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Abstract: This paper focuses on the gas sensing properties of the mixed-potential-type NO2 sensor based on yttria stabilized zirconia (YSZ) and NiO electrode. The sensing performance of the sensor was improved by modifying the three-phase boundary (TPB). Hydrofluoric acid with different concentrations (10%, 20% and 40%) was used to corrode YSZ substrate to obtain large superficial area of TPB. The scanning electron microscope and atomic force microscopic images showed that the 40% HF could form the largest superficial area at the same corroding time (3h). The sensitivity of the sensor using the YSZ plate corroded with 40% hydrofluoric acid to 20–500ppm NO2 was 76mV/decade at 850°C, which was the largest among the examined HF concentrations. It was also seen that the sensor showed a good selectivity and speedy response kinetics to NO2. On the basis of the measurements of anodic and cathodic polarization curves, as well as the complex impedance of the device, the sensing mechanism was confirmed to involve a mixed potential at the oxide sensing electrode. [Copyright &y& Elsevier]

Abstract: A compact tubular sensor based on NASICON (sodium super ionic conductor) and porous Cr2O3 sensing electrode was designed for the detection of ammonia. The sensor gave excellent sensing properties to 50–500ppm ammonia in air at 250–450°C. The EMF value of the sensor was almost proportional to the logarithm of ammonia concentration, the sensitivity (slope) was −89mV/decade at 350°C. It was also seen that the sensor showed a good selectivity to ammonia, and an excellent resistance to water vapor. The sensor had speedy response kinetics to ammonia, the 90% response time to 50ppm ammonia was 30s, and the recovery time was 60s. [Copyright &y& Elsevier]

Abstract: A compact tubular sensor based on NASICON (sodium super ionic conductor) and CaMg3(SiO3)4 (Asbestos, acid washed A.R)-doped CdS sensing electrode was prepared for the detection of chlorine. The sensing properties strongly depended on the sintered temperature of the sensing electrode materials. The sensor using CaMg3(SiO3)4-doped CdS sintered at 600 °C gave excellent sensing properties to 1–10 ppm chlorine in air at 100–250 °C. The sensitivity (slope) was 392 mV/decade at 200 °C. And it showed a good selectivity to Cl2 against H2S, SO2, NO2, NH3, CH4 and CO. Also it had speedy response kinetics to chlorine, the 90% response or 90% recovery time to 5 ppm chlorine was 20 s or 37 s, respectively. The phase compositions and grain size of NASICON and CaMg3(SiO3)4-doped CdS were examined by means of X-ray diffraction (XRD). On the basis of XPS analysis for Cl2-absorbed sensing electrode, a sensing mechanism involved the mixed potential at the sensing electrode was proposed. [Copyright &y& Elsevier]

Abstract: A compact tubular sensor based on NASICON (sodium super ionic conductor) and V2O5-doped TiO2 sensing electrode was designed for the detection of SO2. In order to reduce the size of the sensor, a thick-film of NASICON was formed on the outer surface of a small Al2O3 tube; furthermore, a thin layer of V2O5-doped TiO2 with nanometer size was attached on the NASICON as a sensing electrode. This paper investigated the influence of V2O5 doping and sintering temperature on the characteristics of the sensor. The sensor attached with 5wt% V2O5-doped TiO2 sintered at 600°C exhibited excellent sensing properties to 1–50ppm SO2 in air at 200–400°C. The EMF value of the sensor was almost proportional to the logarithm of SO2 concentration and the sensitivity (slope) was −78mV/decade at 300°C. It was also seen that the sensor showed a good selectivity to SO2 against NO, NO2, CH4, CO, NH3 and CO2. Moreover, the sensor had speedy response kinetics to SO2 too, the 90% response time to 50ppm SO2 was 10s, and the recovery time was 35s. On the basis of XPS analysis for the SO2-adsorbed sensing electrode, a sensing mechanism involving the mixed potential at the sensing electrode was proposed. [Copyright &y& Elsevier]

Abstract: A compact tubular sensor based on sodium super ionic conductor (NASICON) and Pr6O11-doped SnO2 sensing electrode was designed for the detection of H2S. In order to reduce the size of the sensor, a thick film of NASICON was formed on the outer surface of a small Al2O3 tube; furthermore, a thin layer of SnO2 with nanometer size was attached on the NASICON as a sensing electrode. Compared with pure SnO2, Pr6O11-doped SnO2 was found to be more suitable for the sensing electrode. The sensor using Pr6O11-doped SnO2 gave excellent sensing properties to 5–50ppm H2S in air at 200–400°C. The EMF value of the sensor was almost proportional to the logarithm of H2S concentration, the sensitivity (slope) was 74mV/decade at 300°C. It was also seen that the sensor showed a good selectivity to H2S against SO2, NO2, CH4 and CO, and an excellent resistance to water vapor. The sensor had speedy response kinetics to H2S, the 90% response time to 5, 20 and 50ppm H2S was 8, 6 and 4s, respectively, and the recovery time was 12, 18 and 30s, respectively. On the basis of XPS analysis for the H2S-adsorbed sensing electrode, a sensing mechanism involving the mixed potential at the sensing electrode was proposed. [Copyright &y& Elsevier]

[Display omitted] • Inspired by the nature, a sea urchin-like IL modified UiO-66 was obtained. • The optimized sensor exhibits high response and ultra-fast response speed in the low humidity range of 0–35% RH. • The sensing mechanism is fully investigated through DFT calculation. • The low humidity sensor was proved to have applications in visual humidity detection and water source location. Numerous applications require low humidity sensors that not only sensitive but also stable, small hysteresis, high resolution and fast response. However, most reported low humidity sensors cannot possess these properties at the same time. In this work, inspired by sea urchin, we developed an ionic liquid (IL) modified metal organic framework (UiO-66) based low humidity sensor. Owing to the synergistic effect of the hydrophilicity and ionic conductivity of IL and the steric hindrance effects of UiO-66, the optimized low humidity sensor simultaneously exhibits high response (47.5), small hysteresis (0.3 % RH), ultrafast response speed (0.2 s), high resolution (1 % RH), and excellent long-term stability (>120 days). In particular, the sensor has been proved to have potential applications in visual humidity detection and water source location. This work provides a preliminary design principle that will contribute to the preparation of high-performance low humidity sensing materials. [ABSTRACT FROM AUTHOR]

