Browsing by Author "Huang, Zhaorong"

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    Accurate measurement of the piezoelectric coefficient of thin films by eliminating the substrate bending effect using spatial scanning laser vibrometry
    (Institute of Physics, 2010-06-30T00:00:00Z) Leighton, Glenn J. T.; Huang, Zhaorong
    One of the major difficulties in measuring the piezoelectric coefficient d(33,f) for thin films is the elimination of the contribution from substrate bending. We show by theoretical analysis and experimental measurements that by bonding thin film piezoelectric samples to a substantial holder, the substrate bending can be minimized to a negligible level. Once the substrate bending can be effectively eliminated, single-beam laser scanning vibrometry can be used to measure the precise strain distribution of a piezoelectric thin film under converse actuation. A significant strain increase toward the inside edge of the top electrode (assuming a fully covered bottom electrode) and a corresponding strain peak in the opposite direction just outside the electrode edge were observed. These peaks were found to increase with the increasing Poisson's ratio and transverse piezoelectric coefficient of the piezoelectric thin film. This is due to the non-continuity of the electric field at the edge of the top electrode, which leads to the concentration of shear stress and electric field in the vicinity of the electrode edge. The measured d(33,f) was found to depend not only on the material properties such as the electromechanical coefficients of the piezoelectric thin films and elastic coefficients of the thin film and the substrate, but also on the geometry factors such as the thickness of the piezoelectric films, the dimensions of the electrode, and also the thickness of the substrate.
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    Aerogel/epoxy thermal coatings for carbon fibre reinforced plastic substrates
    (Taylor and Francis, 2019-01-20) Krishnaswamy, Suryanarayanan; Abhyankar, Hrushikesh; Marchante, Veronica; Huang, Zhaorong; Brighton, James
    The present work studies an aerogel/epoxy composite that was dip coated onto a carbon fibre substrate by adding the aerogel at the 1 h and the 1.5 mark of the epoxy cure. Both coatings show decrease in thermal conductivity values (39% and 47% respectively) when compared to a pure epoxy coating. The coatings’ reflectance spectra also provided further evidence for the existence of the nano-pores within the aerogel particles. The aerogel coating was modelled using material properties from literature and solved using finite element methods. The model, which validated using experimental data, was then used to predict the coating’s performance in cyclic thermal loads. Additionally, coatings on a single surface- top and bottom; were also modelled and compared with the double coating system wherein it was seen that the double coating system had the lowest rate of temperature change and fluctuations at steady-state in contrast to the bottom coating which, showed the fastest drop in temperature as well as the highest fluctuations at steady state conditions. The performance of the top coating was in the middle.
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    Comparative studies of PST thin films as prepared by Sol-Gel, LDCVD and sputtering techniques
    (Taylor and Francis, 2002) Huang, Zhaorong; Donohue, P. P.; Zhang, Qi; Williams, D.; Anthony, C. J.; Todd, M. A.; Whatmore, Roger W.
    Lead scandium tantalate (PST) thin films for pyroelectric applications have been deposited by using liquid delivery chemical vaporise deposition (LDCVD), sputtering and sol-gel techniques. These films were annealed by using rapid thermal annealing to improve their electrical properties. Their microstructures and electrical properties such as permittivity εr, dielectric loss tanδ, pyroelectric coefficient p, and thermal detection figure of merit Fd were studied. It is suggested to use a combination of methods to depositing films and then use rapid thermal annealing to produce high quality PST thin films.
