Biography:

Masaru Matsuo has completed his PhD at Kyoto University in Japan and he was a professor of Nara Women’s University. After his retirement, he became a full time professor of Dalian University of Technology in China. Since September 1^st 2014, he is a visiting professor of Dalian University of Technology. He has published more than 200 papers in refereed journal articles. He is IUPAC fellow and “Certificate of Membership Award of ACS (July 2015~ July 2018). He received “Award of Society of Fiber Science and Technology of Japan on May 1990, “Paul Flory Polymer Research Prize” on April 2010 and “Certificate of friendship Award of Liaoning Province in China” on September 2011.

Abstract:

Superparamagnetism particles have been applied to magnetic fluids, microwave absorption materials, drug delivery systems and pigments. The high magnetization under external applied magnetic field could be obtained by using Zn-doped Fe₃O₄ nanoparticles. By the replacement of Fe³⁺ ions by Zn²⁺ ions in A-site of Fe₃O₄ crystal unit with inverse-spinel ferrite, the super-exchange interaction between spins of Fe³⁺ existing in A-site and B-site becomes weakened, while the double-exchange interaction between Fe³⁺ and Fe²⁺ in B-site remains. This indicates that the magnetization increases with Zn doping. Different from the general concept, however, the highest magnitude was x = 0.2, when Zn-doped Fe₃O₄ is represented as Zn_xFe_3-xO₄ (0x1). To investigate such contradiction, the crystallinity and crystal size of Fe₃O₄ by the doping were evaluated using X-ray and dielectric measurements. The crystallinity and crystal size decreased with increasing x up to 0.4 but they increased beyond 0.5 inversely. This indicated that Fe₃O₄ crystal can not accept further doping by Zn²⁺ to maintain Zn_xFe_3-xO₄ crystal. This is due to the fact that Zn doping resulted in the damage of the Fe₃O₄ crystal, since the atomic size (74 pm) of Zn²⁺ is bigger than that of Fe³⁺ (64 pm). As for Mg doping represented as Mg_xFe_3-xO₄, Fe₃O₄ crystal accepted Mg²⁺ up to x = 1 because of similar size of Mg²⁺ (65 pm). In this case, Fe³⁺ ion in A-site becomes zero and crystal structure of Fe₃O₄ crystal was collapsed. The crystallinity and crystal size were sensitive to their dielectric properties. The complex impedance for Mg_0.6Fe_2.4O₄ and MgFe₂O₄ with no crystal domain can be represented by Kramers-Kronig relation which has been utilized for amorphous materials, while that for Fe₃O₄ and Zn_0.2Fe_2.8O₄ can be represented by  the equivalent circuit model with three units relating to suppressed circle by Cole-Cole plots. The three units correspond to particle (grain) resistance, grain boundary resistance and interface resistance between electrode and grains indicating the existence of crystal particles. The dielectric behaviors of superparamagnetism particles were in good agreement with X-ray diffraction profiles. The DC component of conductivity was highest for Zn_0.2Fe_2.8O₄ with the highest magnetization.

Biography:

Jae-Jin Shim received his BS degree from Seoul National University in 1980, MS degree from KAIST in 1982, PhD degree from the University of Texas at Austin in 1990. He has been a professor in Yeungnam University since 1994 and served as School Chairman and Vice-Dean of Engineering. He served as the President of the Korean Society of Clean Technology and Vice President of the Korean Society of Engineering Education. He is the Directors of the Institute of Clean Technology and the Clean Energy Priority Research Center. He has published more than 150 papers in reputed journals and served as the Chief Editor of “Clean Technology”. His current research interests are synthesis and applications of graphene (or carbon nanotube)-based nanomaterials for supercapacitors, catalysts, and sensors; syntheses of polymers and organic materials using supercritical fluids and ionic liquids; living polymerization in supercritical fluids and ionic liquids; and clean technology.

 

Abstract:

Electrical double layer capacitors (EDLC) such as activated carbon have high power densities but do not have high energy densities, which hurdles the use of supercapacitors in many commercial sectors. To overcome this problem, many researchers have been working to improve the energy density of supercapacitors. Metal oxides or sulfides have been employed to exploit their pseudocapacitive natures in energy storage (supercapacitor) and photocatalyst applications. They have shown good electrochemical performances, but have not been satisfactory. Various materials such as graphene and carbon nanotubes have studied to enhance the electrochemical properties owing to their large surface area and high electrical conductivity. Synergistic effects of excellent conductivities of graphene and high electrical properties of metal oxides or polymers have improved the overall electrochemical performances tremendously.

In this study, graphene, graphene oxide, and reduced graphene oxide have been tested for improving performances as supercapacitors and photocatalysts. Other methods have also been used such as doping of graphene with nitrogen or sulfur, using metal sulfides instead of metal oxides, and using highly porous materials as substrates. In the synthesis of these materials, a cleaner technology has been employed.