Hollow sphere composites were synthesized by a template-free hydrothermal method from MoO3 and In2O3. The spheres have a typical size of 800 ± 50 nm and were characterized by XRD, FESEM, TEM, XPS. Gas sensors based on samples with different Mo/In composite ratios were fabricated and their gas sensing properties were studied. The results show that a Mo:In ratio of 1:1 in the composite gives the highest response, typically at a working temperature of 250 °C. The response increases to 38 when exposed to 100 ppm acetone at 250 °C. This is 13.6 times better than when using pure MoO3. The sensor shows improved selectivity, response, repeatability and long-term stability. Typical features include a large specific surface area, and high levels of chemisorbed oxygen and defective oxygen sites. The N-N heterojunction theory was used to explain the improvement of gas sensing performance. [ABSTRACT FROM AUTHOR]

In this work, yttria-stabilized zirconia (YSZ) thin films were prepared by sol-gel and spin-coating methods, which are simple and inexpensive, with good film quality and excellent electrical conductivity. Using this film, a YSZ film mixed-potential type NO 2 gas sensor with NiO as the sensitive electrode material was fabricated. The films had the best dielectric properties when spin-coated four times, and the sensors had the highest response (48 mV–100 ppm NO 2) as well as the best sensitivity (14.8 mV/decade for 5–20 ppm NO 2 and 42 mV/decade for 20–500 ppm NO 2). The YSZ thin-film gas sensor operates at a lower temperature, with an optimum operating temperature of 550 °C, and the power consumption of the sensor has been reduced by approximately 46 % or more compared to conventional bulk YSZ NO 2 gas sensors. This provides a very effective direction for the low-power design of high-temperature devices such as the YSZ gas sensor. In addition, thin-film devices are more conducive to integrating sensors into microelectronic circuits, greatly improving the application scenarios for such devices. This sensor has excellent repeatability, very good selectivity, and outstanding long-term stability over 30 days of continuous measurement. In conclusion, based on the excellent sensing performance and low power consumption of the YSZ thin-film gas sensor, the sensor has a promising future for in-situ monitoring of NO x. [ABSTRACT FROM AUTHOR]

This study aimed to develop a H 2 S gas sensor based on gadolinia-doped ceria (GDC) solid electrolyte and Co 3 O 4 /ZnO/Y 2 O 3 ternary nanocomposite. Heterojunctions were formed inside the Co 3 O 4 /ZnO/Y 2 O 3 ternary nanocomposite sensing material due to the difference of work function, which effectively adjusted the oxygen vacancy concentration, improved the electrocatalytic activity of the material, and reduced the working temperature. The response showed a piecewise linear correlation with the concentration of H 2 S, and its sensitivity for 0.2–2 ppm and 2–10 ppm H 2 S was −6.4 and −36.35 mV/decade, respectively. Furthermore, the sensor exhibited good stability, repeatability, and selectivity to H 2 S. This study showed that the GDC-based mixed potential sensor with Co 3 O 4 /ZnO/Y 2 O 3 -SE could be used as a potential sensor for detecting low concentration of H 2 S. [ABSTRACT FROM AUTHOR]

Triethylamine is a vital chemical raw material, but its leakage will pollute the environment and harm human health. It is particularly important to achieve detection of triethylamine. Here, PdRu nanoparticles, ZnO long-grained nanoparticles and C 3 N 4 were prepared for the identification of low concentrations of triethylamine. The response value of the sensor based on PdO-Ru/ZnO-C 3 N 4 1 to 20 ppm triethylamine was 96 at 220 °C. Furthermore, the lowest detection amount of it was as low as 50 ppb. And the time for rapid detection of 20 ppm triethylamine was shown to be 1 s. Besides, a circuit was designed to detect triethylamine in real time and raise the alarm when the concentration of triethylamine exceeded a threshold. The catalytic ability of PdRu nanoparticles and the formation of n-n heterojunction between ZnO and C 3 N 4 were conducive to enhancing the sensing performance. This work provides a way for monitoring of triethylamine and timely warning in chemical plants. [Display omitted] • PdO-Ru/ZnO-C 3 N 4 1 showed a high response (R a /R g = 96) to 20 ppm triethylamine at 220 °C. • The sensor had a short response time of 1 s • The lowest detection amount of PdO-Ru/ZnO-C 3 N 4 1 was as low as 50 ppb. • A circuit was designed to detect triethylamine in real time and could raise the alarm. [ABSTRACT FROM AUTHOR]

A high-performance low-humidity sensor and moisture-enabled electric generator are prepared through a mesoporous silica-mediated polymerizable deep eutectic solvent platform. The strong hydrophilicity and high ionic conductivity of ionogels are the main reasons for realizing dual-function devices. This work provides a novel approach for the combination of humidity detection and utilization. [Display omitted] • Mesoporous silica/polymerizable deep eutectic solvent functionalized ionogels were prepared by UV light stimulation. • Mesoporous silica containing abundant hydroxyl groups can regulate the intermolecular forces in polymer networks. • Low-humidity sensing and moisture-enabled electric generation can be realized simultaneously through functionalized ionogels. Although technologies related to humidity detection and utilization, such as humidity sensors, atmospheric water harvesting, energy collection, and moisture-enabled electrical generation technologies, have been widely reported, there is still an urgent need for effective monitoring and utilization of humidity in low-humidity places. An ideal low-humidity sensor requires a high response, fast response time and low humidity hysteresis. Soft ion power supplies inspired by electric eels convert the chemical potential energy of ion gradients into electrical energy by utilizing humidity, but their production is challenging. This paper reports a new strategy for developing functionalized ionogels based on mesoporous silica and a polymerizable deep eutectic solvent (SiO 2 @PDES). Due to their strong hydrophilicity, high ionic conductivity, excellent adhesion, flexibility and mechanical strength, SiO 2 @PDES ionogels can not only detect low humidity but also generate electric power through a reasonably designed device structure. In the 5–30% RH range, the response of the SiO 2 @PDES humidity sensor reaches 1600%, with negligible humidity hysteresis (0.8% RH). As a biomimetic soft ion power supply, SiO 2 @PDES ionogels generate a high open-circuit voltage of ∼600 mV at 33% RH, which expands the environmental adaptability of moisture-enabled electrical generation equipment. In addition, the excellent moisture-enabled electrical generation performance endows portable wearable power supplies with high potential for applications such as charging capacitors and lighting LEDs. [ABSTRACT FROM AUTHOR]