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    Coupled piezoelectric fans with two degree of freedom motion for the application of flapping wing micro aerial vehicles
    (Elsevier Science B.V., Amsterdam., 2008-10-03T00:00:00Z) Chung, H. C.; Lal Kummari, K.; Croucher, S. J.; Lawson, Nicholas J.; Guo, Shijun J.; Huang, Zhaorong
    Piezoelectric fans consisting of a piezoelectric layer and an elastic metal layer were prepared by epoxy bonding and a coupled flexible wing was formed by a pair of carbon fibre reinforced plastic wing spars and polymer skin attached to two piezoelectric fans. Two sinusoidal voltages with phase differences were then used to drive the coupled piezoelectric fans. High speed digital cameras were used to characterize the two degree of freedom (DOF) motion of the wing and these results were compared to finite element model of the wing and the coupled piezoelectric fans. It has been observed that the phase delay between the driving voltages applied to the coupled piezoelectric fans plays an important role in the control of the flapping and twisting motions of the wing and this set-up has the potential for application to the control of flapping wings for micro aerial vehicles. (c) 2008 Elsevier B.V. All rights reserved.
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    Data for the paper "UV Treatment of Flexible Copper Nanowire Mesh Films for Transparent Conductor Applications"
    (Cranfield University, 2017-11-01 10:07) Lonne, Quentin; Endrino Armenteros, Jose; Huang, Zhaorong
    Data used in the accompanying paper.
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    Development of piezoelectric actuated mechanism for flapping wing micro-aerial vehicle applications
    (Maney Publishing, 2010-03-31T00:00:00Z) Lal Kummari, K.; Li, Daochun; Guo, Shijun J.; Huang, Zhaorong
    A piezoelectric actuated two-bar two-flexure motion amplification mechanism for flapping wing micro-aerial vehicle application has been investigated. f(r)*A as an optimisation criterion has been introduced where f(r) is its fundamental resonant frequency of the system and A the vibration amplitude at the wing tip, or the free tip deflection at quasi-static operation. This criterion can be used to obtain the best piezoelectric actuation mechanism with the best energy transmission coefficient for flapping wing micro-aerial vehicle applications, and is a measurable quantity therefore can be compared with experimental results. A simplified beam model has been developed to calculate the fundamental resonant frequency for the full system consisted of piezoelectric actuator, motion amplification mechanism and the attached wing and the calculated values were compared with the measured results. A clear trend of the criteria f(r)*A varying with the two-flexure dimension, stiffness and setting angle have been obtained from the measured data and also the predicted results as a guideline for optimal design of the system.
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    Direct and converse magnetoelectic effect in laminate bonded Terfenol-D-PZT composites
    (Elsevier Science B.V., Amsterdam., 2007-09-20T00:00:00Z) Record, P. M.; Popov, C.; Fletcher, J.; Abraham, E.; Huang, Zhaorong; Chang, Harrison Hoon Seok; Whatmore, Roger W.
    Results from measurements of the direct and converse magnetoelectric (ME) effect on a three-layer, epoxy-bonded, laminate composite are presented. The laminae are a single transversely polarized piezoelectric elements (PZ29) sandwiched between two longitudinal-magnetic ally polarized magnetostrictive TD elements (Terfenol-D-TX GMM). The direct ME effect was determined by measuring laminate output with a Helmholtz-generated AC field (up to 7 Oe) in the range 50 Hz-100 kHz biased by a DC field (0-1000 Oe). Peak voltage output occurred at the sample's mechanical resonant frequency, its value depending on the strength and direction of the applied magnetic field. The peak output was 3061 mV at 3 Oe AC field and 1000 Oe bias, equivalent to 74.4 V cm(-1) Oe(-1). The peak output coefficient, however, was 93.6 V cm(-1) Oe(-1) at 0.1 Oe AC field and 1000 Oe DC bias. The reduction at higher drive amplitudes was attributed to increased Young's modulus of the TD phase. Anomalous peaks in the low frequency spectrum of sample's output are explained. The converse magnetoelectric effect was measured by recording the voltage induced in a solenoid encompassing the ME while exposed to a DC bias field and the PZ phase driven by a 10 VAC source. The peak output is shown to depend on the strength of the applied DC magnetic field and developed a maximum field of 15.4 Oe at the sample's mechanical resonant frequency. This equates to a converse magnetoelectric coefficient of 55 Oe cm kV (-1) (c) 2007 Elsevier B.V. All rights reserved.
