Low Concentrations Of Acetone Research Articles

The effect of ferredoxin in enhancing the sensing properties of chitosan based acetone sensors

The purpose of this study is to investigate the effect of ferredoxin on sensing properties of chitosan-based acetone sensors. The composites were facilely prepared and their sensing properties toward low concentration of acetone have been investigated at room temperature. The improvement of electrical and physical conditions of the sensors has been successfully carried out by blending ferredoxin into chitosan solution for fabrication of ferredoxin-chitosan based acetone sensors. Electrochemical deposition method has been chosen to fabricate the sensors. The ratio of ferredoxin to chitosan was varied at 5:95, 10:90, 15:85 and 20:80. The sensors were exposed to acetone vapour with acetone concentrations of 0.1, 1, 10, 20, 50, and 100 ppm. Among the sensors, 15% ferredoxin-chitosan based acetone sensor exhibited the highest response. The response of the sensor is higher 20% than chitosan-based acetone sensors. The surface roughness of sensor was smoother compared to that of chitosan -based acetone sensors.

Bimetal PdAu decorated SnO2 nanosheets based gas sensor with temperature-dependent dual selectivity for detecting formaldehyde and acetone

In this study, SnO2 nanosheets (NSs) was firstly prepared by the hydro-solvothermal treatment, and then decorated with Pd, Au and PdAu bimetallic nanoparticles (NPs) by an in situ reduction with ascorbic acid (AA). Their morphology, chemistry, and crystal structure were characterized at the nanoscale. It was found that SnO2 NSs were flower-like with thickness of 7–12 nm, and PdAu NPs with the size of 3–10 nm were dispersed uniformly on the surface of SnO2 NSs. Their gas sensing properties were carefully studied. The results demonstrated that the PdAu/SnO2 sensor can not only effectively detect acetone at 250 °C with response of 6.6 to 2 ppm acetone, but also detect formaldehyde at 110 °C with response of 4.1–2 ppm formaldehyde, and the corresponding detection limit is as low as 45 ppb and 30 ppb, respectively. Moreover, the PdAu/SnO2 sensor exhibited excellent reusability, and reliability to the low concentration of acetone and good anti-interference to humidity and other biomarkers in human breath. Compared with that decorated with their parent metal (Pd or Au), the enhanced response of SnO2 NSs decorated with PdAu bimetallic NPs may be ascribed to the chemical sensitization of Au, the electronic sensitization of Pd and the synergistic effect of PdAu bimetallic NPs. The PdAu/SnO2 sensor has a great potential application in detecting formaldehyde and diabetes diagnosis.

Acetone gas sensor based on iron molybdate nanoparticles prepared by hydrothermal method with PVP as surfactant

The Fe2(MoO4)3 nanoparticles were prepared by hydrothermal method using polyvinyl pyrrolidone (PVP) as surfactant. The crystal phase, morphology and microstructure were characterized by x-ray diffraction, scanning electron microscopy. The results indicated the Fe2(MoO4)3 nanoparticles were composed of sphere-like monoclinic nanocrystals with average size of 50 nm. The sensor based on the Fe2(MoO4)3 nanoparticles exhibits good gas-sensing performances, especially to acetone. The response to acetone was significantly higher than that to other gases. The responses of the sensor were 2.45, 24.7, respectively, to 1 ppm and 100 ppm acetone at the optimal operating temperature of 340 °C. The Fe2(MoO4)3 nanoparticles can be potential material for high response and low concentration acetone selective sensor which can be applied in diabetes diagnosis.

A novel conductometric sensor based on hierarchical self-assembly nanoparticles Sm2O3 for VOCs monitoring

Hierarchical self-assembly structured Sm2O3 nanoparticles were prepared by a simple and cost effective hydrothermal method and subsequent annealing at 800 °C in air. The size, shape and phase composition of the structures synthesized by changing the hydrothermal processing time were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-Raman and photoluminescence (PL) analysis. Upon varying the timing of hydrothermal process (from 24 to 36 h) SEM analysis highlighted differences in the aggregation and coalescence of particles. XRD patterns revealed their crystalline nature while from Raman active modes the C-type structure of cubic Sm2O3 was confirmed. Sensor performances of the synthesized Sm2O3 nanostructures have been investigated for the monitoring of two important volatile organic compounds (VOCs) such as ethanol and acetone. The sensitivity, selectivity and response repeatability of the fabricated conductometric sensors were reported for the first time. Results demonstrate that Sm2O3 nanoparticles are effective in the monitoring of low concentration of both acetone and ethanol in air.

