Shien-Ping Feng is an Associate Professor in the department of Mechanical Engineering at Hong Kong University. He received his Ph.D. in chemical engineering from National Tsing-Hua University (2003-2008), and was a postdoctoral associate at MIT (2009-2011) prior to his appointment at Hong Kong University. He was a principal engineer, section manager and technical manager at Taiwan Semiconductor Manufacturing Company (2001-2008), and a deputy director at Tripod Research Center (2008-2009). His current research is focused on electrochemical processing and interfacial characterization of nanostructured materials, and their applications on energy conversion and storage.
Direct Thermal Charging Cell for Low-Grade-Heat-to-Electricity Conversion
Low-grade thermal energy is abundantly available in the form of waste heat or in the environment.1, 2 Current technologies using liquid-based thermo-electrochemical cells (TECs) is both cost-effective and scalable for low-grade heat harvesting, and their temperature coefficient (mV/K) is one order of magnitude higher than that of solid-state thermoelectrics.3, 4, 5 The research on TECs has mainly focused on the exploit of thermal gradient or thermal cycle, but the potential of these approaches has been limited by the poor energy conversion efficiency or the need of external electricity. We invent a new direct thermal charging cell (DTCC) for low-grade-heat-to-electricity conversion under an isothermal condition without the aid of the thermal gradient across two electrodes or the thermal cycle.6 The DTCC consists of graphene oxide (GO)/platinum nanoparticles (PtNPs) cathode and polyaniline (PANI) anode and an aqueous Fe2+/Fe3+ electrolyte, which can be thermally charged in the open circuit condition. Under isothermal operation, the pouch cell configuration of DTCC with a short distance between two electrodes can be employed for improving electrolyte conductance and rapid heating. Notably, the thermal voltage is generated based on thermo-pseudocapacitive reaction at the GO-electrolyte interface, demonstrating a very high temperature coefficient of 5.0 mV/K and the DTCC exhibits the energy conversion efficiency of 5.19% at 70oC (39.6% of Carnot efficiency). The great applicability of this new thermo-electrochemical system has been demostrated on supplying power for an electrochromic smart window by immerimg DTCCs in a hot water and lightening up an organic light emitting diode by placing DTCCs on a running compressor.
Assoc. Prof. Dr Azlin Fazlina Osman obtained her PhD degree in Nanotechnology from Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queenland, Australia. She is now a senior lecturer at School of Materials Engineering, Universiti Malaysia Perlis and a Leader for Nanotechnology Group in Center of Excellence Geopolymer and Green Technology (CEGeoGTech), Universiti Malaysia Perlis. Her research interests are in the field of biomedical polymer, nanotechnology, nanocomposites, biocomposites and structure-property relationships of materials. She is the first author / corresponding author of several articles published in Q1 and Q2 journals, and has published more than 70 scientific papers in the field of polymer, composites, nanocomposites, nanoparticles, biocomposites, geopolymer and biomedical polymers. She is supervising several postgraduates who are working in these particular areas.
Copolymer-Based Nanocomposite and Its Potential for Biomedical Applications
Copolymer is defined as polymer that produced from two or more different monomers combined together through copolymerization process. The combination of copolymer and nanofiller materials will produce the copolymer based nanocomposites . The copolymer generally has combination properties of the two monomers used to form it. These properties are useful to meet certain targeted properties requirement, therefore the use of copolymer other than homopolymer can provide greater prospect for broader applications. As opposed to the homopolymer matrix, the use of copolymer type matrix to form nanocomposite is rare, due to the complexity of the resultant ‘copolymer nanocomposite’ structure that require further study and understanding on structure-processing-properties aspect. However, our recent studies proved that the poly(ethylene-co-vinyl acetate) copolymer based nanocomposites are more promising for biomedical applications such as for encapsulant of implantable device due to the combination of biocompatibility, flexibility and toughness properties [40, 62]. The addition of low nanofiller loading can give the positive impact to the host copolymer behaviour due to the large surface area of nanofiller which allows a good matrix-nanofiller interaction. In order to obtain an optimized copolymer nanocomposite, the correct processing route to exfoliate the nano-montmorillonite was identified to ensure good dispersion of this nanofiller in the copolymer matrix. We have proved that improvement in tensile, toughness, fatigue, thermal and thermomechanical properties can be obtained when the well-engineered nano-montmorillonite was employed as nanofiller in the poly(ethylene-co-vinyl acetate) nanocomposite. Without the use of expensive and toxic chemicals, it can be adopted as a new nanotechnology approach for biomedical applications.