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Sotiris E Pratsinis - One of the best experts on this subject based on the ideXlab platform.
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silica is preferred over various single and mixed oxides as support for co2 assisted cobalt catalyzed oxidative dehydrogenation of ethane
Applied Catalysis A-general, 2016Co-Authors: Rajesh Koirala, Sotiris E Pratsinis, Robert Buechel, Alfons BaikerAbstract:Abstract Catalysts containing 4.5 wt% cobalt supported on single oxides of SiO2, Al2O3, TiO2 and ZrO2 and on mixed ones of SiO2-Al2O3, SiO2-TiO2, SiO2-ZrO2 and TiO2-ZrO2 were produced in a single step by Flame Spray pyrolysis and tested in the CO2-assisted oxidative dehydrogenation of ethane in a continuous fixed-bed microreactor. Structural and chemical properties of the nonporous catalysts were characterized by nitrogen adsorption, XRD, HR-TEM, EDXS, NH3-TPD, H2-TPR, TGA, DRIFTS, XPS and Raman and UV–vis spectroscopy. Depending on the supporting oxides the reducibility of the cobalt species varied in a broad range, indicating vastly different interaction of the cobalt species with the oxidic support. For catalysts supported on Al2O3 and SiO2-Al2O3 no significant H2 consumption was observed up to 840 °C, while ZrO2-supported CoOx was already reduced at T
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e nose sensing of low ppb formaldehyde in gas mixtures at high relative humidity for breath screening of lung cancer
ACS Sensors, 2016Co-Authors: Andreas T Guntner, Vitaly Koren, Kiran Chikkadi, Marco Righettoni, Sotiris E PratsinisAbstract:Formaldehyde (FA) is a potential breath marker for lung cancer and a tracer for indoor air quality monitoring. Its typical concentrations are below 100 ppb posing a sensitivity and selectivity challenge to current portable sensor systems. Here, we present a highly sensitive, selective, and compact electronic nose (E-nose) for real-time quantification of FA at realistic conditions. This E-nose consists of four nanostructured and highly porous Pt-, Si-, Pd-, and Ti-doped SnO2 sensing films directly deposited onto silicon wafer-based microsubstrates by Flame Spray pyrolysis (FSP). The constituent sensors offer stable responses (24 h tested) and detection of FA down to 3 ppb (signal-to-noise ratio > 25) at breath-realistic 90% relative humidity. Each dopant induces different analyte selectivity enabling selective detection of FA in two-, three- and four-analyte mixtures by multivariate linear regression. In simulated breath (FA with higher acetone, NH3, and ethanol concentrations), FA is detected with an aver...
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air entrainment during Flame aerosol synthesis of nanoparticles
Aerosol Science and Technology, 2014Co-Authors: Oliver Waser, Maximilian L Eggersdorfer, Arto J. Groehn, Sotiris E PratsinisAbstract:Enclosed Flames typically produce substantially larger particles than open Flames under identical reactant flows and composition. The enclosure hinders air entrainment to the Flame and reduces heat losses by radiation and convection, facilitating particle coagulation and coalescence. Here the effect of natural air entrainment on Flame aerosol synthesis is investigated by lifting off the enclosing tube from the burner surface and utilizing tracer gas (Ne) analysis after calibration with forced air entrainment. That way the effect of air entrainment on product primary particle diameter and mobility size distribution dynamics is investigated by microscopy, scanning mobility particle sizing, and N2 adsorption, while temperature is measured by Fourier-transform infrared spectroscopy. So air entrainment during Flame Spray pyrolysis is examined here for its versatility in scalable manufacture of an array of material compositions, while copper oxide (CuO) is used for its electro-chemical applications (e.g., batte...
