Ethanol Sensor Research Articles

Highly sensitive ethanol sensor based on zinc oxide-based nanomaterials with low power consumption

Highly sensitive ethanol sensor based on zinc oxide-based nanomaterials with low power consumption

WO3 nanorods structures for high-performance gas sensing application

Gas sensing ability of one dimensional (1D) semiconducting WO3 Nanorods with remarkable aspect ratio is characterized. The WO3 sensor exhibited high response towards 10–100 ppm ethanol at 250 °C; 95% response for 100 ppm and 61% response at 10 ppm ethanol. The sensor revealed high selectivity towards ethanol among various gases. The dynamic response for different concentrations of ethanol was recorded and analysed. The sensor’s repeatability was noted by transient response study for 100 ppm ethanol. The sensor stability and hypothesized sensing mechanism were discussed. According to the results, WO3 nanorods with high aspect ratio would be used in advanced ethanol sensor application.

Rational design of Bi-doped rGO/Co3O4 nanohybrids for ethanol sensing

Gas sensors based on metal oxide semiconductors (MOSCs) and reduced graphene oxide (rGO) for sensing of organic volatile compounds often suffer from high operation temperature, low responses, poor selectivity, or narrow detection range. Herein, we design and fabricate Bi-doped rGO/Co3O4 (BGCO) nanohybrids with a flower morphology, which have been applied as a sensing layer for an ethanol sensor. This BGCO sensor exhibits a maximum p-type response of 178.1 towards 500 ppm ethanol at an optimum working temperature of 120 °C. The sensor’s detection range for the ethanol concentration is from 500 ppb to 500 ppm, and the sensor has an excellent selectivity to ethanol compared to other types of organic volatile gases and oxidizing gas such as NO2. The enhanced ethanol sensing mechanism is attributed to the increased conductivity of Bi doped rGO/Co3O4 material. Additionally, incorporation of Bi dopant can promote the redox reaction, and the rGO/Co3O4 act as the catalyst.

The dual role of the surface oxophilicity in the electro-oxidation of ethanol on nanostructured Pd/C in alkaline media

• Pd/C electrocatalysts are used for amperometric sensors and also for Fuel Cells. • Size-induced effects on Pd/C resulted in distinct tendency to interact with oxygen. • Electrocatalytic activity towards ethanol oxidation depends on the surface oxophilicity. • PdO acts both as a promoter and/or inhibitor towards ethanol oxidation. • The catalytic activity can be enhanced by 57% only by varying surface oxophilicity. The ability of a surface to interact with oxygen (oxophilicity) plays a very important role in several catalytic, electroanalytic and electrocatalytic reactions. To date, however, the role of the oxophilicity in the electrochemical oxidation of ethanol was never shown for pure nanostructured Pd electrocatalysts supported on carbon, a promising material to be used as a non-enzymatic amperometric sensors for ethanol and also as an electrocatalyst for the Direct Ethanol Fuel Cells. In this work, Pd nanoparticles were prepared by chemical reduction at room temperature in the presence of varying amounts of sodium citrate in order to produce particles with distinct sizes. Then, we used cyclic voltammetry in 0.1 mol L -1 KOH to obtain an oxophilicity trend among various nanostructured Pd/C samples. The oxidation of ethanol in alkaline media demonstrated that the surface oxophilicity has a dual role in the kinetics of the reaction: a promoter at low and medium oxygen coverages, and a spectator (inhibitor) species at high surface coverages. Thus, by a proper control of the surface oxophilicity the current density at a constant potential can be enhanced by 57%, highlighting the importance of that parameter in the electro-oxidation on ethanol on Pd-based materials. Our results have a great impact for the design of more active non-enzymatic ethanol sensors and also for the development of more active electrocatalysts for Direct Ethanol Fuel Cells.