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    Direct and converse magnetoelectric effect at resonant frequency in laminar piezoelectric-magnetostrictive composite.
    (Springer Science Business Media, 2008-02-01T00:00:00Z) Popov, C.; Chang, Harrison Hoon Seok; Record, P. M.; Abraham, E.; Whatmore, Roger W.; Huang, Zhaorong
    Laminar piezoelectric-magnetostrictive composites using piezoelectric lead zirconate titanate ceramics and the giant magnetostrictive rare-earth-iron alloy Terfenol-D were prepared by epoxy bonding. The direct and converse magnetoelectric (ME) effects at and off the mechanical resonant frequency were characterized and compared to the theoretical modelling. The mechanical resonant frequency of the composites depended on the sample orientation and the magnetic DC bias field. In the longitudinal configuration, the resonant frequency shifted down monotonically with the increasing bias field. When the sample was in the transverse configuration, the resonant frequency decreased with the increasing field at first. However, at higher bias, it shifted up with the increasing bias. A phenomenological model based on the à  E effect of magnetostrictive materials is proposed to explain the observed phenomena
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    Effect of extrusion and compression moulding on the thermal properties of nylon-6/silica aerogel composites
    (SAGE, 2017-10-03) Krishnaswamy, Suryanarayanan; Tinsley, Lawrence; Marchante, Veronica; Addepalli, Sri; Huang, Zhaorong; Abhyankar, Hrushikesh
    The article presents the effect of a lower extrusion speed and compression moulding processes on the thermal properties of polyamide 6 (PA-6)/aerogel composite. Scanning electron and optical microscope images showed that although most of the aerogel was destroyed during extrusion at 65 r/min, extrusion at 5 r/min showed a better retention of the aerogel structure. However, when subjected to moulding in a compression press, both composites extruded at different speeds suffered significant damage. Nevertheless, the extruded samples did show a lower thermal conductivity compared to the virgin polymer. Further, it was observed that the sample extruded at 5 r/min had a lower damage coefficient value with an overall loss of around 33% to the aerogel structure when compared to the material extruded at 65 r/min, which endured a structural loss of 41% to the aerogel in it.
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    Effect of extrusion and compression moulding on the thermal properties of Nylon-6/Silica Aerogel Composites: Experimental Data
    (Cranfield University, 2017-10-05 16:38) Krishnaswamy, Surya; Tinsley, Lawrence; Marchante, Veronica; Addepalli, Sri; Huang, Zhaorong; Abhyankar, Hrushikesh
    The paper presents the effect of a lower extrusion speed and compression moulding on the thermal properties of PA-6/Aerogel composite. SEM/EDX and optical microscope images showed that although most of the aerogel was destroyed during extrusion at 65 rpm, extrusion at 5 rpm showed better retention of the aerogel structure. However, when subjected to moulding in a compression press, both composites suffered significant damage. Nevertheless, the final thermal conductivity and damage coefficient values did show an improvement in the thermal insulation properties of the samples extruded at 5 rpm compared to the samples extruded at 65 rpm and the virgin polymer (PA-6) with the former losing around 33% of the structure of the aerogel particles compared to 41% for the later.
