LPG Detection Research Articles

Preparation of MnO2 immobilized graphene nanocomposite by solid state diffusion route for LPG sensing

Sensor based on MnO2/graphene nanocomposite has been fabricated and tested for LPG detection. Structure and morphology of composite was analyzed through X-ray diffraction and field emission-electron microscopy. The optical properties were studied through ultraviolet–visible and fluorescence spectroscopy. The MnO2/graphene nanocomposite based sensor exhibits significant sensing response at low operating temperature including good stability and fast response and recovery time. This work successfully fulfilled its objectives in developing novel resistive gas sensor.

Sensitivity Enhancement for LPG Detection by Employing Cadmium Oxide Doped in Nanocrystalline Polyaniline

Sensitivity Enhancement for LPG Detection by Employing Cadmium Oxide Doped in Nanocrystalline Polyaniline

Selective gas sensing response from different loading of Ag in sol–gel mesoporous titania powders

Bare and Ag loaded TiO 2 (0.05, 0.5, and 5.0 mol% Ag) powders prepared by sol–gel process have been used for the detection of ethanol, LPG, acetone and toluene gases. These materials were well characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) specific surface area analysis techniques. Specific surface area increased with increasing Ag loading in these mesoporous materials. A thorough TEM/HRTEM investigation with X-ray maps of the modified particles shows the extent of TiO 2 surface coverage by Ag nanoparticles. From the comparative study of the sensor response of Ag–TiO 2 powders for various gases, it is observed that each Ag loading resulted in the highest response towards a particular gas or in other words, every gas responded best towards a particular Ag loading of the sensor material, i.e. 0.05 mol% Ag–TiO 2 sensor showed highest response towards ethanol, 0.5 mol% Ag–TiO 2 sensor showed best response towards toluene, whereas, bare TiO 2 proved to be the best sensor for both acetone and LPG gases. This establishes that Ag loading is not required for detection of acetone and LPG gases. On the basis of detailed materials characterization, a mechanism for the gas sensing response of each analyte has been discussed.

Effect of thickness of thin film SnO2 based LPG sensors

ABSTRACTThis paper reports the response characteristics of rf-sputtered SnO2 thin films (of varying thickness) for LPG detection. To monitor and precisely measure leakages, the development of a reliable LPG sensor with improved sensitivity is crucial in preventing fatal accidents. In the present study, thin film of SnO2 is used as the sensing element for LPG sensor. The thickness of a thin film is a very important parameter and determines their main operating characteristics, such as sensor response, rate of response, and working temperature. In the present study, thickness of SnO2 film is varied between 30 nm to 180 nm. The structure, composition and optical properties of SnO2 thin films have been examined by XRD, SEM, AFM and UV-Vis. The crystallite size for 90 nm thin film (for (110) plane) is found to be the smallest ~4-5 nm. Sensor response $(S = \left( {{{R_a - R_g } \over {R_a }}} \right) \times 100\% )$ increases with thickness of the sensing film, with a highest sensor response (~67%) observed for 90 nm thin film and thereafter it decreases. The structural and optical properties clearly support the observed enhanced sensor response for 90 nm thin film.

Nanostructured spinel ZnCo 2O 4 for the detection of LPG

Nanostrucutred spinel ZnCo 2O 4 (∼26–30 nm) was synthesized by calcining the mixed precursor (consisting of cobalt hydroxyl carbonate and zinc hydroxyl carbonate) in air at 600 °C for 5 h. The mixed precursor was prepared through a low cost and simple co-precipitation/digestion method. The transformation of the mixed precursor into nanostructured spinel ZnCo 2O 4 upon calcinations was confirmed by X-ray diffraction (XRD) measurement, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM). To demonstrate the potential applicability of ZnCo 2O 4 spinel in the fabrication of gas sensors, its LPG sensing characteristics were systematically investigated. The ZnCo 2O 4 spinel exhibited outstanding gas sensing characteristics such as, higher gas response (∼72–50 ppm LPG gas at 350 °C), response time (∼85–90 s), recovery time (∼75–80 s), excellent repeatability, good selectivity and relatively lower operating temperature (∼350 °C). The experimental results demonstrated that the nanostructured spinel ZnCo 2O 4 is a very promising material for the fabrication of LPG sensors with good sensing characteristics. Plausible LPG sensing mechanism is also discussed.

Enhanced room temperature response of SnO 2 thin film sensor loaded with Pt catalyst clusters under UV radiation for LPG

The room temperature response characteristics of SnO 2 thin film sensor loaded with platinum catalyst clusters are investigated for LPG under the exposure of ultraviolet radiation. The SnO 2-Pt cluster sensor structures have been prepared using rf sputtering. Combined effect of UV radiation exposure ( λ = 365 nm) and presence of Pt catalyst clusters (10 nm thick) on SnO 2 thin film sensor surface is seen to lead to an enhanced response (4.4 × 10 3) for the detection of LPG (200 ppm) at room temperature whereas in the absence of UV illumination a comparable response (∼5 × 10 3) could be obtained but only at an elevated temperature of 220 °C. The present study therefore investigates the effect of UV illumination on LPG sensing characteristics of SnO 2 sensors loaded with Pt clusters of varying thickness values. Results indicate the possibility of utilizing the sensor structure with novel dispersal of Pt catalyst clusters on SnO 2 film surface for efficient detection of LPG at room temperature under the illumination of UV radiations.