Zinc oxide nanonets with hierarchical crystalline nodes: High-performance ethanol sensors enhanced by grain boundaries

Researchers commonly enhance the sensitivity of gas sensing nanomaterials by increasing the effective active area. It would be more straightforward to instead optimize the grain boundaries. In this work, Zn4CO3(OH)6·H2O was synthesized as a precursor to ZnO via a facile hydrothermal process and annealing, respectively. ZnO nanonets of hierarchical crystalline nodes with abundant grain boundaries was prepared. The nanonets exhibited an ultra-sensitive response value of 398, and a fast response time (4 s of exposure to 100 ppm ethanol), compared with traditional nanosheets. The sensing enhancement as per the grain boundary was modeled and experiments confirmed the model. Microstructural and microscopic analyses indicated that the sensitivity of the nanonets mainly is attributable to the abundant grain boundaries with lots of hierarchical crystalline nodes. The high-sensitive response and fast response time toward ethanol by the ZnO nanonets is considered to derive from the enhancement effect of grain boundaries in hierarchical crystalline nodes, which creates the additional depletion layers from abundant oxygen vacancies led to a substantial change in the surface potential, referring to the difference between in-air versus in-ethanol. The proposed high-performance sensor is inexpensive to fabricate, straightforward to synthesize, and advantageous for practical use.

Ce-doped LaCoO3 film as a promising gas sensor for ethanol

With increasing exposure to ethanol in various scenarios, including hand sanitizers that combat bacteria and viruses, energy-efficient miniaturized sensors capable of detecting excessive concentrations of ethanol are required in the fields of disinfection and chemical storage. Modified perovskite-type oxides with ABO3 structures are particularly attractive because they can be appropriately modified and have been used in heterogeneous catalysis and gas sensors. In this study, we designed and manufactured a novel thin-film-type LaCeCoO3 gas sensor using lithography technology and precursor-solution doping. The samples exhibited morphologies that contain randomly oriented nanostructures and short rods; the particle size was observed to decrease with Ce-addition. Room-temperature gas-sensing characterization studies revealed high reproducibility for the detection of ethanol. La0.96Ce0.04CoO3 exhibited superior stability and sensitivity, with a high impedance, |Z|, of ∼120 kΩ and a Δ|Z| of up to 77%, with response and recovery times of 16 and 8 s, respectively. This study provides a rational method for the development of LaCeCoO3 as a semiconducting material for ethanol gas-sensing applications.

Adsorption, Gas-Sensing, and Optical Properties of Molecules on a Diazine Monolayer: A First-Principles Study.

Using first-principles calculations, the structural, electronic, and optical properties of CO2, CO, N2O, CH4, H2, N2, O2, NH3, acetone, and ethanol molecules adsorbed on a diazine monolayer were studied to develop the application potential of the diazine monolayer as a room-temperature gas sensor for detecting acetone, ethanol, and NH3. We found that these molecules are all physically adsorbed on the diazine monolayer with weak adsorption strength and charge transfer between the molecules and the monolayer, but the physisorption of only NH3, acetone, and ethanol remarkably modified the electronic properties of the diazine monolayer, especially for the obvious change in electric conductivity, showing that the diazine monolayer is highly sensitive to acetone, NH3, and ethanol. Further, the adsorption of NH3, acetone, and ethanol molecules remarkably modifies, in varying degrees, the optical properties of the diazine monolayer, such as work function, absorption coefficient, and the reflectivity, whereas adsorption of other molecules has infinitesimal influence. The different adsorption behaviors and influences of the electronic and optical properties of molecules on the monolayer show that the diazine monolayer has high selectivity to NH3, acetone, and ethanol. The recovery time of NH3, acetone, and ethanol molecules is, respectively, 1.2 μs, 7.7 μs, and 0.11 ms at 300 K. Thus, the diazine monolayer has a high application potential as a room-temperature acetone, ethanol, and NH3 sensor with high performance (high selectivity and sensitivity, and rapid recovery time).