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scale up of nanoparticle synthesis by Flame Spray pyrolysis the high temperature particle residence time
Industrial & Engineering Chemistry Research, 2014Co-Authors: Arto Juhani Grohn, Sotiris E Pratsinis, Antoni Sanchezferrer, Raffaele Mezzenga, Karsten WegnerAbstract:The scale-up of nanoparticle synthesis by a versatile Flame aerosol technology (Flame Spray pyrolysis) is investigated numerically and experimentally for production of ZrO2. A three-dimensional computational fluid dynamics model is developed accounting for combustion and particle dynamics by an Eulerian continuum approach coupled with Lagrangian description of multicomponent Spray droplet atomization, transport, and evaporation. The model allows the extraction of the high-temperature particle residence time (HTPRT) that is governed by the dispersion gas to precursor liquid mass flow ratio as well as the Flame enthalpy content. The HTPRT is shown to control the primary particle and agglomerate size, morphology, and even ZrO2 crystallinity in agreement with experimental data. When the HTPRT is kept constant, the production rate for ZrO2 nanoparticles could be scaled up from ∼100 to 500 g/h without significantly affecting product particle properties, revealing the HTPRT as a key design parameter for Flame ae...
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fluid particle dynamics during combustion Spray aerosol synthesis of zro2
Chemical Engineering Journal, 2012Co-Authors: Arto J Grohn, Sotiris E Pratsinis, Karsten WegnerAbstract:Abstract Owing to its versatility and low cost, Flame Spray pyrolysis (FSP) is becoming an increasingly promising method for industrial production of a broad spectrum of nanoparticles. To assist understanding and scale-up of the current laboratory process, a computational model has been constructed for the example of zirconia nanoparticle synthesis. Therefore, a computational fluid dynamics (CFD) description of the Spray Flame originating from a twin-fluid atomizer and coaxial diffusion burner was combined with droplet and nanoparticle dynamics. The model predicted well average primary ZrO 2 particle diameters even though global chemical reactions, immediate nanoparticle formation upon precursor oxidation and monodisperse particle dynamics were employed. This model is self-containing and does not rely on experimental input data such as temperature or velocity fields. The model was validated at different process conditions with phase-Doppler anemometry (PDA) for Spray characteristics, Fourier-transform infrared spectroscopy (FTIR) Flame temperature measurements as well as nanoparticle sampling in and above the Flame.
Lutz Madle - One of the best experts on this subject based on the ideXlab platform.
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the role of microexplosions in Flame Spray synthesis for homogeneous nanopowders from low cost metal precursors
Aiche Journal, 2016Co-Authors: Christophe D Rosebrock, Lutz Madle, Thomas Wried, Karste WegneAbstract:One of the most versatile and rapid manufacturing processes for a variety of nanopowders is Flame Spray pyrolysis (FSP). The production costs of this scalable process are largely controlled by the raw materials, pushing for the utilization of low-cost metal precursors. These, however, typically yield inhomogeneous products containing large particles up to micrometer size along with fine nanoparticles. Here, the release mechanism of nitrate and carboxylate precursors from Spray droplets has been investigated by single-droplet combustion experiments and thermogravimetric analysis. The results show that neither precursor evaporation nor choice of solvents is prerequisite for homogeneous nanopowders but droplet microexplosions with continuing combustion. It is shown that even low-cost metal nitrates yield homogeneous nanopowders if precursors are formulated such that droplet microexplosions occur by internal superheating. The proposed precursor release mechanisms are verified with lab- and pilot-scale FSP, demonstrating that single-droplet combustion experiments can be employed to predict the product quality. © 2015 American Institute of Chemical Engineers AIChE J, 2015
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Flame Spray pyrolysis for sensing at the nanoscale
Nanotechnology, 2013Co-Authors: J Kemmle, Lutz Madle, U Weima, Suma Pokhrel, Nicolae ArsaAbstract:Progress in developing novel gas sensors based on semiconducting metal oxides (SMOX) has been hindered by the cumbersome fabrication technologies currently employed. They involve time intensive synthesis procedures for gaining sensitive materials and preparation of the inks employed for realizing sensing layers. In this paper we review the opportunities offered by the relatively young method of Flame Spray pyrolysis, with which it is possible not only to synthesize a broad selection of SMOX in pure or doped form, but also to simultaneously deposit thick and highly porous gas sensitive films on a variety of substrates. In less than ten years the properties of nine base materials have been evaluated for all most relevant target gases and the obtained results are promising for future development.