Mesoporous metal oxides have been reported as promising semiconductor gas sensing materials, showing great potential in detecting volatile organic compound (VOC) pollutants in the air. Here, we present the use of mesoporous Ru doped SnO 2 oxide semiconductor, derived from a bimetallic organic framework (MOF), as a composite material for high-performance TEA gas sensing. Mesoporous structure of bimetallic MOF-derived composites synthesised using a one-step method, has a high porosity and large specific surface area (69.48 m2 g−1), which can enhance the number of sensing reaction sites and improve its capturing ability for the target gas. Moreover, the in-situ substitution of Ru3+ ions for Sn4+ ions can adjust the carrier concentration. Therefore, the synthesized mesoporous 0.4 mol% Ru-SnMOF@SnO 2 exhibits high sensitivity, excellent selectivity, fast response kinetics, and good long-term stability for TEA sensing at 250 °C. Exceptionally, there is still an impressive response (S = 125.5–100 ppm) to triethylamine at 80 % RH. The relative humidity was set at 25 °C. [Display omitted] • 0.4 mol% Ru-SnMOF@ SnO 2 at 250 °C, still showed high response to 100 ppm triethylamine at 80 % RH (R a /R g = 125.5). [ABSTRACT FROM AUTHOR]

A series of different facile modification layers (MLs) was designed to gradually increase the electrochemical sensing performance of glassy carbon electrode (GCE) for simultaneously detecting Pb2+ and Cu2+. ML designs were mainly a different combination of ZIF-67, MWCNT and Nafion, and their different electrochemical sensing performances were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), square wave stripping voltammetry (SWSV) and chronocoulometry. The fabricated sensor, which modified with ZIF-67/MWCNT and Nafion layer, exhibited the biggest response peak current to Pb2+ and Cu2+. In addition, it displayed a wide linear detection range of 1.38 nM–5 μM for Pb2+ and 1.26 nM–5 μM for Cu2+, a detection accuracy of about 1 nM for both Pb2+ and Cu2+, and an excellent stability for both Pb2+ and Cu2+. We also analyzed the real water sample taken from Changchun's Sanjia Lake and Yan Lake. We believe this ML design provides instruction for building high-performance electrochemical sensing systems. Image 1 • A novel multiphase modification layer based on ZIF-67/MWCNT/Nafion was constructed. • This modification layer greatly improved Pb2+ and Cu2+ sensing performance. • The sensor displayed a low detection limit of 1.38 nM for Pb2+ and 1.26 nM for Cu2+. [ABSTRACT FROM AUTHOR]

Triethylamine (TEA) is a significant compound, but it is toxic and flammable. Since the humidity in the environment is constantly changing, it is meaningful to develop a sensor that can detect TEA efficiently and is less disturbed by humidity. Here, Pd nanoparticles with a small particle size (about 4 nm) were prepared by reduction method and dispersed on Co-MOF (ZIF-67). Pd@ZIF-67-derived trace PdO and Co 3 O 4 nanoparticles were evenly decorated on SnO 2 nanofibers by electrospinning and calcination. The ratios of PdO to SnO 2 in PdO-Co 3 O 4 -SnO 2 were 0.012 wt% and 0.048 wt%, respectively. The response of the sensor based on 0.012 wt% PdO-Co 3 O 4 -SnO 2 to 20 ppm TEA was 14 at 240 °C. The response time was 3 s and the lowest concentration actually detected was 1 ppm. The synergistic effects of oxygen vacancy, p-n junction, electron sensitization of PdO and morphology of composite improved sensing performance. In addition, due to the inhibition of hydroxyl poisoning by PdO and the oxidation assisting effect of Co 3 O 4 , the composite had excellent humidity resistance. [Display omitted] • Pd nanoparticles with a small particle size (about 4 nm) were dispersed on Co-MOF (ZIF-67). • Trace PdO (0.012 wt%) and Co 3 O 4 nanoparticles were evenly decorated on SnO 2 nanofibers. • The composite had excellent humidity resistance. • The sensor had a short response time of 3 s. [ABSTRACT FROM AUTHOR]

Trace detection and early warning of H 2 leakage at high temperatures are of great significance in eliminating potential safety risks and ensuring the safety of human life and property. Herein, Ce 0.8 Gd 0.2 O 1.95 -based mixed potential high temperature H 2 sensors made of AgRu@WO 3 synthesized by photochemical reduction method as the sensing materials are designed and demonstrated. By adjusting the content of Ag in WO 3 and the ratio of Ag and Ru, the sensitivity of the sensor is effectively improved and the operating temperature is reduced. The interaction between Ag and WO 3 (synergistic hydrogen spillover effect) is the major reason for the sensitivity of sensors to H 2. Ru is further introduced with the aim of using its catalytic and dissociative capabilities to make the optimal operating temperature of the sensor well below the deflagration point of H 2 (520 °C for Ag@WO 3 to 430 °C for AgRu@WO 3). At 430 °C, H 2 in the range of 2–2000 ppm can be detected by such sensors. The response value to 50 ppm H 2 can reach − 79 mV. Analysis using X-Ray Diffractometer (XRD), Scanning Electron Microscope (SEM) and X-ray Photoelectron Spectroscopy (XPS) are performed to explore the formations of AgRu@WO 3 and its sensing mechanism. To the best of our knowledge, there are no reports on the use of bimetallic-modified metal oxide sensing materials for Ce 0.8 Gd 0.2 O 1.95 solid electrolyte sensors in order to simultaneously increase the sensitivity and reduce the operating temperature. This study provides a new reference for subsequent researchers in the selection of sensing materials for solid electrolyte sensors, as well as a new option for accurate and stable detection of H 2 at high temperatures. • Ce 0.8 Gd 0.2 O 1.95 -based mixed potential sensor is designed for H 2 detection under high temperature. • Response to 50 ppm H 2 is increased to -79 mV which is attributed to the hydrogen spillover effect between Ag and WO 3. • Operating temperature is reduced from 520°C to 430°C which is attributed to the catalytic and dissociation ability of Ru. • The sensor shows wide detection range (2-2000 ppm), good selectivity and resistance to humidity. • The sensor provides a new option for accurate and stable detection of H 2 at high temperatures. [ABSTRACT FROM AUTHOR]