Design of high-sensitivity ethanol sensor based on Pr-doped SnO2 hollow beaded tubular nanostructure

Pr-doped SnO2 hollow beaded tubular nanostructure was synthesized by electrospinning technique, accompanied by using carbon spheres as sacrificial templates. The crystalline phase, morphology, microstructure, and element composition of the samples were explored and analyzed. The gas sensitivity test results show that Pr-doped SnO2 sensor exhibits high response value, excellent selectivity and rapid response-recovery ability to ethanol at 200 °C. The sensor can effectively detect ethanol vapor as low as 2 ppm. Response/recovery time to 100 ppm ethanol are about 12 s/8 s, respectively. The possible enhancement mechanism caused by the synergistic effect of the unique nanostructure, the carbon templates, and Pr dopant are discussed. The research may provide a better design of ethanol sensors.

Study of MWCNT / SnO2/Ru thick-film sensors for detecting the presence of certain harmful gases in air

Thick-film VOCs sensors based on ruthenated multi-walled carbon nanotubes coated with tin-dioxide nanoparticles (MWCNTs/SnO2) nanocomposite structures are prepared using three methods: hydrothermal synthesis, sol–gel technique and their combined method. It is shown that the optimal conditions for applications as acetone and toluene as well as ethanol and methanol vapors sensors in view of high response and selectivity relative to each other depend on choice of material synthesis method, mass ratio of the nanocomposite components and selected operating temperature. Selective sensitivity to acetone and toluene vapors at 150oC operating temperature MWCNTs/SnO2 are shown sensor structures with the mass ratio of the components 1:4 and 1:24, respectively. The samples with 1:200 mass ratio of the nanocomposite components are shown the selective response to acetone vapor exposure in the range of 200-250oC operating temperatures. The high sensitivity to ethanol and methanol vapors at 200oC operating temperature was revealed for the sensor structures made by different methods with the 1:8, 1:24, 1:50 and 1:66 ratios of the components, respectively. The results of research works related to the study of thick-film multiwall carbon nanotube– tin oxide nanocomposite sensors of propylene glycol (PG), dimethylformamide (DMF) and formaldehyde (FA) vapors are also presented in this paper. Investigations of response–recovery characteristics in the 50–300oC operating temperature range reveal that the optimal operating temperature for PG, DMF and FA vapor sensors, taking into account both high response and acceptable response and recovery times are about 200 and 220oC, respectively. The dependence of the sensor response on gas concentration is linear in all cases. Minimal propylene glycol, dimethylformamide and formaldehyde gas concentrations, where the perceptible signal was noticed, were 13, 5 and 115 ppm, respectively.

Ultrasensitive Sensors Based on PdO@SrFe2O4 Nanosphere-Modified Fibers for Real-Time Monitoring of Ethanol Gas

Spinel ferrites have attracted great interest in the research of sensing materials due to their excellent catalytic activity and flexible and tunable physical properties. Here, we report an environmentally friendly technique using an electrospinning system, followed by a hydrothermal method, to fabricate a highly sensitive ethanol sensor based on PdO nanosphere-modified SrFe2O4 fibers for real-time monitoring. From the evaluation of SEM, TEM, XRD, XPS, and BET, it is clear that the PdO nanospheres firmly adhere to the surfaces of SrFe2O4 fibers, which are composed of smaller grains and have a large surface area with a huge amount of adsorbed oxygen species. Comparison of the sensing performance of different amounts of loaded PdO nanospheres into SrFe2O4 fibers shows that the sensor C-2 based PdO@SrFe2O4 composite shows high selectivity for ethanol over other interfering gases with a high sensitivity of 16.4 at a relatively low temperature of 150 °C toward 20 ppm ethanol with fast response/recovery speed (13 s/20 s) and a low detection limit (100 ppb). Through long-term studies, it was found that the sensor was stable over a period of 60 days. Consequently, the superior sensing selectivity of C-2 based PdO@SrFe2O4 composite toward ethanol gas is attributed to the loading of PdO nanospheres into SrFe2O4 fibers, which could be effective due to charge transmission, spillover influence, and Fermi energy transferals as well as a huge surface area, and heterojunction impact can stimulate faster gas transmission kinetics and generate more catalytic spots on the surface of the sensing material. This research presents a general method for monitoring volatile organic pollutants with an ultrasensitive sensor based on spinel ferrites modified by noble metal oxide.

