405 nm LED for monitoring purposes, resulting in changes to both intensity and wavelength. The sensitivity of the optical ammonia sensor is evaluated by comparing the fluorescence intensity recorded for pure nitrogen with that for 1000 ppm ammonia, expressed as the ratio I0/I1000 ppm. The sensor's ability to detect ammonia is evaluated based on the differences in fluorescence intensities between nitrogen and ammonia environments. The proposed optical ammonia gas sensor utilizes Eosin-Y molecules as indicator compounds. Notably, the sensor, constructed from an electrospun fiber membrane, demonstrates an exceptional response of 50.9 at 1000 ppm in an ammonia gas environment at room temperature, representing the highest response achieved to date in an ammonia gas sensor utilizing Eosin-Y molecules. Experimental findings highlight the enhanced sensitivity of the proposed Eosin-Y-containing electrospun fibers compared to traditional Eosin-Y-based dyes for optical ammonia sensing. The development of an optical ammonia sensor utilizing electrospun fibers embedded with fluorescent dye presents a promising opportunity, offering practical applicability due to its cost-effectiveness and straightforward manufacturing process. Finally, the innovative optical ammonia sensor approach can be applied across various fields, including environmental, industrial, and medical applications.

Nanostructured NiO-polyaniline fibers composite smart material as a room temperature ammonia sensor

Nanostructured NiO-polyaniline fibers composite smart material as a room temperature ammonia sensor

Fabrication of Graphene-based Ammonia Sensors: A Review

Abstract: Graphene gas sensors have gained much scientific interest due to their high sensitivity, selectivity, and fast detection of various gases. This article summarizes the research progress of graphene gas sensors for detecting ammonia gas at room temperature. Firstly, the performance and development trends of the graphene/semiconductor Schottky diode sensor are discussed. Secondly, manufacturing methods and the latest developments in graphene field-effect transistor sensors are reviewed. Finally, the basic challenges and latest efforts of functional ammonia gas sensors are studied. The discussion delves into each sensor type's detection principles and performance indicators, including selectivity, stability, measurement range, response time, recovery time, and relative humidity. A comparative analysis is conducted to highlight the progress achieved in research, elucidating the advantages, disadvantages, and potential solutions associated with various sensors. As a result, the paper concludes by exploring the future development prospects of graphene-based ammonia sensors.

Naphthalene Diimide‐Based Hydrogen‐Bonded Organic Framework for High Electrical Conductivity and Ammonia Sensor Applications

Naphthalene Diimide‐Based Hydrogen‐Bonded Organic Framework for High Electrical Conductivity and Ammonia Sensor Applications