 

Biography:

Lavinia BALAN obtained the PhD degree from the University Henry Poincaré in Nancy, France, in 2005. Her PhD was devoted to the elaboration of an original material for the anode of Li-ion batteries. After a post doctorate in Orleans and then in Mulhouse, she joined the Department of Photochemistry (DPG) of Mulhouse in 2006 as a CNRS Senior Researcher. She opened a new field of research in this laboratory, viz. the photoassisted synthesis of metal nanoparticles and metal-polymer nanocomposite materials. Since December 2009, L. Balan joined the Institute of Materials Science of Mulhouse (IS2M) CNRS-UMR 7361. She has published more than 100 papers, 4 book chapters and held 5 EU patents. Her lines of research are concerned with (photo)chemical synthesis of metal/polymer nanocomposites and design, customization and characterization of metal nanoparticles and nanocrystals (quantum dots) suited for advanced applications in the fields of optic, photonics, plasmonics, information storage, imaging or biology. Dr. L. Balan has been serving as an editorial board member for few scientific journals.

 

Abstract:

The size dependent properties of noble metal nanoparticles (MNPs) have created a great promise for their use in a variety of optical, electronic and biomedical applications. Nowadays, a great diversity of techniques and methods were developed for their synthesis: chemical, thermal, photochemical or biological. Among them, photochemical approach has proven an excellent tool to synthesis nanoparticles and also nanocomposites materials as well in the investigation of the mechanistic aspects of their formation. In particular, present the advantages of a “green” and “highly flexible” character and a strong control in both spatial and temporal directions. In this context, firstly, we will use the photochemistry to generate MNPs through photo reduction of a metal precursor using free radicals generated from photosensitizers in an aqueous solution or directly generated onto a glass surfaces in order to produce plasmonic surfaces. Thus efficient nanoparticles synthesis and their morphological control require a careful selection of experimental conditions such as photonic and chemical parameters. Moreover, the photochemical tool was used not only to the nanoparticles synthesis but also to obtain advance nanomaterials as nanocomposites metal/polymer. The hybrid nanocomposites have been obtained by combing the in situ photoreduction of MNPs with the acrylates monomers photopolymerisation. Specific interactions between the macromolecular network and the nascent particles was funded to play an important role insofar as they control the access of metal atoms to the different crystalline planes of the growing nanoparticles, which is necessary to obtain anisotropic objects. The assembling process of MNPs in the polymer matrix was the next step of our work. Controlling both the synthesis and multi-scale organization (nano, micro and macro) of such cross-linked organic-inorganic nanomaterial opens promising prospects in the field of advanced materials.

Biography:

Jau Tang is a distinguished professor in the Institute of Technological Sciences at Wuhan University in China. His research areas include nanoscience, 4D electron microscopy, ultrafast phenomena, single-molecule spectroscopy, phase transitions, plasma hydrodynamics, optoelectronics, synthetic diamond growth, photochemistry and electron transfer reactions. He received his PH.D. degree from UC Berkeley (1981), and has worked at Argonne National Lab, Bell Labs, Caltech prior to Wuhan University. 

 

Abstract:

By combining high spatial and temporal resolution of 4D electron microscopy we have demonstrated its some applications in nanoscience and nanotechnology. We are able to investigate ultrafast dynamics and atomic scale spatial resolution of nanomaterials which might help soling important issues in energy, environment and health related issues in modern society.  In our 2015 Science paper we have used USEM (ultrafast scanning fast electron microscopy) ultrafast dynamics of photo-induced electrons and holes induced by fs laser in p-n semiconductor junctions.  We have observed ballistic dynamics and gating mechanism of the depletion zone for the hot charged carriers at short times, rather than the more familiar carrier diffusion. Moreover, we have also observed THz plasma waves at high laser fluence due to Coulomb forces among carriers.  In our another Science paper in 2017 and a paper in Science Advances we have studied photo-induced rotational and translational motion of single gold nanoparticles Using UTEM (ultrafast transmission electron microscopy) we observed ballistic motion with friction, yet at longer time scales abnormal diffusion with extremely fast diffusion was observed.  We have identified steam nanobubbles generated on the laser-heated gold nanoparticles are the driving force for such fast dynamics. We have also investigated the processes of nucleation from the liquid phase to final crystallization of TiO₂ nanoparticles to elucidate the mechanism. Eutectic reactions of alloys from GaAs nanowires encapped by a gold tip were also studied to improve understanding of the lase heating and heat transfer processes during superstructure formation of the alloy.   In another work of USEM of graphene monolayer, we have observed dynamic spatial and temporal distributions of charged carrier, exhibiting a crater-shaped charge density map at high fluence and yet a Gaussian distribution at low fluence. We have attributed these phenomena to Auger-assisted charge recombination processes.