Transilient Response to Acetone Gas Using the Interlocking p+n Field-Effect Transistor Circuit.

Low concentration acetone gas detection is significantly important for diabetes diagnosis as 1.8–10 ppm of acetone exists in exhaled breath from diabetes patients. A new interlocking p+n field-effect transistor (FET) circuit has been proposed for Mn-doped ZnO nanoparticles (MZO) to detect the acetone gas at low concentration, especially close to 1.8 ppm. It is noteworthy that MZO in this interlocking amplification circuit shows a low voltage signal of <0.3 V to the acetone <2 ppm while it displays a transilient response with voltage signal >4.0 V to >2 ppm acetone. In other words, the response to acetone from 1 ppm to 2 ppm increases by ~1233%, which is competent to separate diabetic patients from healthy people. Moreover, the response to 2 ppm acetone is hardly influenced by high relative humidity of 85%. In the meanwhile, MZO in this interlocking circuit possesses a high acetone selectivity compared to formaldehyde, acetaldehyde, toluene and ethanol, suggesting a promising technology for the widespread qualitative screening of diabetes. Importantly, this interlocking circuit is also applicable to other types of metal oxide semiconductor gas sensors. The resistance jump of p- and n-FETs induced by the change of their gate voltages is deemed to make this interlocking circuit produce the transilient response.

Solvent-Induced Crystal Polymorphism as Studied by Pyroelectric Measurements and Impedance Spectroscopy: Alcohols as Tailor-Made Inhibitors of α-Glycine.

Metastable polymorphs commonly emerge when the formation of the stable analogues is inhibited by using different solvents or auxiliaries. Herein, we report that when glycine is grown in aqueous solutions in the presence of low concentrations of different co-solvents, only alcohols and acetone, unlike water and acetic acid, are selectively incorporated in minute amounts within the bulk of the α-polymorph. These findings demonstrate that although water binds more strongly to the growing face of the crystal, alcohols and acetone are exclusively incorporated, and thus serve as efficient inhibitors of this polymorph, leading to the precipitation of the β-form. These solvents then create polar domains detectable by pyroelectric measurements and impedance spectroscopy. These results suggest that in the control of crystal polymorphism with co-solvents, one should consider also the different desolvation rates in addition to the energy of binding to the growing faces of the crystal.

MOF-derived porous ZnO/Co3O4 nanocomposites for high performance acetone gas sensing

We report a facile strategy to synthesize porous ZnO/Co3O4 composites by direct pyrolysis of the metal–organic frameworks (MOFs) precursor and their applications to the sensing of acetone at ppb–ppm level. The as-prepared ZnO/Co3O4 sample exhibits enhanced sensitivity (15.17 ppm−1), high selectivity towards low-concentration acetone when compared with pure ZnO. The enhancement in gas sensing performance of ZnO/Co3O4 sample could be attributed to the unique porous structure, the p-Co3O4/n-ZnO junctions effect and the catalytic activity of Co3O4. The studies might open intriguing perspectives for the design of porous p/n composites for high performance gas sensing applications.

Prussian Blue analogue derived porous NiFe2O4 nanocubes for low-concentration acetone sensing at low working temperature

Real-time detection of acetone vapor at low concentration plays a decisive role in early noninvasive diagnosis of diabetes. In this work, porous NiFe2O4 crystalline nanocubes have been scalably prepared via an as-developed cost-efficient and facile strategy, which involves a morphology-inherited annealing treatment of single-resource Prussian Blue analogue of Ni3[Fe(CN)6]2·xH2O solid nanocubes as self-sacrificial templates. The porous NiFe2O4 crystalline nanocubes are demonstrated to be composed of primary nano building blocks and interconnected pores. When utilized as sensing materials, the as-synthesized NiFe2O4 exhibited p-type gas-sensing behavior that the resistance increases in a reducing gas atmosphere. Furthermore, the as-fabricated NiFe2O4 sensor was sensitive and selective to acetone gas with an obvious response value of 1.9 at its low concentration (1 ppm) and low detection of limit (0.52 ppm) at a quite low working temperature (160 °C). In addition, the sensing mechanism is deeply investigated. More significantly, our prominent findings herein shed light on the fabrication of metal oxide based gas sensors in environmental and medicinal fields.