In this work, nitrogen doped carbon fiber loaded copper (Cu/CF-N) sensing electrode and Nafion proton conductor are used to fabricate fuel cell type gas sensors that realize fast response/recovery for SO 2 detection at room temperature. This is the first time that this type of sensor has been used to detect SO 2. We investigated the effect of Cu content on sensors' performance, and found that the Cu (20 wt%)/CF based sensor exhibited the highest response. This can be attributed to the optimal Cu content, which exposes the most active sites. Moreover, nitrogen was doped into electrode material to further improve the performance. Nitrogen atoms enhance the conductivity of the material and its ability to adsorb SO 2. These are confirmed by the complex impedance measurement and TPD analysis. The upgraded Cu/CF-N fuel cell type gas sensor showed a response of − 435.6 nA to 50 ppm SO 2 and a low detection limit of 500 ppb. Significantly, the Cu/CF-N sensor demonstrated short response time (44 s) and recovery time (87 s) at room temperature. Furthermore, with the advantages of no power consumption, excellent selectivity and good repeatability, the fuel cell type gas sensors have broad prospects in the field of room temperature gas detection. ● The fuel cell type gas sensor realizes the detection of SO 2 for the first time. ● This work provides guideline to extend the applications of fuel cell type gas sensor. ● The Cu/CF-N sensor shows short response/recovery time of 44 s/87 s at room temperature. ● The device can detect SO 2 from 0.5 to 50 ppm. [ABSTRACT FROM AUTHOR]

Expanding the application field of fuel cell type gas sensors is of great significance for achieving high sensitivity, real-time gas detection at room temperature. Here, we developed a fuel cell type NO 2 gas sensor based on MoS 2 nanosheet/Carbon fiber (CF) sensing electrode and Nafion proton conductor, enabling the fuel cell type sensor to detect NO 2 for the first time. The effect of MoS 2 loadings(10, 20, 40, 60 and 80 mg) on the sensors' performance and the sensitizing mechanism are investigated, the sensor containing 40 mg MoS 2 exhibits the best performance, which can be attributed to the large number of active sites and efficient carrier transport properties of the corresponding electrode materials. At room temperature, the optimal sensor demonstrates a sensitivity of 45.6 nA/ppm to 1–50 ppm NO 2 and an ultra-low detection limit of 28.8 ppb, both the response and recovery time are less than 60 s. This work not only develops a highly sensitive, reversible and fast response NO 2 gas sensor, but also provides insights into sensing electrochemistry, material selection and catalyst/support materials, offering guidelines for future fuel cell type gas sensors to monitor a wider range of environmental pollutants. • The fuel cell type gas sensor realizes the detection of NO 2 for the first time. • The insights on sensing materials provide guidelines to extend the detection range of fuel cell type gas sensors. • The MoS 2 /CF fuel cell type sensor shows short response/recovery time of 55 s and 55 s at room temperature. [ABSTRACT FROM AUTHOR]

• Sensing electrode materials MMnO3 (M: Gd, Sm, La) were first developed to fabricate NASICON-based triethylamine sensors. • The sensor utilizing SmMnO3-SE displayed an ultralow detection limit of 50 ppb with the response value (-5.6 mV). • The sensitivity of the sensor is -49 mV/ppm and -105 mV/decade at the ranges of 0.05-1 ppm and 1-50 ppm TEA, respectively. • The sensor displayed good reliability, stability and selectivity. In this work, the mixed-potential-type gas sensor based on NASICON solid electrolyte and MMnO 3 (M: Gd, Sm, La) sensing electrode (SE) was developed and fabricated aiming at the low-concentration triethylamine (TEA) detection. The research point of the fabricated sensors mainly concentrated on the effect of different A-site elements in MMnO 3 -SE (M: Gd, Sm, La) on TEA sensing characteristics. The result reveals that the highest response value (−217.5 mV) towards 50 ppm TEA was observed for the device utilizing SmMnO 3 -SE. The highest electrochemical catalytic activity of the fabricated sensors attached with SmMnO 3 -SE was further authenticated by the polarization curve measurement. Moreover, the response value displays a segmentally linear relationship with TEA concentrations and the logarithm of TEA concentrations, and the slopes are −49 mV/ppm and −105 mV/decade at the ranges of 0.05–0.5 ppm and 1–50 ppm TEA, respectively. The device could also produce an acceptable response value (−5.6 mV) towards 50 ppb TEA. Moreover, it also displays good repeatability and selectivity, along with steady response signals towards 5 ppm and 50 ppm TEA for 15 days and 1 ppm TEA at different humidity levels. [ABSTRACT FROM AUTHOR]

• A porous SnO 2 /Zn 2 SnO 4 sensing electrode was firstly fabricated the YSZ-based mixed-potential type C 2 H 2 gas sensor. • The SnO 2 /Zn 2 SnO 4 -SE sensor showed the response value of -82.3 mV toward 100 ppm C 2 H 2 and low detection limit of 500 ppb. • The response and recovery times of the sensor using porous SnO 2 /Zn 2 SnO 4 -SE to 100 ppm C 2 H 2 were 7 s and 15 s at 700 °C. • The sensor showed good sensitivity and reproducibility to C 2 H 2 after 20 days consecutive measurement of 700 °C. Here, the porous SnO 2 /Zn 2 SnO 4 sensing electrode material prepared by facile hydrothermal method was applied to fabricate the mixed-potential-type gas sensor based on yttrium-stabilized zirconia (8 mol% Y 2 O 3 -doped ZrO 2) solid electrolyte plane substrate for effectively detecting acetylene (C 2 H 2) at 700 °C. In terms of the sensing characteristics of the C 2 H 2 gas sensor, the response value toward 100 ppm C 2 H 2 was -82.3 mV, and the detection limit of C 2 H 2 was lowered to 500 ppb. The ΔV of the sensing device varied piecewise linearly with the logarithm of C 2 H 2 concentration gradient range of 0.5–2 and 5–1000 ppm, with sensitivities of -12 and −56 mV/decade, respectively. In addition, the sensor exhibited good humidity stability, long stability, and selectivity to C 2 H 2 at 700 °C. More interestingly, after high-temperature measurement (700 °C) for 20 consecutive days, the sensor continued to present good response transients, sensitivity, and reproducibility to C 2 H 2. Furthermore, the sensing mechanism of the mixed-potential-type sensor was verified by measuring the polarization curves and complex impedance curves. [ABSTRACT FROM AUTHOR]