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    Effect of plasma processing parameters on the surface modification of fibre reinforced composites by atmospheric pressure plasma treatment
    (euspen, 2021-06-10) Frumosu, Lydia; Bishop, Alex; Castelli, Marco; Bennett, Adam; Nicholls, John R.; Huang, Zhaorong
    This report presents a study on the effect of microwave plasma sources on the surface modification of carbon fibre reinforced composites. The adhesion property of polymer composites is an important consideration in manufacturing processes. A key challenge in polymer adhesion is the need for adhesive pre-treatment to improve the wettability properties of the surface. Often three sequential steps are needed: contaminant removal, physically induced surface modification and chemical treatment. Atmospheric plasma treatment (APT) has been shown to either achieve, or eliminate the need for, one or more of these steps. The effects of APT on the surface properties of thermoplastics and thermosetting polymers have been reported recently, but the report on the effect of different plasma sources on the APT of polymers is limited. 50% carbon fibre epoxy samples were subjected to a microwave plasma source with varied flow rate, power, and samples’ distance from source, under atmospheric conditions. The surface energy of the composites was determined using liquid contact angle analysis. A coherence scanning interferometer was used to characterise the surface changes. The underlying mechanisms for the observed change of surface properties will be discussed.
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    Enhanced pyroelectric effect through product property and its applications
    (Cranfield University, 2009-10) Chang, Harrison Hoon Seok; Huang, Zhaorong
    Pyroelectric materials have the ability to generate electrical response when they experience a thermal stimulus. This has lead to their deployment in applications such as Infra-Red detectors/sensors, energy harvesting, and ferroelectric electron emission cathodes, among others. All the “Figures of merit” presented in the literature for assessing pyroelectric materials are proportional to the pyroelectric coefficient. Hence, enhancing this coefficient should improve the performance of the pyroelectric element in any application. This research has been conducted to find ways of enhancing the pyroelectric coefficient of a given material through product property in the secondary pyroelectric effect arising from thermal expansion coefficient mismatch. Analytical model for describing such enhancement in 2-2 connectivity laminate composites has been developed and simulated on Mathematics package Maple, while Finite Element Analysis package ANSYSR⃝ was used to perform thermo-structural analysis investigating the effect of bonding/interfacial layer on the strain transfer between the laminate layers. Indicators for judging the credentials of various pyroelectric materials in pyroelectric coefficient enhancement have been identified and evaluated for six different pyroelectric materials. These six pyroelectric materials were paired with six different non-pyroelectric materials to form thirty-six 2-2 connectivity laminate composites for the purpose of comparing pyroelectric coefficient enhancements, whereby various factors affecting the enhancement have been determined. Potential applications of this enhancement and what it may mean in terms of improvement in the outputs of these applications has been reviewed. In particular, two electrical boundary conditions, namely short and open circuit conditions, have been explored while the effects of thermal mass variation due to the introduction of non-pyroelectric layer have also been inspected. Experimental verification of pyroelectric coefficient enhancement under short circuit condition in Lead zirconate titanate/Stainless steel 2-2 connectivity laminate composites has been conducted with observed pyroelectric coefficient enhancements of more than 100 % while theoretical enhancements of up to 800 % is predicted in certain laminate composites of Lead zirconate titanate/Chlorinated polyvinyl chloride thermoplastic. Consideration of the open circuit condition pyroelectric coefficients and their enhancements revealed significant dissimilarities from their short circuit condition counterparts, prompting the need for more distinction to be made between the two than it has previously been thought. For instance, appraising employment credentials of pyroelectric elements in applications such as pyroelectric X-ray generation, electron accelerator, and nuclear fusion should involve the use of open circuit pyroelectric coefficient rather than the short circuit one. The effects of thermal mass has also been considered using quantities termed “Figures of merit for efficiency”, comparing the laminate composite’s thermal-to-electrical conversion efficiency to that of stand alone pyroelectric material. Up to twenty fold increase in thermal-to-electrical conversion efficiency under short circuit condition has been predicted in laminate composites of Lead zirconate titanate/Chlorinated polyvinyl chloride thermoplastic, insinuating a potential for increased employment of Lead zirconate titanate in areas such as pyroelectric sensors and pyroelectric energy harvesting. Pyroelectric energy harvesting application has been examined in detail as a potential beneficiary of this enhancement, with various analysis tools for assessing pyroelectric energy harvesting performance of a given pyroelectric element presented and evaluated. A pyroelectric energy harvesting system was designed as a hypothetical application of pyroelectricity and pyroelectric coefficient enhanced 2-2 connectivity laminate composites. Theoretical analysis confirms that large improvement in pyroelectric energy harvesting performance can be expected in Lead zirconate titanate materials by converting them into 2-2 connectivity laminate composites. The use of newly defined “New electrothermal coupling factor for composites” (k2 N ew) for assessing credentials of particular pyroelectric element in pyroelectric energy harvesting application has been proposed and vindicated while the experimental samples from the pyroelectric coefficient enhancement study were demonstrated to show significant improvement in their pyroelectric energy harvesting performance via pyroelectric coefficient enhancement. The analysis techniques used in this dissertation provide a methodology for assessing the potentials of particular pyroelectric material and its 2-2 connectivity laminate composites for applications under both short and open circuit conditions.