Liquid crystal/polymer fiber mats as sensitive chemical sensors

We present quantitative measurements of the optical response of liquid crystal (LC)/polymer composite fiber mats to toluene and acetone vapors. Our analyses in comparison with control measurements of pure LC film and polymer fiber mats show that the chemicals can pass through the polymer sheath of the fibers and be absorbed by the LC in the core. This absorption changes the optical properties of the fiber mats which can be used to produce sensitive and reversible detection. The sensitive response at low concentrations of both acetone and toluene demonstrates the feasibility of using these fibers for highly sensitive and specific sensors for volatile organic compound detection.

Modified Polysulfone Ultrafiltration Membrane for Humic Acid Removal During Peat Water Treatment

In this research, UF membrane was prepared by blending polysulfone (PSf) in DMAc with the addition of PEG400 and low concentration of acetone as additives. The effect of PSf/PEG400 and polymer/solvent ratio on the performance of PSf membrane was investigated during two hours of peat water filtration. The results showed that the increase of ratio PSF/PEG400 from 1:1 to 1:2.5 improved the membrane hydrophilicity. It was indicated by a decrease of water contact angle from 62° to 33° and increased water content in membrane structure from 65 to 74,5%. In addition, the pure water flux also increased up to 200 times. A stable flux is achieved when the ratio PSf/PEG is 1:2 and resulted in 84% rejection of humic acid. The increase of polymer concentration in the membrane solution reduced the pure water flux but increased the rejection of humic acid. Higher polymer concentration in membrane solution reduced fouling tendency towards the membrane surface. It showed that flux decline was reduced from 60% to 40% when the ratio of polymer/solvent concentration was changed from 40/60 to 50/50.

Low concentration acetone gas sensing properties of 3 wt% Pd-doped SmCoxFe1-xO3 nanocrystalline powders under UV light illumination

3 wt% Pd-doped SmCoxFe1-xO3 nanocrystalline powders were prepared by the sol-gel method and annealed at 750 °C. The sensing response of Pd:SmCo0.1Fe0.9O3 was measured to be 1.62, 1.85, 2.21, 2.59, 3.69, 8.48, and 13.86 for 0.01, 0.02, 0.05, 0.1, 0.2, 0.5 and 1 ppm acetone gas, respectively, at an optimal operating temperature of 220 °C. The response and recovery times following exposure to 0.5 ppm acetone gas were 32 s and 13 s, respectively. To decrease the optimal operating temperature, UV light illumination at a wavelength of 365 nm was introduced. Under the UV light, the response showed a large improvement to 1.98, 2.53, 3.68, 5.03, 7.68, 10.31, and 15.85 for the same acetone gas concentrations, respectively, at an optimal operating temperature of 160 °C. Pd:SmCoxFe1-xO3 can be used to distinguish between healthy individuals and possible diabetic patients. Exhaled breath from four volunteers was detected under UV-light illumination. The resulting data show that the exhaled breath from diabetics contained more than 1 ppm acetone gas, while approximately 0.2 ppm acetone gas was detected in the exhaled breath from healthy individuals.