• The superfine porous NiFe2O4 microspheres were successfully synthesized via a one-step solvothermal approach. • The porous NiFe2O4 sensors exhibited high and rapid response for selective detection of acetone gas. • The porous NiFe2O4 sensors exhibited low detection limit (200 ppb) to acetone gas. Spinel-type oxides have attracted a broad interest in sensing materials research owing to their high catalytic activity and flexibly tunable chemical properties. Here, we report the synthesis of superfine porous NiFe 2 O 4 microspheres by one-step solvothermal approach, in order to fabricate ultra-sensitive acetone sensors for real-time monitoring, relying on the high catalytic activity of NiFe 2 O 4 and effective mass transfer property of porous microspheres structure. The porous NiFe 2 O 4 sensors displayed high selectivity to acetone against other interfering gases, giving a high sensitivity (27.4), fast response time (2 s) towards 100 ppm acetone and low detection limit (200 ppb) at 250 °C. This paper proposed a general approach for fabricating highly sensitive gas sensor based on spinel-type oxides in monitoring volatile organic pollutants. [ABSTRACT FROM AUTHOR]

Highlights • Room temperature NH3 sensor based on WO3 hollow spheres@ polyaniline assembled on flexible PET substrate was developed. • The sensor utilizing PAWHs 10 hybrid showed the highest response of 25- 100 ppm NH3 at room temperature. • The sensor has ppb- level detection limit of 1.67- 500 ppb NH3 indicated the potential use on the trace NH3 detection. • The improved sensing performance was attributed to the hollow structure and the formation of p-n heterojunction. Abstract The development of room temperature NH 3 sensors with flexible substrate can fulfill the future demands of high NH 3 sensing performance under the premise of lower energy consumption and safety circumstance in wearable electronics field. The polyaniline and a serious of WO 3 hollow spheres@ polyaniline hybrid were successfully synthesized via a combined route of simple hydrothermal method and in-situ chemical oxidative polymerization. The room temperature NH 3 sensors were fabricated by assembling WO 3 hollow spheres@ polyaniline hybrid on flexible polyethylene terephthalate (PET) films. The NH 3 sensing properties of the fabricated devices demonstrated that the device utilizing 10 mol% WO 3 hollow spheres@ polyaniline (PAWHs 10) hybrid exhibited the best sensing performance to 100 ppm NH 3 (response value at 25) at 20 °C. Moreover, the PAWHs10 hybrid sensor also achieved excellent NH 3 selectivity, ppb-level detection limit (1.67–500 ppb NH 3), and good response/recovery rates (136 s/130 s) at 20 °C. The enhanced sensing performance of incorporation of polyaniline and WO 3 hollow spheres was mainly attributed to the hollow structure of WO 3 and the formation of p-n heterojunction between PANI and WO 3 hollow spheres. [ABSTRACT FROM AUTHOR]

Highlights • The SnO 2 /Zn 2 SnO 4 porous spheres were synthesized via a facile one-step hydrothermal method. • The porous SnO 2 /Zn 2 SnO 4 spheres exhibited excellent ethanol gas sensing property. • The porous SnO 2 /Zn 2 SnO 4 spheres possess a low detection limit of 500 ppb. • The sensor based on porous SnO 2 /Zn 2 SnO 4 spheres exhibited a rapid response time of 2 s. Abstract In this work, hierarchucal porous SnO 2 /Zn 2 SnO 4 nanospheres were succesfully prepared via a facile one-step hydrothermal method with subsequent calcination process. Scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were employed in order to investigate the structural and morphological properties of the as-prepared composites. The results showed that the SnO 2 /Zn 2 SnO 4 composites were cpmposed of many porous nanospheres with a uniform diameter of about 500 nm. Moreover, the as-prepared products were used as sensing material for the fabrication of gas sensor. The sensing performance of the sensor was systematically evaluated, and the sensor exhibited excellent ethanol-sensing property. The optimum operating temperature was 250 °C with a reponse of 30.5 toward 100 ppm ethanol. Also, the sensor showed good selectivity, stability and a low detection limit of 0.5 ppm (response 1.4). The good sensing performance of SnO 2 /Zn 2 SnO 4 nanospheres can be attibuted to the porous structure as well as the heterojunction formed between SnO 2 and ZnSn 2 O 4. [ABSTRACT FROM AUTHOR]

Highlights • One step synthesis of branched SnO 2 /ZnO heterostructures and their enhanced gas-sensing properties. • Branched SnO 2 /ZnO heterostructures were synthesized via a facile one-step hydrothermal method for the first time. • The branched SnO 2 /ZnO heterostructures exhibited excellent ethanol gas sensing property. • The branched SnO 2 /ZnO heterostructures exhibited fast response and recovery property for selective detection of ethanol. Abstract In this work, a novel branched heterostructural composite composed of nanorods ZnO backbone and SnO 2 branches was prepared via a facile one-step hydrothermal method. The morphology, structure and component of the SnO 2 /ZnO composite was characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and elemental mapping analysis. The evolution process of the SnO 2 /ZnO composite was observed by SEM that the SnO 2 branches gradually grow on ZnO backbones. The composite with novel heterostructure was applied as the sensing material for the fabrication of gas sensor, and their gas sensing properties were tested for response to various gases. Compared to pure ZnO gas sensors the branched SnO 2 /ZnO gas sensor exhibited enhanced gas sensing properties toward ethanol, giving a response of 18.1–100 ppm. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Hedgehog-like titanium dioxide (TiO 2) architectures composed of hundreds of one-dimensional (1D) nanorods and silver (Ag) loaded TiO 2 with different amounts (0.2 at%, 0.5 at% and 1 at%) were successfully prepared by facile hydrothermal process and simple isometric impregnation route. The high electron mobility of 1D nanorods on the surface of TiO 2 and the high porosity of Ag loaded hedgehog-like TiO 2 architectures enable the sensor with fast responsive and recovered properties. TiO 2 loaded with 0.5 at% Ag exhibited the highest response to xylene with low response/recovery time at the operating temperature of 375 °C. In addition, the sensitivity and selectivity of the TiO 2 sensor were enhanced markedly with Ag loading. [ABSTRACT FROM AUTHOR]

Abstract Urchin-like hierarchical Zn doped CdS powders were successfully synthesized via simple one-pot hydrothermal process. Their SEM and TEM images indicated that the hierarchical structure were assembled by single crystal nanorods with the hexagonal wurtzite phase. EDS element mapping verified that Zn ions were homogeneously distributed among the hierarchical microstructure. The performances of gas sensors based on pure and Zn doped CdS were measured and compared. The results indicated that Zn doping could enhance their responses to some volatile organic compounds and improve its selectivity to ethanol and toluene as well. The possible reasons for this enhancement were investigated. In addition, the sensor based on Zn doped CdS exhibited the ultrafast response and recovery to ethanol ( τ response < 1 , τ recovery = 8 s), indicating that the Zn doped CdS could be a promising gas sensing candidate for online monitoring of ethanol. Graphical abstract Image 1 Highlights • Hierarchical urchin-shaped Zn doped CdS was prepared via hydrothermal route. • The Zn element played a crucial role in enhanced gas sensing of CdS. • The Zn doped CdS microspheres exhibited excellent sensitivity. [ABSTRACT FROM AUTHOR]