Effect of thickness of platinum catalyst clusters on response of SnO 2 thin film sensor for LPG

This paper reports the sensing response characteristics of rf-sputtered SnO 2 thin films (90 nm thick) loaded with platinum catalyst cluster of varying thickness (2–20 nm) for LPG detection. The enhanced response (5 × 10 3) was obtained for 200 ppm LPG with the presence of 10 nm thin and uniformly distributed Pt catalyst clusters on the surface of SnO 2 thin film at a relatively low operating temperature (220 °C). The high response for LPG is shown to be primarily due to the enhanced catalytic activity for adsorbed oxygen on the surface of SnO 2 thin film besides the spill over mechanism at elevated temperature.

Sensing mechanism of Pd-doped SnO 2 sensor for LPG detection

In the present work, studies have been made to analyze the sensitivity, response, recovery time and sensing mechanism of Pd-doped thick film SnO 2 sensor for detection of LPG. To achieve this, thick film Pd-doped (0.25 and 1% by weight in available Indium doped SnO 2 thick film paste supplied by ESL, USA) along with an undoped (Indium doped) SnO 2 sensors were fabricated on a 1″ × 1″ alumina substrate. It consists of a gas sensitive layer (doped SnO 2), a pair of electrodes underneath the gas sensing layer serving as a contact pad for sensor. Also, a heater element on the backside of the substrate was printed for generating appropriate operating temperature at the substrate necessary for acquiring gas sensing properties. The sensor doped with 1% palladium showed the maximum sensitivity of 72% at 350 °C for 0.5% concentration of LPG. Possible detailed sensing mechanism of Pd-doped SnO 2 sensor for LPG detection has been proposed.

Enhanced LPG response characteristics of SnO2 thin film based sensors loaded with Pt clusters

Abstract RF sputtered SnO2 thin films (90 nm thick) loaded with clusters of nanoscale (8 nm) metal catalysts (Pt, Ag, Ni, Pb, Al, Pd) are investigated for LPG detection. SnO2 film loaded with Pt catalyst clusters exhibits enhanced response (~ 7.5×102) to 200 ppm of LPG at a relatively low operating temperature (185oC) with a fast response time of 100s. Variation of thickness of Pt clusters in the nanoscale range (2 to 20 nm) is seen to significantly influence the sensor response characteristics. Enhanced performance is observed for SnO2 thin films loaded with 10 nm thick platinum clusters that exhibited a high response (~ 5 x 103) at an operating temperature, of 220° C. Preliminary results indicate the potential application of prepared sensor structure of Pt clusters (10nm)/SnO2 (90 nm)/IDE/glass substrate for efficient detection of LPG at relatively low temperature.

Enhanced catalytic activity of nanoscale platinum islands loaded onto SnO2 thin film for sensitive LPG gas sensors

In the present study, different catalysts (∼ 10 nm thick) including metals, noble metals and metal oxides, were loaded in dotted island form over SnO2 thin film for LPG gas detection. A comparison of various catalysts indicated that the presence of platinum dotted islands over SnO2 thin film deposited by r.f. sputtering exhibited enhanced response characteristics with a high sensitivity, ∼ 742, at an operating temperature of ∼ 280°C. Different characterization techniques have been employed such as atomic force microscopy, X-ray diffraction and UV-vis spectroscopy, to study the surface morphology, grain size and optical properties of the deposited thin films. The results suggest the possibility of utilizing the sensor element with the present novel method of catalyst dispersal for the efficient detection of LPG.

Improved response characteristics of SnO2 thin film loaded with nanoscale catalysts for LPG detection

This paper reports the response characteristics of rf-sputtered SnO 2 thin films (90 nm thick) loaded with nanoscale catalysts for LPG detection. Ultrathin (8 nm) layers of various metal catalysts (Pt, Ag, Ni, Pb) and their respective oxides are loaded over the SnO 2 surface in the form of dotted islands. All sensor structures prepared with catalysts show higher sensor resistance in air and are attributed to the difference in the work function of the metal catalysts with respect to the underneath SnO 2 layer. A SnO 2 film with Pt-dotted islands is found to exhibit an enhanced response of about 750 for100 ppm of LPG at a relatively low operating temperature (260 °C) with a fast response time of 100 s. The high response is shown to be primarily due to dominant roles played by both Fermi energy control mechanism and spillover mechanism. The results suggest the possibility of utilizing the sensor structure having novel dispersal of Pt catalyst on the SnO 2 film surface for efficient detection of LPG.

Studies on pyrolytically sprayed SnO2 and Sb-SnO2 thin films for LPG sensor applications

Undoped and antimony doped tin oxide thin films of different thicknesses were prepared on mineral glass substrate by spray pyrolysis method via sol-gel route. Both the films show good transmittance in the visible region. Band gap energy of both films lies between 3 to 3.5 eV. X-ray diffraction studies of undoped and antimony doped tin oxide thin films for various annealing temperature show polycrystalline tetragonal structure of SnO2 with preferred orientation of (110) and (101), respectively and from the XRD data, grain size were also evaluated. AFM images of Undoped and antimony doped tin oxide thin films annealed at 375 °C depict the film thickness and indicate uniform surface pattern without dark pits and with strains of some ups exceeding the specified limit. The prepared films were tested in a specially developed test rig for Liquefied Petroleum Gas detection at different operating temperatures. The response characteristics of the films for LPG detection show maximum sensitivity and minimum response time at the operating temperature 400 °C. Studies indicate that antimony doped tin oxide thin film are one among the suitable candidates for LPG detection with a detection sensitivity and response time (t90) of 11 and 140 seconds, respectively.

E-beam deposited SnO2, Pt–SnO2 and Pd–SnO2 thin films for LPG detection

The electron-beam evaporation method was used to deposit undoped and Pt (or Pd) doped SnO2 thin films. After careful study of their physical properties, SnO2 thin films with suitable growth conditions were selected for probing their response to LPG and other common household gases. The response behaviour is explained with the help of theoretical models. Based on these results, the optimum parameters for film growth and sensor operation were identified for LP gas detection.