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Akira SUZUKI

Cross-Coupling Reactions of Organoboranes: An Easy Way for Carbon-Carbon Bonding

Reactions in which new carbon-carbon bonds are formed are key steps in building the complex, bio-active molecules such as medicines and agrochemicals. They are also vital in developing the new generation of ingeniously-designed organic materials with novel electronic, optical or mechanical properties, likely to play a significant role in the burgeoning area of nanotechnology. The palladium-catalyzed cross-coupling reaction between organoboranes and organic halides in the presence of base was first developed about 40 years ago. It offers a powerful and general methodology for forming carbon-carbon bonds. The scope of the reaction has continued to evolve and broaden modern synthetic requirements. The reaction has proved to be extremely versatile. It was first carried out between alkenyl reactants but over the years, it has extended the range to couple carbons in aryl, alkyl and alkynyl groups under a wide variety of conditions.

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Jong-Heun Lee

Sensitive, selective, and reliable oxide semiconductor gas sensors: New opportunities and challenges

Gas sensors have been widely used to detect harmful, explosive, and toxic gases because of their high sensitivity, simple structure, small size, and cost effectiveness, which will be more intensively employed in environmental monitoring, artificial olfaction and medical diagnosis from exhaled breath. In particular, oxide semiconductor chemiresistors and their array can be integrated within smart phones and portable devices and will be connected to other devices/systems through Internet of Things and wireless communication. To date, various nanostructures with high surface area to volume ratio, such as nanoparticles, nanowires, nanosheets have been explored to enhance the gas response. However, for demand-based design of high performance gas sensors, many issues still remain unsolved, which include the detection of ultralow concentration of analyte gas, highly selective detection of a specific gas, moisture- independent gas sensing, and the establishment of sensing library toward diverse analyte gases for artificial olfaction. In this presentation, various new and general strategies for sensitive, selective, and reliable gas sensing will be suggested, which are the use of hollow and hierarchical nanostructures with high gas accessibility, p-type oxide semiconductors with high catalytic activity, micro-reactors to promote the gas reforming reaction, bilayer sensing film consisting of catalytic overlayer, and hetero-nanostructures as sensing materials or platforms.

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Peidong Yang

Diamond: a Brilliant Wide Bandgap Semiconductor

Solar-to-chemical (STC) production using a fully integrated system is an attractive goal, but to-date there has yet to be a system that can demonstrate the required efficiency, durability, or be manufactured at a reasonable cost. One can learn a great deal from the natural photosynthesis where the conversion of carbon dioxide and water to carbohydrates is routinely carried out at a highly coordinated system level. There are several key features worth mentioning in these systems: spatial and directional arrangement of the light-harvesting components, charge separation and transport, as well as the desired chemical conversion at catalytic sites in compartmentalized spaces. In order to design an efficient artificial photosynthetic materials system, at the level of the individual components: better catalysts need to be developed, new light-absorbing semiconductor materials will need to be discovered, architectures will need to be designed for effective capture and conversion of sunlight, and more importantly, processes need to be developed for the efficient coupling and integration of the components into a complete artificial photosynthetic system. In this talk I will begin by discussing the challenges associated with fixing CO₂ through traditional chemical catalytic means, contrasted with the advantages and strategies that biology employs through enzymatic catalysts to produce more complex molecules at higher selectivity and efficiency. I then discuss a number of different photosynthetic biohybrid systems (PBS) architectures from the last few years, and the numerous strategies to interface biotic and abiotic components. Each demonstrates the advantages of PBSs in converting sunlight, H₂O and CO₂ into food, fuels, pharmaceuticals, and materials. Finally, I will outline the future of this field, opportunities for improvement, and its role in sustainable living here on Earth, and beyond.

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Akira Fujishima

TiO₂ Photocatalysis to Contribute Comfortable Atmosphere

The tremendous amount of research that has been carried out in the two closely related fields of semiconductor photoelectrochemistry and photocatalysis during the past three decades continues to provide fundamental insights and practical applications. The principles and measurements obtained TiO₂ with photoelectrochemical studies have led to the research activity on heterogeneous photocatalysis, where the strong photooxidative activity of TiO₂ has been applied to environmental cleanup. This resulted in the concept of “light cleaning”, i.e., deodorizing, disinfection, and decontamination of air, water and surface with TiO₂thin films and light. Also we reported the novel photo-induced superhydrophilicity of TiO₂ and proposed the concept of self-cleaning superhydrophilic properties of TiO₂. Now in the world, there are potential applications of photocatalysts in various fields. Our research focuses on developing transparent anti-fogging coatings for the walls of buildings and glass for the purpose of self-cleaning and to develop efficient photocatalytic materials to purify environmental air and water. We believe that the purification of water and air is an extremely important area in the research. I will report present situation of phototcatalysis field.