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Flame Spray pyrolysis an enabling technology for nanoparticles design and fabrication
Nanoscale, 2010Co-Authors: Wey Yang Teoh, Rose Amal, Lutz MadleAbstract:Combustion of appropriate precursor Sprays in a Flame Spray pyrolysis (FSP) process is a highly promising and versatile technique for the rapid and scalable synthesis of nanostuctural materials with engineered functionalities. The technique was initially derived from the fundamentals of the well-established vapour-fed Flame aerosols reactors that was widely practised for the manufacturing of simple commodity powders such as pigmentary titania, fumed silica, alumina, and even optical fibers. In the last 10 years however, FSP knowledge and technology was developed substantially and a wide range of new and complex products have been synthesised, attracting major industries in a diverse field of applications. Key innovations in FSP reactor engineering and precursor chemistry have enabled flexible designs of nanostructured loosely-agglomerated powders and particulate films of pure or mixed oxides and even pure metals and alloys. Unique material morphologies such as core–shell structures and nanorods are possible using this essentially one step and continuous FSP process. Finally, research challenges are discussed and an outlook on the next generation of engineered combustion-made materials is given.
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sensing low concentrations of co using Flame Spray made pt sno2 nanoparticles
Journal of Nanoparticle Research, 2006Co-Authors: T Sahm, Lutz Madle, A Gurlo, Nicolae Arsa, U Weima, Jandierk Grunwald, Sotiris E PratsinisAbstract:Tin dioxide nanoparticles of different sizes and platinum doping contents were synthesized in one step using the Flame Spray pyrolysis (FSP) technique. The particles were used to fabricate semiconducting gas sensors for low level CO detection, i.e. with a CO gas concentration as low as 5 ppm in the absence and presence of water. Post treatment of the SnO2 nanoparticles was not needed enabling the investigation of the metal oxide particle size effect. Gas sensors based on tin dioxide with a primary particle size of 10 nm showed signals one order of magnitude higher than the ones corresponding to the primary particle size of 330 nm. In situ platinum functionalization of the SnO2 during FSP synthesis resulted in higher sensor responses for the 0.2 wt% Pt-content than for the 2.0 wt% Pt. The effect is mainly attributed to catalytic consumption of CO and to the associated reduced sensor response. Pure and functionalized tin dioxide nanoparticles have been characterized by Brunauer, Emmett and Teller (BET) surface area determination, X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy (STEM) while the platinum oxidation state and dispersion have been investigated by X-ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure (EXAFS). The sensors showed high stability (up to 20 days) and are suitable for low level CO detection: <10 ppm according to European and 50 ppm according to US legislation, respectively.
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nanorods of zno made by Flame Spray pyrolysis
Chemistry of Materials, 2006Co-Authors: Murray J Heigh, Sotiris E Pratsinis, Lutz Madle, Frank KrumeichAbstract:Inorganic nanorods with closely controlled aspect ratio were made by Flame Spray pyrolysis − a single-step, continuous, and scaleable process. Indium and tin dopants selectively affect a specific ZnO crystal plane and are incorporated into its lattice. Nanorod formation is attributed to the higher valency and coordination of indium and tin dopants relative to zinc and the associated disruption of crystal growth within the Zn plane. In contrast, lithium, with an equivalent ionic radius to these dopants but lower valency than zinc, has no effect on the ZnO texture. The formation of the nanorods within the Flame occurs by annealing crystallization during Flame cooling.
Richard M Laine - One of the best experts on this subject based on the ideXlab platform.