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    Enhanced thermoelectric performance of Cs doped BiCuSeO prepared through eco-friendly flux synthesis
    (Elsevier, 2017-11-10) Abdenour, Achour; Chen, Kan; Reece, Michael J.; Huang, Zhaorong
    The synthesis of BiCuSeO oxyselenides by a flux method in air has been investigated. A maximum power factor of 230 μWm−1K−2 and a very low thermal conductivity of 0.42 Wm−1K−1 were obtained, leading to a high ZT value of 0.37 at 680 K for pristine BiCuSeO. With Cs doping, a large enhancement in electrical conductivity coupled with a moderate decrease in Seebeck coefficient lead to a power factor of 340 μWm−1K−2 at 680 K. In addition, Cs doping reduced the thermal conductivity further to 0.35 Wm−1K−1 at 680 K. The combination of higher power factor and reduced thermal conductivity results in a high ZT value of 0.66 at 680 K for Bi0.995Cs0.005CuSeO.
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    Fabrication of continuous ultrathin ferroelectric films by chemical solution deposition methods
    (Materials Research Society, 2008-10) Ricotea, J.; Holgado, S.; Huang, Zhaorong; Ramos, P.; Fernandez, R.; Calzada, M. L.
    The integration of ferroelectrics in nanodevices requires firstly the preparation of high-quality ultrathin films. Chemical solution deposition is considered a rapid and cost-effective technique for preparing high-quality oxide films, but one that has traditionally been regarded as unsuitable, or at least challenging, for fabricating films with good properties and thickness below 100 nm. In the present work we explore the deposition of highly diluted solutions of pure and Ca-modified lead titanates to prepare ultrathin ferroelectric films, the thickness of which is controlled by the concentration of the precursor solution. The results show that we are able to obtain single crystalline phase continuous films down to 18 nm thickness, one of the lowest reported using these methods. Below that thickness, the films start to be discontinuous, which is attributed to a microstructural instability that can be controlled by an adequate tailoring of the processing conditions. The effect of the reduction of thickness on the piezoelectric behavior is studied by piezoresponse force microscopy. The results indicate that films retain a significant piezoelectric activity regardless of their low thickness, which is promising for their eventual integration in nanodevices, for example, as transducer elements in nanoelectromechanical systems.
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    Feasibility of an electrostatic energy harvesting device for CFCs aircraft
    (Elsevier, 2015-02-14) Xie, Huiling; Huang, Zhaorong; Guo, Shijun J.; Torru, Ekiyor
    A novel energy harvesting concept is proposed for treating local electrostatic energy produced on flying composite aircrafts. This work focuses on the feasibility research on collecting static charges with capacitive collectors. The existing energy harvesting system and the electrification of the typical carbon fibre composites (CFCs) aircraft has been reviewed. The detailed model experiments were then designed to characterize different configurations for electrostatic energy harvesting on aeroplane. In the lab, the static charge was produced by a corona discharging device, and a capacitor or a metal sheet was put in the electric field to collect the charges under four different configurations. After that, the rest results for these configurations were analysed, which is followed by the discussion about the results application on the aircraft. This work has proved that it is feasible to collect the local static electricity on flying aircraft, and it could provide a new direction of energy harvesting system in aviation field.