Highlights • The highly selective and stable mixed potential type YSZ-based gas sensor using Cd 2 V 2 O 7 -SE was fabricated for effective detection of NH 3 at 650 °C. • The sensor attached with Cd 2 V 2 O 7 -SE displayed the response value of −68 mV and rapid response rate of 5 s to 100 ppm NH 3 at 650 °C. • The fabricated device showed good repeatability, excellent selectivity, humidity resistance and long-term stability. • The sensitivities of the sensor decreased by 1 mV/decade to 1–10 ppm NH 3 and 2.5 mV/decade to 10–200 ppm NH 3 after 30 days measurement of 650 °C. Abstract In this work, the highly selective and stable mixed potential type stabilized zirconia (YSZ) based gas sensor using Cd 2 V 2 O 7 sensing electrode (SE) synthesized via simple coprecipitation method was fabricated and developed for effective detection of NH 3 at 650 °C. The as-prepared Cd 2 V 2 O 7 sensing material was characterized by X-ray diffraction (XRD), Raman spectrum, X-ray photoelectron spectroscopy (XPS) and Field-emission scanning electron microscopy (FESEM). The results of gas sensing measurement indicated that the sensor attached with Cd 2 V 2 O 7 - SE displayed the response value of −68 mV and rapid response rate of 5 s to 100 ppm NH 3 at 650 °C. The present device also exhibited the low detection limit of 1 ppm and the piecewise sensitivities of −6 and −66 mV/decade to NH 3 in the concentration ranges of 1–10 ppm and 10–200 ppm, respectively. Moreover, the fabricated sensor showed good reproducibility, excellent selectivity, stability to oxygen concentration, relative humidity and 30 days continuous aging of high temperature at 650 °C. And the complex impedance and polarization curves were performed to explain the selectivity and verify the sensing mechanism involving mixed potential model. [ABSTRACT FROM AUTHOR]

Highlights • A series of K 2 NiF 4 -type oxides Sm 2-x Sr x NiO4 (x=0.4, 0.6 and 0.8) were first developed to fabricate acetone sniffer. • The device utilizing Sm 1.4 Sr 0.6 NiO 4 -SE performed the largest response of −20 mV to 5 ppm acetone. • The lowest detection limit of the sensor based on Sm 1.4 Sr 0.6 NiO 4 -SE to acetone was 300 ppb. • The sensor displayed prominent reliability, humidity resistance and stability. • The sensor performed a manifest and stable signal during all of tests to the exhaled breathes of the diabetics. Abstract Acetone sniffer, because of its ability of continuous non-invasive monitoring, is recognized as a potential method for the diagnosis of diabetes. In this study, mixed potential electrochemical sensors based on YSZ and K 2 NiF 4 -type oxides Sm 2-x Sr x NiO 4 (x = 0.4, 0.6 and 0.8) sensing electrode were fabricated as bio-sniffer for diagnosis of diabetics by detecting acetone concentration in exhaled breath. The results showed that when Sm 1.4 Sr 0.6 NiO 4 was used as sensing material, the fabricated sensor exhibited the best performance in comparison with other sensors, the present device also exhibited prominent reliability, excellent humidity resistance and good stability over 30 days. What's more, the low detection limit of sensor to acetone was 300 ppb, indicating that the sensor had ability for acetone detection in exhaled breath. The exhaled breathes of the diabetics with ketosis were used for detection and results showed that the sensor had a manifest and stable signal. Besides, the response and recovery time were also acceptable to real-time detection. In addition, the relationship of the blood ketone level and the acetone concentration in exhaled breath was given in the paper. Above all, the fabricated sensor has enormous potentiality for the diabetes monitoring through breath analysis. [ABSTRACT FROM AUTHOR]

Detection and prevention of some hazardous gas pollutants has always been a challenging problem. SO 2 , as a typical toxic and dangerous gas, is extremely difficult to be monitored stably because of its toxicity to gas detecting equipment. In this work, we report a high-performance YSZ-based mixed potential sensor to realize continuously on-line detection of SO 2. In view of shortcomings of high temperature SO 2 sensors such as poor stability, slow response and recovery rate and easy deterioration, Pd/Al 2 O 3 catalyst was mixed thoroughly with Mn/Ce composite oxide and sintered to construct sensing electrode and an improved scheme combining high-temperature pulse and catalyst was proposed to decompose sulfate deposit and improve recovery characteristics. EDS and XPS measurements were used to verify the reason for improvement of SO 2 sensing performance. Through the strategy proposed in this study, recovery time of the high temperature SO 2 sensor to 5 ppm SO 2 was reduced from 665 s to 73 s, indicating its fast-detecting ability. The detection range is 0−20 ppm (resolution ratio:1 ppm), meeting SO 2 detection requirement. Moreover, stability of SO 2 sensor during 10 days was significantly enhanced. This SO 2 sensor is suitable for application in hazardous gas detection field due to its miniaturized, cost-effective, satisfying stability and selectivity, and fast response and recovery features. • Fast and complete recovery was achieved on YSZ-based mixed potential SO 2 sensor. • Sulfate produced hindered sensor's full recovery and degraded its stability. • High-temperature pulse and Pd catalyst in SE co-promoted sulfate's decomposition. • The sensor showed a considerate sensitivity of −34.7 mV/decade to 1−20 ppm SO 2. • The sensor is suitable for SO 2 detection in 500–625 °C and 25–60 % RH condition. [ABSTRACT FROM AUTHOR]