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photocatalytic la4ti3o12 nanoparticles fabricated by liquid feed Flame Spray pyrolysis
Ceramics International, 2020Co-Authors: Yoshiyuki Abe, Richard M LaineAbstract:Abstract Hexagonal plate-like nanoparticles (NPs) of the layered perovskite La4Ti3O12 were fabricated using liquid-feed Flame Spray pyrolysis (LF-FSP) followed by subsequent heat-treatments. Their photocatalytic activity was evaluated using decolorization of methyl orange solutions under Uv irradiation. LF-FSP combusts metalloorganic precursor aerosols to produce mixtures of cubic simple perovskite (ABO3) phase and lanthanum oxycarbonate (La2O4·846C0.846) phase with very low agglomeration and average particle sizes (APSs) of 23 nm (as-produced NPs). Rietveld refinement of synchrotron XRD powder patterns verified that the simple perovskite in the as-produced NPs is LaTiO3 (originally cubic Pm-3m-type space group) and heat-treating gives NPs of the trigonal layered perovskite La4Ti3O12 (R-3-type space group). La4Ti3O12 NPs heat-treated at 1100 °C/3-6h/air exhibits hexagonal plate-like morphology and high crystallinity offering enhanced photocatalytic degradation of methyl orange solutions compared to the as-produced NPs. The LF-FSP approach to obtaining layered perovskite La4Ti3O12 NPs provides a simple route to photocatalytic materials in reasonable quantities.
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liquid feed Flame Spray pyrolysis derived nanopowders nps as a route to electrically conducting calcium aluminate 12cao 7al2o3 films
Journal of The European Ceramic Society, 2019Co-Authors: Eleni Temeche, Vazrik Keshishia, Joh Kieffe, Richard M LaineAbstract:Abstract Traditionally, C12A7 materials have been processed via solid-state reaction followed by pulsed laser deposition (PLD) or floating zone (Fz) crystallization methods at high temperature, high cost approaches to single-phase films. These techniques require a significant number of process steps to generate C12A7:e− materials that have been shown to exhibit exceptional electrical conductivities as high as 1 S/cm. We demonstrate here an effective alternative method using Flame made C12A7 nanopowders (NPs) produced via liquid-feed Flame Spray pyrolysis (LF-FSP). Nearly fully dense, single phase, and transparent C12A7 films ( ℃ /3 h/O2. Subsequent heat treatments in 20/80 H2/N2 replaces cage trapped O2- ions forming C12A7:H− followed by UV irradiation to generate C12A7:e− with electrical conductivities of 35 mS cm-1. C12A7:e- appears to belong to a new class of transparent conducting oxides (TCOs) that may offer commercial potential on further optimization due to low materials and processing costs, environmental stability, and natural abundance when processed efficiently.
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processing liquid feed Flame Spray pyrolysis synthesized mg0 5ce0 2zr1 8 po4 3 nanopowders to free standing thin films and pellets as potential electrolytes in all solid state mg batteries
Electrochimica Acta, 2018Co-Authors: Vazrik Keshishia, Joh Kieffe, S Liu, Dechang Jia, Yu Zhou, Richard M LaineAbstract:Abstract Despite the intense concentration on lithium-based batteries, safety, ease of construction and cost continue to drive the search for alternatives that do not suffer from such restrictions. We present here preliminary work on the development of thin film Mg 2+ conducting electrolytes as the key starting point for the development of all-solid-state Mg batteries. Initial studies explored compositions in the Mg 0.5 Ce x Zr 2-x (PO 4 ) 3 (x = 0.1, 0.2 and 0.3) system first as pellets and with somewhat optimized compositions (with x = 0.2) as thin films. Introduction of Ce allows sintering to full density at temperatures where Ce free films do not densify completely. The work reported here relies on the synthesis of nanopowders (NPs) using liquid-feed Flame Spray pyrolysis that offers the potential to reduce processing conditions, to control final average grain sizes (AGSs) and provide single-phase materials with good to excellent mechanical properties. The pellets and then thin (≤50 μm) films produced here show conductivities of up to 3 × 10 −3 mS cm -1 at ≈ 300 °C, which if extrapolated (using an E a of ≈30) to 400 °C would be close to 10 −2 mS cm −1 in keeping with the best reported values in the literature. The thin films reported here offer nearly full densities beyond what is currently achievable by any other method. The ionic area specific resistance (IASR) values for these thin films were found to be 1400 Ω cm 2 at 300 °C and are estimated to drop to 110 Ω cm 2 at 400 °C, significantly lower than values for pellets reported elsewhere.