Calibration of Metal Oxide Semiconductor Gas Sensors by High School Students

A wide range of pollutants cannot be perceived with human senses, which is why the use of gas sensors is indispensable for an objective assessment of air quality. Since many pollutants are both odorless and colorless, there is a lack of awareness, in particular among students. The project SUSmobil (funded by DBU – Deutsche Bundesstiftung Umwelt) aims to change this. In three modules on the topic of gas sensors and air quality, the students (a) learn the functionality of a metal oxide semiconductor (MOS) gas sensor, (b) perform a calibration process and (c) carry out environmental measurements with calibrated sensors. Based on these introductory experiments, the students are encouraged to develop their own environmental questions. In this paper, the student experiment for the calibration of a MOS gas sensor for ethanol is discussed. The experiment, designed as an HTML-based learning, addresses both theoretical and practical aspects of a typical sensor calibration process, consisting of data acquisition, feature extraction and model generation. In this example, machine learning is used for generating the evaluation model as existing physical models are not sufficiently exact.

금속-유기 골격체 열분해를 통해 합성된 Co3O4/CoFe2O4 첨가 In2O3나노섬유를 이용한 고감도 고선택성 에탄올 센서

금속-유기 골격체 열분해를 통해 합성된 Co3O4/CoFe2O4 첨가 In2O3나노섬유를 이용한 고감도 고선택성 에탄올 센서

Facile synthesis of Pd@ZnO core@shell nanoparticles for selective ethanol detection

In this work, we reported a high-performance ethanol gas sensor based on novel Pd@ZnO core@shell nanoparticles (CSNPs). The Pd@ZnO CSNPs were synthesized by chemical method and characterized by XRD, TEM and EDS techniques. Gas sensing results demonstrated that Pd@ZnO CSNPs show high sensitivity and remarkable selectivity towards ethanol at 250 °C. The response value of Pd@ZnO CSNPs is 152, which is almost six times higher than the response value (27) of ZnO NPs at 250 °C. The mechanism of enhancement in sensing properties can be ascribed to the chemical and electronic sensitization effect of Pd NPs and also due to the unique core@shell structure. These characteristics may shed light on the development of a selective ethanol sensor based on Pd@ZnO CSNPs.

Fuel Economy and Emissions of E85 in Passenger Cars - A Move towards Flex Fuel Vehicle

<div class="section abstract"><div class="htmlview paragraph">Many countries are developing strategies to curb the consumption of fossil fuels, and to increase the share of alternative fuels such as alcohols, natural gas, fuel cell and electricity in the energy pool in order to improve energy security and reduce atmospheric pollution. Alcohol fuels are promising one and it has been widely used in many countries as blending component for gasoline. Ethanol has a high-octane number but it has a lower calorific value than gasoline. The performance of engine may be affected with higher percentage of ethanol in gasoline due to demand for larger quantity of fuel that could not be supplied by vehicles which are tuned to run on gasoline only. In this study, a second electronic control unit (ECU) was installed in series with the existing commercial or primary ECU and an ethanol sensor was installed in the fuel line. This secondary ECU modulates the fuel injection pulse width of the primary ECU depending on ethanol concentration in the fuel. The vehicle studies were carried out using Indian automotive gasoline meeting IS:2796 specification and 85% ethanol blended gasoline (E85) in a climatically controlled chassis dynamometer lab in which test cell temperature maintained at 25±1 °C throughout the test. Modified Indian Driving Cycle tests (MIDC) and constant speed tests were carried out using E85 and commercial gasoline to investigate the fuel economy, gaseous mass emissions, particulate emission in terms number and size characteristics. Gaseous emission was reduced up to 30% with the penalty of reduction in fuel economy by approximately 30% over the MIDC. The vehicle power was maintained while using both fuels at respective constant speeds during the road load simulation cycles however an increase in fuel consumption was observed with E85. The tailpipe exhaust particle emission measurement had shown up to 50% reduction in exhaust particulate emissions with E85. This study demonstrates the potential of using higher blends of ethanol up to E85 and meeting power or speed demand at constant speeds and driving cycle tests.</div></div>