Highlights • Mixed potential type acetone sensors based on MFeO 3 (M: Bi, La and Sm)-SE and CeO 2 have been first developed. • The response of the sensor utilizing BiFeO 3 (sintered at 800 °C)-SE to 100 ppm acetone was −99 mV. • The sensitivity of the sensor to 5–200 ppm acetone were −75 mV/decade. • The sensor also displayed excellent long-term stability after 40 days continuous measurement at 600 °C. Abstract In order to obtain high-performance CeO 2 -based mixed potential type acetone sensors, MFeO 3 (M: Bi, La and Sm) sensing electrode materials were prepared by sol-gel method. The present study mainly focused on the effect of sensing electrode material and sintering temperature on sensing performance of sensors. The results showed that the sensor used BiFeO 3 -SE sintered at 800 °C presented the best sensing characteristic to acetone at 600 °C, which can detect even 1 ppm acetone with an acceptable response value. The response value (ΔV) of the sensor changed proportionally with the logarithm of acetone concentration at the ranges of 1–5 ppm and 5–200 ppm, and the slopes of which were −7 and −75 mV/decade, respectively. The sensor also showed excellent repeatability, relatively good selectivity, resistance to humidity and good long-term stability. The high-sensing characteristics of the sensor attached with BiFeO 3 -SE sintered at 800 °C to acetone were explained in terms of morphology and electrocatalytic activity of sensing electrode, which are validated by SEM, BET, XPS, polarization curves and complex impedance. [ABSTRACT FROM AUTHOR]

Highlights • La-doped In 2 O 3 hollow microspheres preparing via one-step hydrothermal route. • Excellent sensitivity of H 2 S basing on 3.0 mol% La-doped In 2 O 3. • Analysis of enhanced gas sensing properties causing by La doping. Abstract The undoped and 1.0–5.0 mol% La–doped In 2 O 3 hollow microspheres have been successfully synthesized via a simple hydrothermal method without template and gas sensor have been fabricated basing on them. The nanostructures and morphologies of the maintained hollow spheres were characterized by various experimental techniques. The gas sensing properties of these hollow microspheres were investigated systematically. The results indicated that among all the samples (pure, 1.0, 3.0 and 5.0 mol% La–doped In 2 O 3), 3.0 mol% La–doped In 2 O 3 exhibited the highest response toward 10 ppm hydrogen sulfide (H 2 S) at 200 °C, having a response value of 17.8, approximately 4.8 times higher than pure In 2 O 3. Furthermore, excellent selectivity, good repeatability and outstanding long-term stability were also achieved. The significantly enhanced sensing properties to H 2 S could be attributed to the changes in distribution of different oxygen components, crystallite size and specific surface area caused by La doping. [ABSTRACT FROM AUTHOR]

Mulberry-shaped tin oxide (SnO 2 ) hierarchical architectures and samarium oxide (Sm 2 O 3 ) loaded tin oxide with different amounts (0.5, 1, 2.5, and 4 mol% Sm 2 O 3 ) were successfully synthesized by facile hydrothermal synthesis method and simple isometric impregnation method. The gas sensing performance of the sensors based on pure SnO 2 and Sm 2 O 3 loaded SnO 2 materials were systematically investigated. The results indicated that Sm 2 O 3 loading considerably affected the improvement of the sensing performance of the SnO 2 sensor. The 2.5 mol% Sm 2 O 3 /SnO 2 exhibited the highest response (41.14) to 100 ppm acetone, the response was 2.29 times higher than that of pure SnO 2 (18). In addition, with 2.5 mol% Sm 2 O 3 loading, the low detection threshold of the sensor dropped from 500 ppb to 100 ppb. The enhanced gas sensing performance was mainly bacause of the increased oxygen vacancies created by the substitution of samarium in the SnO 2 lattice, which enhanced the adsorption of oxygen and the exceptional catalytic effect of Sm 2 O 3 . [ABSTRACT FROM AUTHOR]

In this paper, an amperometric gas sensor based on proton exchange membrane (Nafion) was fabricated for H 2 S detection at room temperature. Pt-Rh nanoparticles loaded on carbon fibers, as sensing electrode, was prepared by chemical reduction method, and membrane electrode assemble (MEA) was fabricated using hot-pressing method. X-ray diffractometry (XRD) and field emission scanning electron microscopy (FESEM) were used to analyze the structure and morphology of the fabricated electrode material. The effect of the weight ratio of Pt to Rh on the performance of the sensor was investigated and the results showed that the sensing performance was best when the ratio of Pt to Rh was 1:1. Moreover, the sensitivity had been significantly improved due to the use of carbon fibers pretreated by nitric acid, increasing from 0.158 μA/ppm to 0.191 μA/ppm. The present sensor could detect H 2 S at levels as low as 0.1 ppm with a −20 nA response and had a good linear relationship in the range of 0.1 to 200 ppm H 2 S. In addition, this amperometric H 2 S sensor displayed fast response-recovery rate as well as excellent selectivity and stability. [ABSTRACT FROM AUTHOR]

Flower-liked ZnO architectures and Ce doped ZnO materials with different amounts (0.2, 0.5, 1.2 and 2 at% Ce) were successfully synthesized by a simple room-temperature precipitation route. As the gas sensing materials, their sensing performance were investigated systematically. The results indicate that Ce doping can improve the performance of ZnO sensor. The ZnO doped with 0.5 at% Ce exhibited the highest response to ethanol at the operating temperature of 300 °C, and the response value was about 72.6–100 ppm ethanol. With Ce doping, the proportions of oxygen vacancy and chemisorbed oxygen species were increased obviously, which could greatly promote the gas sensing properties of surface resistance-type metal oxide semiconductors. Thus, the doping of flower-liked ZnO with Ce should be a promising approach for designing and fabricating the high performance gas sensor. [ABSTRACT FROM AUTHOR]

Ultra-small Pt nanoparticles functionalized In 2 O 3 nanofibers have been designed by using a new catalyst loading platform (Pt@ZIF-8), which involves three steps including the synthesis of ZIF-8 nanoparticles, the preparation of Pt@ZIF-8 and the subsequent transformation to Pt-ZnO-In 2 O 3 composite nanofibers by electrospinning. The experimental results demonstrate that the average sizes of Pt nanoparticles obtained in this way are only ∼3 nm, which is helpful to obtain highly sensitive gas sensors due to the ultra-small Pt nanoparticles. Gas sensing investigations indicate that the sensor based on Pt-ZnO-In 2 O 3 nanofibers exhibit the superior acetone response (R a /R g  = 57.1 to 100 ppm at 300 °C), ultra-fast response and recovery time (1/44s) and low detection limit (0.5 ppm). In this study, the excellent acetone gas sensing property of Pt-ZnO-In 2 O 3 nanofibers attributes to the chemical sensitization and electrical sensitization of the ultra-small Pt nanoparticles, the n-n heterojunctions between ZnO and In 2 O 3 , and the p - n heterojunction produced between p-type PtO 2 and n-type In 2 O 3 (ZnO). [ABSTRACT FROM AUTHOR]