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high throughput screening of nanoparticle catalysts made by Flame Spray pyrolysis as hydrocarbon no oxidation catalysts
Journal of the American Chemical Society, 2009Co-Authors: M Reise, Klaus Stowe, Wilhelm F Maie, Mi Kim, Jose Azurdia, E Gulari, E Seke, Amanda K Arks, Richard M LaineAbstract:We describe here the use of liquid-feed Flame Spray pyrolysis (LF-FSP) to produce high surface area, nonporous, mixed-metal oxide nanopowders that were subsequently subjected to high-throughput scr...
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one step synthesis of core shell ce0 7zr0 3o2 x al2o3 1 x ce0 7zr0 3o2 al2o3 nanopowders via liquid feed Flame Spray pyrolysis lf fsp
Journal of the American Chemical Society, 2009Co-Authors: Mi Kim, Richard M LaineAbstract:We report here the synthesis of CexZr1−xO2 and (Ce0.7Zr0.3O2)x(Al2O3)1−x core−shell nanopowders in a single step by liquid-feed Flame Spray pyrolysis (LF-FSP) of the metalloorganic precursors, Ce(O2CCH2CH3)3(OH), alumatrane [N(CH2CH2O)3Al], and Zr(O2CCH2CH3)2(OH)2. Solutions of all three precursors in ethanol with ceramic yields of 2.5 wt% were aerosolized with O2, combusted at temperatures above 1500 °C, and rapidly quenched at ∼1000 °C/ms to form CexZr1−xO2 and (Ce0.7Zr0.3O2)x(Al2O3)1−x nanopowders of selected compositions, at rates of 50−100 g/h. The resulting, as-processed, materials are unaggregated nanopowders with average particle sizes (APSs) < 20 nm and corresponding specific surface areas of 30−50 m2/g. The as-processed powders were characterized in terms of phase, particle size, specific surface area, compositions, and morphology by XRD, BET, DLS, SEM, TEM, XPS, TGA-DTA, and FT-IR. LF-FSP provides access to binary CexZr1−xO2 nanopowders and ternary (Ce0.7Zr0.3O2)x(Al2O3)1−x nanopowders in one s...
Mahrukh Mahrukh - One of the best experts on this subject based on the ideXlab platform.
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effects of angular injection and effervescent atomization on high velocity suspension Flame Spray process
Surface & Coatings Technology, 2016Co-Authors: Mahrukh Mahrukh, Arvind Kumar, Sai GuAbstract:This work presents the nanostructured coating formation using suspension thermal Spraying through the HVOF torch. The nanostructured coating formation requires nanosize powder particles to be injected inside a thermal Spray torch using liquid feedstock. The liquid feedstock needs to be atomized when injected into the high-velocity oxygen fuel (HVOF) torch. This paper presents the effects of angular injection and effervescent atomization of the liquid feedstock on gas and droplet dynamics, vaporization rate, and secondary breakup in the high-velocity suspension Flame Spray (HVSFS) process. Different angular injections are tested to obtain the optimum value of the angle of injection. Moreover, effervescent atomization technique based on twin-fluid injection has been studied to increase the efficiency of the HVSFS process. Different solid nanoparticle concentrations in suspension droplets are considered. In angular injection the droplets are injected into the core of the combustion zone; this immediately evaporates the droplets, and evaporation is completed within the torch. The value of 10°–15° is selected as the optimal angle of injection to improve the gas and droplet dynamics inside the torch, and to avoid the collision with the torch's wall. The efficiency of the effervescent atomization can be enhanced by using high gas-to-liquid mass flow rate ratio, to increase the Spray cone angle for injecting the suspension liquid directly into the combustion Flame. It is also found that the increment in the nanoparticle concentration has no considerable effects on the droplet disintegration process. However, the location of evaporation is significantly different for homogeneous and non-homogeneous droplets.