SnO2 decorated SiO2 chemical sensors: Enhanced sensing performance toward ethanol and acetone

SnO2 decorated SiO2 chemical sensors with different Sn/Si ratios were synthesized by micro-emulsion followed by ultrasonic-assisted deposition-precipitation method and used for highly sensitive and selective detection of ethanol and acetone. XRD, EDS, SEM, and TEM were used to characterize the samples. The results confirm deposition of small crystalline tin oxide particles on the surface of silica particles. Using these formed materials for detection of ethanol and acetone resulted in significant enhancement of the sensitivity and reducing temperature of maximum response in comparison to the pure SnO2. The selectivity of the sample with the highest sensitivity to ethanol and acetone, i.e. 80wt% SnO2/SiO2, was examined by measuring its sensitivity to some interfering gases including carbon monoxide, methane, toluene, Trichloroethylene (TCE) and propane; the results showed very high selectivity of the sensor to ethanol and acetone, especially at low temperatures. The sensor responses to traces of acetone in the air with the concentration ranging from 0.5 to 5ppm at different temperatures of 70, 170 and 270, and 370°C were measured to evaluate the capability of the sensor for detection of acetone in the breath of human, which is helpful in the diabetes diagnosis. The sensor could effectively show high enough sensitivity even to these very low concentrations of acetone which reveals its high potential for being used in acetone detection devices. Finally, the effect of humidity on the sensitivity of sensor to acetone was investigated. Increasing the humidity of background air, caused the sensor response to decrease and the operating temperature of maximum response of the sensor to increase.

Controllable synthesis of hierarchical MnOx/TiO2 composite nanofibers for complete oxidation of low-concentration acetone

A novel hierarchical MnOx/TiO2 composite nanofiber was fabricated by combining the electrospinning technique and hydrothermal growth method. The synthesized nanomaterial, which comprised primary TiO2 nanofibers and secondary MnOx nanoneedles, was further investigated for complete catalytic oxidation of volatile organic compounds for the first time, and this presented high-oxidation performance on low-concentration acetone. The morphological, structural, physicochemical characterization, and catalytic performance analyses demonstrated that the highest catalytic activity was achieved from the obtained MnOx/TiO2 nanofiber catalyst with 30wt.% manganese loading. This finding can be ascribed to the synergistic effect of the specific hierarchical nanofibrous morphology, the abundant surface-adsorbed oxygen, the superior redox property, and the sufficient specific surface.

Transparent gas senor and photodetector based on Al doped ZnO nanowires synthesized on glass substrate

In this work high density, well-aligned Al doped ZnO (AZO) nanowires are hydrothermally synthesized on glass substrate at 99°C. The Al content is ~1.57at%. The PL spectrum shows that Al impurities caused an increase in the number of oxygen vacancies. The spectral response results show that the maximum responsivity and quantum efficiencies η of AZO NWs are 3.61A/W and 84.9%, at an incident light wavelength of 360nm. These AZO NWs have less humidity sensitivity, thus decreasing the effect of humidity effect on gas sensing. Low gas concentrations of 10ppm ethanol and 10ppm acetone can be detected with good responses of 24.5% and 21.2%, using the AZO NW sensor at 200°C and with 0.1V applied bias.

Porous Au/ZnO nanoparticles synthesised through a metal organic framework (MOF) route for enhanced acetone gas-sensing

Porous Au/ZnO nanoparticles through a simple metal organic framework route show high response and selectivity towards low concentration acetone.

Synthesis of novel ZnSnO3 hollow polyhedrons with open nanoholes: Enhanced acetone-sensing performance

A kind of novel ZnSnO3 hollow polyhedrons with open nanoholes was synthesized via facile hydrothermal method and characterized by X-ray diffraction (XRD), energy dispersive X-Ray spectroscopy (EDX), scanning electronmicroscopy (SEM) and transmission electron microscopy (TEM) analyses. A possible formation mechanism of such microstructure was speculated. Moreover, the sensor based on these ZnSnO3 hollow polyhedrons exhibited good gas sensing performance at 240°C to 50ppm acetone, and the response and recovery times were about 17 and 10s, respectively. The significant decrease in optimal operating temperature and the ability of detecting low-concentration acetone gas were attributed to the unique structure of the products which possessed hollow interior and good-permeation surface.