Ultrathin ternary metal oxide Bi2MoO6 nanosheets for high performance asymmetric supercapacitor and gas sensor applications

Two dimensional (2-D), unstacked Bi2MoO6 nanosheets are directly grown on nickel foam and prepared as powder via easy, template-free hydrothermal route. The prepared material was systematically characterized using techniques viz XRD, Cs-TEM, HRTEM, FESEM, XPS, elemental mapping, EDS. Bi2MoO6 nanosheets grown on Nickel foam employed for supercapacitor application, whereas powder form was utilized to fabricate ethanol sensor. The electrochemical characteristics viz cyclic voltammetry (CV), galvanic charging-discharging (GCD), and electrochemical impedance spectroscopy (EIS) were investigated for Bi2MoO6 nanosheets grown nickel foam in 1 M KOH aqueous solution within −0.2 to 0.8 V potential window. The areal capacitance of 655.5 mF/cm2 was achieved at 1 mA/cm2 current density with the energy density of 22.76 × 10−3 Wh/cm2 and 347.18 × 10−3 W/cm2 power density. The 5000 charge–discharge cycles were performed with excellent capacitance retention. The Bi2MoO6 sensor was tested for 10–100 ppm ethanol. A high response of 82% was noted for 100 ppm ethanol concentration at 275 °C. The dynamic resistance response, selectivity, and sensor’s stability were tested and analysed.

Chemically synthesized ZnO and Cd-ZnO thick films as Ethanol sensor

In this paper, we report precipitation method for preparation of pure and Cd-ZnO nanorod using different doing concentration. Thick films are fabricated by screen printing technique. For structural, morphological, compositional and optical characteristics of fabricated thick films X-ray diffraction technique (XRD), field-emission scanning electron microscopy (FESEM), energy dispersive X-ray technique and UV–visible spectroscopy were used. To check gas sensing properties, hydrogen sulphide (H2S), carbon dioxide (CO2), liquid petroleum gas (LPG), ammonia vapour (NH3), ethanol vapour and hydrogen (H2) gases were used. The excellent gas response was obtained for 3.0 wt.% Cd-ZnO towards ethanol among all Cd-ZnO thick films at operating temperature 573 °K.

Design of highly sensitive and selective ethanol sensor based on α-Fe2O3/Nb2O5 heterostructure

The introduction of heterostructures is a new approach in gas sensing due to their easy and quick transport of charges. Herein, facile hydrothermal and solid-state techniques are employed to synthesize an α-Fe2O3/Nb2O5 heterostructure. The morphology, microstructure, crystallinity and surface composition of the synthesized heterostructures are investigated by scanning electron microscope, transmission electron microscope, x-ray diffraction, x-ray photoelectron spectroscopy and Brunauer–Emmett–Teller analyses. The successful fabrication of the heterostructures was achieved via the mutual incorporation of α-Fe2O3 nanorods with Nb2O5 interconnected nanoparticles (INPs). A sensor based on the α-Fe2O3(0.09)/Nb2O5 heterostructure with a high surface area exhibited enhanced gas-sensing features, maintaining high selectivity and sensitivity, and a considerable recovery percentage towards ethanol gas. The sensing response of the α-Fe2O3(0.09)/Nb2O5 heterostructure at lower operating temperature (160 °C) is around nine times higher than a pure Nb2O5 (INP) sensor at 180 °C with the flow of 100 ppm ethanol gas. The sensors also show excellent selectivity, good long-term stability and a rapid response/recovery time (8s/2s, respectively) to ethanol. The superior electronic conductivity and upgraded sensitivity performance of gas sensors based on the α-Fe2O3(0.09)/Nb2O5 heterostructure are attributed due to its unique structural features, high specific surface area and the synergic effect of the n–n heterojunction. The promising results demonstrate the potential application of the α-Fe2O3(0.09)/Nb2O5 heterostructure as a good sensing material for the fabrication of ethanol sensors.