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modeling the effects of concentration of solid nanoparticles in liquid feedstock injection on high velocity suspension Flame Spray process
Industrial & Engineering Chemistry Research, 2016Co-Authors: Mahrukh Mahrukh, Arvind Kumar, Sai Gu, Spyros Kamnis, Ebrahim GozaliAbstract:This paper presents the effects of the concentration of solid nanoparticles in the liquid feedstock injection on the high-velocity suspension Flame Spray (HVSFS) process. Four different concentrations of solid nanoparticles in suspension droplets with various droplet diameters are used to study gas dynamics, vaporization rate, and secondary breakup. Two types of injections, viz. surface and group, are used. The group-type injection increases the efficiency of droplet disintegration and the evaporation process and reduces the gas cooling. The initiation of the fragmentation process is difficult for small droplets carrying a high concentration of nanoparticles. Also, smaller droplets undergo rapid vaporization, leaving clogs of nanoparticles in the middle of the barrel. For larger droplets, severe fragmentation occurs inside the combustion chamber. For a higher concentration of nanoparticles, droplets exit the gun without complete evaporation. The results suggest that, in coating applications involving a hi...
Suko Phanichpha - One of the best experts on this subject based on the ideXlab platform.
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ultrasensitive no2 sensor based on ohmic metal semiconductor interfaces of electrolytically exfoliated graphene Flame Spray made sno2 nanoparticles composite operating at low temperatures
ACS Applied Materials & Interfaces, 2015Co-Authors: Nantika Tammanoo, A Wisitsoraa, Suko Phanichpha, Adiso Tuantrano, Chakri Sriprachuabwong, Ditsayu Phokharatkul, Chaika LiewhiraAbstract:In this work, Flame-Spray-made undoped SnO2 nanoparticles were loaded with 0.1–5 wt % electrolytically exfoliated graphene and systematically studied for NO2 sensing at low working temperatures. Characterizations by X-ray diffraction, transmission/scanning electron microscopy, and Raman and X-ray photoelectron spectroscopy indicated that high-quality multilayer graphene sheets with low oxygen content were widely distributed within spheriodal nanoparticles having polycrystalline tetragonal SnO2 phase. The 10–20 μm thick sensing films fabricated by spin coating on Au/Al2O3 substrates were tested toward NO2 at operating temperatures ranging from 25 to 350 °C in dry air. Gas-sensing results showed that the optimal graphene loading level of 0.5 wt % provided an ultrahigh response of 26 342 toward 5 ppm of NO2 with a short response time of 13 s and good recovery stabilization at a low optimal operating temperature of 150 °C. In addition, the optimal sensor also displayed high sensor response and relatively shor...
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photocatalytic activity under visible light of fe doped ceo2 nanoparticles synthesized by Flame Spray pyrolysis
Ceramics International, 2013Co-Authors: Suko Phanichpha, D Channei, Urapa Inceesungvo, Natda Wetchaku, A Nakaruk, Pramod Koshy, C C SorrellAbstract:Abstract CeO 2 nanoparticles (undoped and Fe-doped) were synthesised using Flame Spray pyrolysis with varying Fe-dopant concentrations. X-ray diffraction analysis revealed the absence of any impurity phases in all samples. BET (Brunauer, Emmett and Teller) tests showed that the average sizes of undoped and Fe-doped CeO 2 particles were 6.39 and 5.94 nm, respectively. Specific surface area of the particles increased with increasing Fe-dopant concentration. High resolution transmission electron microscopy (HRTEM) revealed that the nanoparticles were either spherical or equiaxed in shape. UV–vis spectroscopy showed a shift of the adsorption edge towards longer wavelengths along with a decrease in the optical indirect band gap from 3.18 to 2.90 eV for undoped particles and 2 mol% Fe-doped particles. In terms of photocatalytic performance, Fe-doped CeO 2 nanoparticles were responsible for an increased degradation of the carbon from formic and oxalic acids. Furthermore, the photocatalytic efficiency was ∼100% when 2 mol% Fe-doped CeO 2 particles were used for testing.