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    High energy and high intensity electron and X-ray beams by pyroelectric effect
    (Cranfield University, 2012-07) Hockley, Matthew; Huang, Zhaorong
    The production of x-rays has been a useful technique in many areas of science, medicine and various industries for over 100 years. Over this time various new methods of generating x-rays have been produced, allowing improved performance in existing applications as well as the application of x-rays in new areas. In this project a novel method of electron beam production, with the potential for development into a novel method of x-ray production is presented, using both pyroelectric and ferroelectric materials. The pyroelectric e ect, i.e. the generation of a charge due to a change in temperature is an e ect exhibited by certain dielectric materials. This e ect has previously been used in x-ray generation, and has been su ently successful that a commercial device has been produced: the Amptek Cool-X. While the Cool-X has only a limited electron / x-ray energy, high energy applications of this technology are present in the literature. This shows that these materials are capable of high voltages. However, the technique is not suitable for high beam intensity applications, limiting the potential use of pyroelectric x-ray devices. Ferroelectric electron emission is a technique used to generate elec- tron beams by applying a high voltage pulse to a specially prepared cathode. This technique has shown great potential for very high intensity pulsed electron beam generation. The major drawback of this technique is that while the cathodes are relitivly cheap and easy to produce, the other required equipment (such as high vacuum systems and high voltage pulse generators) is typically large and expensive. This project combines these two technologies to create an electron beam generation system that exhibits many of the ad- vantages of each technology, while minimizing the drawbacks. The result is a device using pyroelectric materials as voltage generatingelements for electron acceleration and high voltage pulse production, while a ferroelectric cathode is employed as the electron generating element. This system has been shown to, depending on con guation, be capable of accelerating voltages above 5 kV, and generating total collected charges of more than -40 nC per pulse.
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    Impedance measurements for determination of elastic and piezoelectric coefficients of films
    (Maney Publishing, 2010-03-31T00:00:00Z) Pardo, L.; Jiménez, R.; García, A.; Brebøl, K.; Leighton, Glenn J. T.; Huang, Zhaorong
    Most of those techniques used for the measurement of elastic coefficients for bulk piezoelectric ceramics are not applicable to films deposited on thick substrates because the measured properties, such as the resonant frequency, are usually dominated by the presence of the thick substrate. This work presents a preliminary study for the application of the automatic iterative method of Alemany et al. for the determination, from complex impedance measurements, of the film properties using a conventional self‐supported cantilever design used in microelectromechanical system applications and fabricated from a PZT thick film on a Si based substrat
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    In process temperature monitoring of energy beam processing.
    (Cranfield University, 2019-07) Frumosu, Lydia; Huang, Zhaorong; Giusca, Claudiu
    The use of non-thermal and atmospheric plasma has been growing in recent years. Applications in wound sterilisation, food decontamination, cleaning and the more traditional machining and deposition are just some of the areas in which new technology is being developed. With the growing use of cool plasma comes the requirement to test and understand the temperature distribution of the jets. Current methods into temperature measurement revolve around spectroscopy and other non-contact methods. Spectroscopy can pose a challenge as a measurement device as it lacks the ability to measure overall gas temperatures in non-thermal plasmas. Contact measurement thermometers, such as thermocouples and resistance temperature detectors are an alternative which can provide an insight into the temperature of the ions and neutral species. However these sensors pose a challenge in gaining accurate or precise temperature measurements due to their susceptibility of electromagnetic interference. Fibre Bragg grating sensors have the ability of measuring both temperature and strain without electromagnetic interference. They possess the ability of multiplexing, being able to measure multiple temperatures across a single fibre, which can aid in measuring over a long distance. They also have the added benefit of being small, lightweight and have quick thermal response times. Additionally their small heat capacity reduces the effect on the temperature of the measurand, improving their accuracy over other physical probes. In this experiment fibre Bragg grating sensors 600 μm and 1000 μm in length and 10μm in diameter have been used to characterise the temperature distribution of non- thermal microwave plasma and thermal radio frequency plasma jets. Thermocouples have been used to compare results against current technologies. Results show the fibre Bragg grating sensors have been successful in determining plasma temperature changes over time, distance and across a variety of different parameters.