Flexible Ethanol Sensor Based on ZnO-Based Nanomaterials Prepared by Hydrothermal Method

Metal oxide semiconductor ethanol sensor is widely used in alcohol driving detection, biomedical and industrial fields. As a typical n-type semiconductor, ZnO has a certain response to ethanol at a certain temperature, but there is still a large room for improvement in gas sensing characteristics such as sensitivity, response and recovery time, selectivity and so on. In this paper, the orthogonal experiment is used to design the experiment. Taking the hydrothermal reaction time, hydrothermal reaction temperature and the molar ratio of zinc oxide to thiourea as the three important variables in the orthogonal experiment, nine groups of representative ZnO-ZnS powder samples with different process combinations are prepared by hydrothermal method. The structure and morphology of the nine samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Energy Dispersive Spectrometer (EDS). The optimal preparation scheme of ZnO-ZnS is selected, and the sensor based on polyimide is integrated. The gas sensing characteristics of ZnO-ZnS and pure ZnO sensors are tested by static gas distribution method. The results show that ZnO-ZnS nano materials have good sensitivity to ethanol, and the sensitivity to 100 ppm ethanol gas is 67.35 at 300 °C, and the response and recovery time is about 15 seconds. The prepared flexible sensor also shows good selectivity and stability, which provides a reference for the preparation of high-performance flexible ethanol sensor in the future test.

Ultra Responsive and Highly Selective Ethanol Gas Sensor Based on Au Nanoparticles Embedded ZnO Hierarchical Structures

Ultra sensitive and highly selective sensor towards ethanol (C2H5OH) vapor was developed from Au embedded open space ZnO hierarchical nanostructures. The ethanol sensing behaviors were examined at different working temperatures and various quantities of Au nanoparticles as the variable. The response of the Au/ZnO nanostructure based sensor at the optimal working temperature of 220 °C towards ethanol vapor is 167 times higher than that of the pristine ZnO structure at the optimal working temperature of 260 °C. In addition, the developed sensor exhibited excellent selectivity to ethanol compared with other vapors such as methanol, acetone, 2-propanol and toluene. The ethanol sensing mechanism of the Au embedded ZnO sensor structure is also proposed. The morphology and characteristics of the fabricated samples were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and electrical measurements. This finding offers a new way of thinking for the design and development of ethanol sensors based on Au nanoparticles embedded ZnO hierarchical structures.

Ultra-high response ethanol sensors from fully-printed co-continuous and mesoporous tin oxide thin films

Printed vapor and moisture sensors are essential components of the multi-sensor platforms that the pharmaceutical and food safety industries require in large quantities; however, fully-printed gas or volatile organic compounds (VOCs) sensors have rarely been reported in the literature. In this regard, we demonstrate the fabrication of high surface-to-volume ratio co-continuous mesoporous tin oxide based fully-printed chemiresistive-type ethanol gas sensors. Herein, a soft templating method that mimic evaporation induced self-assembly (EISA) process has been utilized with amphiphilic triblock co-polymer pluronic F127 (PEO106-PPO70-PEO106) as the templating agent and a low-cost swelling agent ´xylene´ as the micelle expander to obtain pore diameter in the range of 10–25 nm. The tuned pore size at this range is found optimal for high surface area and high pore volumes, at the same time. The fully-printed ethanol sensors fabricated with such mesoporous SnO2 active elements show highly selective sensitivity towards ethanol with an average response of 1050 for 100 ppm and a very short response and recovery time of 9 and 129 s, respectively. The observed high response can be attributed to the high density and easily accessible active sites and simultaneous high mobility electron transport through the well-crystalline and co-connected tin oxide ligaments.