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Antony Bourdillon

Geometric space - The extension of extremely dense unit cells

Geometric space has extraordinary properties; foremost is coherence [1] with plane waves in linear Cartesian space. As Einstein’s curved space is locally Euclidean; dense space is locally icosahedral, and geometric in extension. Geometric space can be found in Fractals; in Quasicrystals; and in any place where quantities are measured in spatially geometric series.
The Quasicrystal is a relatively new kind of solid, intermediate between crystals and compound glasses. It has many peculiar properties including non-Drude conductivity; geometric electronic band structures; peculiar mechanical and magnetic effects etc. The solid is logarithmically periodic. Mathematicians have thought to explain it by inventing dimensions, but as an ancient European maxim has it, “Beings should not be multiplied without necessity” – so also dimensions. In 3D geometric space the mathematics are simple and data inescapable, while various physical models describe the quasicrystals.
The facts suggest enhancements for Finite Element Analysis undertaken in a new matrix, with known metric, with a new physical law, and a new unit cell having 12 icosahedral nodes.

[1] Diffraction line width in quasicrystals – sharper than crystals, A.J. Bourdillon, Journal of Modern Physics, 7, 1558-1567 (2016)
DOI: 10.4236/jmp.2016.712142
https://www.youtube.com/watch?v=eVzH1CkPK9E     Geometric space and quasicrystals

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Sang Il Seok

Inorganic-Organic Hybrid Perovskite Materials: Focusing on Solar Cells

Perovskite materials occupy a very important position in the functional materials, which exhibit many excellent properties including ferroelectricity piezoelectric, thermoelectric, antiferromagnetic, giant magnetoresistance, insulation, semiconductor, conduction, and even superconductivity. They are represented by the general formula ABX3 and have the same crystal structure as calcium titanate (CaTiO₃), where A and B sites accept inorganic cations of various valency and ionic radius, and X site accommodates anions (halogen or oxygen). Inorganic-organic hybrid halide perovskite materials using suitable organic species as the A cation and halides as X anion have attracted much attention recently due to the very high efficiencies recorded in photovoltaic. The hybrid materials exhibit beneficial properties for high-performance photovoltaic systems such as a suitable band gap (1.5 - 1.4 eV), high absorption coefficient (10⁴ - 10⁵ cm^-1), low exciton binding energy (< 50 meV), and long charge-carrier diffusion length (~175 µm). Based on above distinct properties of hybrid perovskite materials, we have been able to fabricate stable, highly efficient perovskite solar cells through the engineering of cell architectures, perovskite compositions, deposition processes, and defects, and new charge transport materials. This presentation introduces the results of the study.

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Robert J. Nemanich

Diamond: a Brilliant Wide Bandgap Semiconductor

Diamond is a semiconductor with extreme and unique properties which enable applications for high power and high frequency electronics, radiation detectors, electron emitters for ultra high voltage vacuum switches and traveling wave tube cathodes, and thermionic emitters for energy conversion. Diamond as a wide bandgap semiconductor shows outstanding electronic properties and the highest known thermal conductivity. Its unique properties include excellent electron emissivity from hydrogen terminated surfaces, room temperature UV exciton emission and optical defect centers (N-V and Si-V) that have been considered for quantum communication.

Results have shown high voltage p-i-n diodes which display efficient electron emission appropriate for high voltage vacuum switches. Lateral MOSFET devices with ALD dielectrics have sustained a stable two dimensional hole-gas with sheet charge densities greater than 1 x 10M¹³ cm^-2. Diamond surfaces have shown record low work functions and demonstrated thermionic energy conversion.

The tremendous progress in diamond applications is now limited by materials challenges: reducing defect and impurity densities in substrates and epitaxial layers, understanding and limiting dopant compensation, preparing stable dielectric interfaces, preparing low resistance contacts, and heterostructure formation for high mobility devices and III-V integration. As research progresses on all of these topics, new device concepts will be developed based on the outstanding, extreme and unique properties of diamond materials.

Acknowledgement: financial support by ARPA-E, MIT-Lincoln Laboratory, NASA, the National Science Foundation, the Office of Naval Research.