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    In-situ tuning of catalytic activity by thermoelectric effect
    (2017-05) Achour, Abdenour; Huang, Zhaorong
    For the first time, a new type of reactor which can combine thermoelectric energy harvesting and electrochemical promotion of catalysis was developed. A novel use of thermoelectric material as a catalyst support and promoter was investigated. A facile, cost-effective and scalable synthesis of thermoelectric material BiCuSeO has been developed. It was discovered that the catalytic activity of Pt supported on the thermoelectric material BiCuSeO, through the ethylene oxidation, can be increased by several tens to several hundreds of times by a thermoelectric voltage. We call this Thermoelectric Promotion of Catalysis (TEPOC). The catalytic activity under fuel-lean and fuel-rich conditions was also investigated for ethylene oxidation. It is believed that oxygen was more strongly and C₂H₄ was weakly adsorbed on the catalyst Pt surface under lean-fuel conditions (O₂/C₂H₄ > 1). However, under rich-fuel conditions (C₂H₄/O₂> 1.4), C₂H₄ became strongly adsorbed (probably chemisorbed) to the surface especially at a high Seebeck voltage, this blocked the catalyst surface, reduced the catalytic active site, hence the rate became smaller. To further investigate the TEPOC effect, the CO₂ hydrogenation over the same catalysts supported on the thermoelectric BiCuSeO was also studied and the results confirmed similar significant promotional effect. It also was found that a negative thermoelectric voltage shifted chemical equilibrium towards the reverse water gas shift (RWGS) reaction and CO selectivity. As a results, the CO₂ hydrogenation conversion reached 48.4% (CO₂:H₂ = 1:4) with 100% CO selectivity for Pt(80)/BCSO at 656 K, which was above the thermodynamic equilibrium conversion (TEC) under no Seebeck voltage without methanation. It was established a linear relationship between Ln(r) and –eV/kьT, where –eV/kьT is the ratio between the extra electrochemical energy induced by thermoelectric effect and the thermal energy of an electron. From this it was derived that the promotional effect was attributed to the change of work function of the catalyst surface, accompanied by charge transfer from the bulk to the surface due to the thermoelectric effect. ii The discovery of TEPOC prompts that many catalytic chemical reactions can be tuned in-situ and independently from the change of conditions within the reaction chamber, to achieve much higher reaction rate, or at lower temperature, or have better desired selectivity through changing the backside temperature of the thermoelectric catalyst support.
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    In-situ tuning of catalytic activity by thermoelectric effect for ethylene oxidation
    (American Chemical Society, 2018-09-20) Achour, Abdenour; Liu, Jian; Peng, Ping; Shaw, Christopher; Huang, Zhaorong
    Thermoelectric material BiCuSeO used as a support and promoter for catalytic ethylene oxidation is reported here. The catalytic activity on the continuous and non-continuous catalyst Pt supported on BiCuSeO was observed to be promoted in-situ by a thermoelectric Seebeck voltage generated by the temperature gradient across the material. It is also shown this thermoelectric promotion of catalysis enabled the thermoelectric material BiCuSeO itself to be highly catalytic active for ethylene oxidation. A good linear relationship between the logarithm of the reaction rate and the thermoelectric Seebeck voltage was observed. This thermoelectric promotion of catalysis is attributed to the change of work function of the catalyst surface, accompanied by a charge transfer from the bulk to the surface due to the thermoelectric effect.