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ultra sensitive h2 sensors based on Flame Spray made pd loaded sno2 sensing films
Sensors and Actuators B-chemical, 2013Co-Authors: Chaika Liewhira, Nittaya Tamaekong, A Wisitsoraa, Adiso Tuantrano, Suko PhanichphaAbstract:Abstract In this paper, ultra-sensitive hydrogen (H 2 ) gas sensors based on Flame-Spray-made Pd-catalyzed SnO 2 nanoparticles is presented. Pd-loaded SnO 2 crystalline nanoparticles with high specific surface area and well-controlled size were synthesized by Flame Spray pyrolysis (FSP) in one step. The particle properties were characterized by XRD, BET, SEM, TEM and EDS analyses. The H 2 -sensing performances in terms of sensor response, response time and selectivity were optimized by varying Pd concentration between 0.2 and 2 wt%. An optimal Pd concentration for H 2 sensing was found to be 0.2 wt%. The optimal sensing film (0.2 wt% Pd/SnO 2 , 10 μm in thickness) showed an ultra-high sensor response of ∼10 4 to 1 vol% of H 2 at 200 °C and very short response time within a few seconds. Moreover, the optimum sensing temperature of Pd-loaded SnO 2 films was shifted to a lower value compared with that of unloaded SnO 2 film. The significant enhancement of H 2 sensing performances was attributed to highly effective spillover mechanism of well-dispersed Pd catalyst in SnO 2 matrix at low Pd-loading concentration. Furthermore, the catalyst selectivity of Pd toward H 2 was found to be significantly higher than those of two other noble metals including Pt and Ru, respectively. Therefore, the Flame-made 0.2 wt% Pd/SnO 2 sensors is one of the most promising candidates for highly sensitive and selective detection of H 2 .
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Flame Spray made metal loaded semiconducting metal oxides thick films for flammable gas sensing
Sensors and Actuators B-chemical, 2012Co-Authors: T Samerjai, Nittaya Tamaekong, Chaika Liewhira, A Wisitsoraa, Khatchari Wetchaku, Viruntacha Kruefu, Chawara Siriwong, Suko PhanichphaAbstract:Abstract Flame Spray pyrolysis (FSP) presents a new technique for metal (Pt, Sn, Ru, Nb and W)-loaded metal oxide (MOX) nanoparticle synthesis, which requires only a single step. FSP prepared MOX nanoparticles have recently widely employed for gas-sensing applications. In this work, the performance towards flammable gases of unloaded and metal (Pt, Sn, Ru, Nb and W)-catalyzed metal oxide (ZnO, WO 3 , SnO 2 and TiO 2 ) nanoparticle thick films fabricated by FSP and spin-coating is reviewed, discussed and compared to MOXs prepared by other methods. The gas-sensing characteristics towards H 2 , CH 4 , C 2 H 2 , C 2 H 4 , C 2 H 5 OH and CO gases of FSP-prepared MOXs are found to be significantly improved in terms of response, response time and selectivity with small Pt, Sn, Ru, Nb and W loading contents ranging from 0.2 to 5 mol% or at.%. In addition, Pt loading on WO 3 and ZnO sensors results in excellent detection performances towards several flammable gases including H 2 , CH 4 and C 2 H 2 .
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highly selective environmental sensors based on Flame Spray made sno2 nanoparticles
Sensors and Actuators B-chemical, 2012Co-Authors: Chaika Liewhira, Nittaya Tamaekong, A Wisitsoraa, Suko PhanichphaAbstract:Abstract Flame-Spray-made SnO 2 thick films fabricated by spin coating method were studied for toxic and flammable gas-sensing applications. From physical characterization by X-ray diffraction, Brunauer–Emmett–Teller analysis, scanning and transmission electron microscopy, SnO 2 nanoparticles were found to have non-agglomerated spherical, hexagonal, rectangle (3–10 nm), and rod-like (3–5 nm in width and 5–20 nm in length) morphologies with large specific surface area of 141.6 m 2 /g. The sensing films were prepared by spin coating on Al 2 O 3 substrate with interdigitated Au electrode. The sensing films were tested toward some important toxic (NO 2 , CO, SO 2 ) and flammable (H 2 , C 2 H 2 ) gases. It was found that SnO 2 sensing film showed excellent response and selectivity for NO 2 at a low operating temperature of 200 °C. In addition, the response linearly increased and the response time drastically decreased with increasing gas concentration. Therefore, the spin-coated Flame-Spray-prepared SnO 2 sensor is one of the most promising candidates for highly sensitive and selective detection of noxious NO 2 gas.