An ultrafast-response yttria stabilized zirconia (YSZ)-based mixed potential type gas sensor utilizing molybdate CoMoO 4 sensing electrode was developed to realize the effective detection of triethylamine (TEA) at 600 °C. The gas sensing characteristic of the fabricated sensor was optimized by changing the calcination temperature of CoMoO 4 sensing material and results indicated that the device attached with CoMoO 4 -SE sintered at 1000 °C exhibited the highest response value (−102 mV) to 100 ppm TEA and low detection limit of 100 ppb at 600 °C. Interestingly, the response and recovery times of the present sensor to 100 ppm TEA were 1 s and 10 s, which signified the ultra-fast response rate. The response value of fabricated sensor displayed the piecewise linear function to logarithm of TEA concentrations and the sensitivities were −14 mV/decade (0.1–5 ppm) and −53 mV/decade (5–200 ppm), respectively. More importantly, the present sensor also exhibited good repeatability, selectivity, slight effect of humidity and long-term stability of 20 days, indicating a great candidate for use in detection of TEA. Furthermore, the device based on mixed potential mechanism was proposed and further verified using polarization curve. [ABSTRACT FROM AUTHOR]

Carbonization followed by calcination in air has been developed to synthesize porous SnO 2 based nanofibers. The precursor nanofibers were synthesized through electrospinning. The optimal synthesized condition was investigated according to the gas sensing properties of pure SnO 2 nanofibers through adjusting the heating rate in air. Gas sensors based on 1% Pd doped SnO 2 nanofibers under this optimal synthesized condition were fabricated, and the gas sensing properties was systematically investigated. The experimental results indicate that all the carbonized nanofibers have a porous microstructure. For the pure SnO 2 nanofibers, carbonized nanofibers also have a hollow structure. At the optimal synthesized condition, the sensor based on the carbonized SnO 2 nanofibers Exhibits 2.6 times higher response (20.4) than pristine pure SnO 2 nanofibers (7.7) toward 100 ppm ethanol. However, the selectivity is almost unchanged. For the Pd doped SnO 2 nanofibers, the gas response is improved from 10 to 24.6 to 100 ppm toluene at optimum operation temperature under the carbonization process. The sensors also exhibit a low detecting limit (1.6–500 ppb toluene) and a short response time (∼3 s). The evolution process and the formation mechanism were also discussed. [ABSTRACT FROM AUTHOR]

Yolk-shell nanomaterials with controlled morphology have received great attention because of their promising applications in gas sensing. Here, we reported the facile synthesis of pure and 1–5 mol% Sn doped Co 3 O 4 yolk-shell nanostructures by calcinating the Co based metal–organic framework (MOF, ZIF-67) prepared from hydrothermal method. The morphologies of the as-obtained samples were characterized by various experimental techniques. Furthermore, the gas sensing properties were systematically measured. Gas sensors based on 3 mol% Sn doped Co 3 O 4 yolk-shell nanostructures exhibited extremely enhanced response to ethanol at 200 °C (R g /R a  = 13.4–100 ppm at 200 °C) and low detection limit (R g /R a  = 1.3–1 ppm ethanol at 200 °C). Most importantly, the gas response to 100 ppm ethanol is still maintained well after continuous measurement for 20 days. [ABSTRACT FROM AUTHOR]

Porous CuFe 2 O 4 nanospheres were successfully prepared via a facile solvothermal method with subsequent calcination treatment. Various techniques were employed to investigate the structural and morphological characteristics of the as-synthesized product. The results revealed that the hierarchical CuFe 2 O 4 porous nanospheres with a diameter of about 200 nm were composed of many nanoparticles. In addition, gas sensors were fabricated with the as-prepared samples, and their gas sensing performances were systematically investigated. Compared with pure CuO and Fe 2 O 3 nanoparticles, the CuFe 2 O 4 nanostructure exhibited superior gas sensing properties toward acetone at the operating temperature of 250 °C, including high response, outstanding selectivity, and excellent response-recovery property. [ABSTRACT FROM AUTHOR]

Hierarchical NiO nanomaterials doped by 0.5, 1.0, 1.5 and 2.0 at% Sn 2+ ions were synthesized through a facial hydrothermal route. The isovalent Sn 2+ ions were selected as dopants and occupied the interstitial spaces of NiO lattice. Such obtained NiO specimens were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) etc. and used as sensing materials for gas sensors. The comparative sensing property tests among these Sn 2+ doped NiO sensors demonstrated that 1.5 at% Sn 2+ -NiO microspheres showed the highest response (∼25.2 ± 10%) to 200 ppm xylene, which was about 14-fold higher than that of the pure NiO. Moreover, the humidity-independent performance of the 1.5 at% Sn 2+ -NiO sample was excellent, such as low detection limit (1.1-500 ppb) and good selectivity toward xylene at high relative humidity (90% RH). The gas sensing mechanisms for the improved sensing performance were also discussed. [ABSTRACT FROM AUTHOR]

In this article, CeO 2 -based mixed potential type gas sensor attached with sensing electrodes (SEs) consisting of perovskite-type La 1-x Sr x CoO 3 (x = 0.1, 0.2, 0.3 and 0.5) composite oxides has been developed for acetone detection. The effect of different Sr 2+ doping content in La 1-x Sr x CoO 3 oxide material and calcination temperature on acetone sensing characteristics was investigated. It was seen that the sensor using La 0.8 Sr 0.2 CoO 3 calcined at 1000 °C as SE gave the largest sensing signal to acetone in the concentration range of 1–50 ppm at 600 °C among these sensors. The response value (ΔV) of the sensor was sectionally linearly changed with the logarithm of acetone concentration within the ranges of 1–5 ppm and 5–50 ppm, and the sensitivities were −26 and −49 mV/decade, respectively. In addition, it is noteworthy that the response of the sensor to 1 ppm acetone was approximately −8.7 mV. The sensor also exhibited consistent response and recovery characteristics in five cycles, indicating the sensing device had good reproducibility. Besides, the sensor exhibited the highest response to 10 and 50 ppm acetone and less effective response to other tested gases, it indicates that the sensor has good selectivity. Furthermore, the long-term stability for the sensor to 20 ppm acetone was good because that only a slight attenuation in the sensing response was observed during 30 days. The sensing characteristics of the sensor attached with La 0.8 Sr 0.2 CoO 3 -SE sintered at 1000 °C to acetone were explained in terms of electrocatalytic activity changes induced by effects of doped Sr divalent cation. [ABSTRACT FROM AUTHOR]