Anatase TiO2 hierarchical microspheres consisting of truncated nanothorns and their structurally enhanced gas sensing performance

Anatase TiO2 hierarchical microspheres were synthesized by a facile hydrothermal method. Characterization results indicated that the microspheres were consisted of massively aggregative nanothorns with truncated tips, which had exposed {001} and {101} crystal facets, and there were abundant mesoporous structures in the microspheres. A possible growth model of the TiO2 hierarchical microspheres was put forward based on a series of experimental analysis. When used for gas sensing, it was found that the TiO2 hierarchical microspheres showed a distinct high sensitivity towards acetone, the optimal response to 100 ppm acetone was 14.6, which was much higher than that of other materials reported in previous works. Moreover, the TiO2 hierarchical microspheres exhibited a fast response/recovery speeds (<10 s), a low detection limit (the response still reaches 6.1 even at a low acetone concentration of 10 ppm) and an excellent selectivity. Through systematical analysis, it can be concluded that the enhancement of gas sensing performance of the TiO2 hierarchical microspheres was ascribed to its unique structural features (perfect hierarchical mesoporous structure as well as specific crystal facets exposing), which could be described as structurally enhanced gas sensing performance. The present results encourage us to further investigate crystal facets-dependent gas sensing properties of TiO2 for the designing of conductometric gas sensors with better sensing performance.

Hydrothermal Synthesis of ZnO Structures Formed by High-Aspect-Ratio Nanowires for Acetone Detection.

Snowflake-like ZnO structures originating from self-assembled nanowires were prepared by a low-temperature aqueous solution method. The as-grown hierarchical ZnO structures were investigated by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM). The results showed that the snowflake-like ZnO structures were composed of high-aspect-ratio nanowires. Furthermore, gas-sensing properties to various testing gases of 10 and 50 ppm were measured, which confirms that the ZnO structures were of good selectivity and response to acetone and could serve for acetone sensor to detect low-concentration acetone.

Partial substitution of manganese with cerium in SrMnO3 nano-perovskite catalyst. Effect of the modification on the catalytic combustion of dilute acetone

Ultrafine SrMn1−xCexO3 (x = 0, 0.2) perovskites were prepared by self-combustion method and heat treatment at 1000 °C for 4 h. The structure and surface properties were investigated by X-ray powder diffraction, scanning electron microscopy (SEM), EDX spectroscopy, and BET analysis. The catalyst properties of the perovskite nanopowders were tested in the catalytic combustion of dilute acetone at atmospheric pressure. The results revealed that the partial substitution of Mn by Ce ions (x = 0.2) in perovskite structure of SrMnO3 had significantly improved catalytic activity of the perovskite. The SrMn0.8Ce0,2O3 perovskite composition can be a good candidate for catalytic combustion of low concentration acetone (1–2‰ in air) at low temperatures. The acetone conversion over this catalyst exceeds 90% at 200 °C, whereas over SrMnO3 it is only 50%. Compared with SrMnO3, T50 is decreased by 75 °C and T90 is decreased by 70 °C. The enhancement of the catalytic activity at a Ce doping of 0.2 may be ascribed to smaller crystallite sizes, larger specific surface area and the presence of Ce and Mn cations with variable valence in the perovskite structure.

Sensing performances to low concentration acetone for palladium doped LaFeO3 sensors

The PdCl2 was mixed with nanocrystalline powders LaFeO3 and subsequently followed by an annealing of 800 °C. PdO phase was formed and almost distributed uniformly on the surface of LaFeO3 nano-particles. With an increase of PdO amounts in composite powders, sensing sensitivity Rg/Ra to low concentration acetone or ethanol for Pd doped LaFeO3 sensors increased at first, underwent the maximum with 2 wt.% PdCl2 dopant, and then doped again. Interestingly, appropriate Pd doping in LaFeO3 changed the selectivity behavior of gas sensing. LaFeO3 sensor showed good selectivity to ethanol, but 2 wt.% Pd doped LaFeO3 sensor showed good selectivity to acetone. The sensitivity for LaFeO3 at 200 °C was 1.32 to 1 ppm ethanol, and 1.19 to 1 ppm acetone. Whereas the sensitivity for 2 wt.% Pd doped LaFeO3 at 200 °C was 1.53 to 1 ppm ethanol, and 1.9 to 1 ppm acetone. The 2 wt.% Pd doped LaFeO3 sensor at 200 °C showed very short response time (4 s) and recovery time (2 s) to 1 ppm acetone gas, respectively. Such results showed that 2 wt.% Pd doped LaFeO3 sensor is a new promising sensing candidate for detecting low concentration acetone.