Conference Programme

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Overview
Session
L-02: Symp L
Time:
Monday, 19/Jun/2017:
4:00pm - 6:15pm

Session Chair: Ajayan Vinu, UNIVERSITY OF SOUTH AUSTRALIA
Location: Rm 309

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Presentations
4:00pm - 4:30pm
Keynote

Supercritical Route for Nano Materials -Catalyst, Hybrid Materials and Nano Ink-

Tadafumi ADSCHIRI

WPI Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Japan

Supercritical water provides a homogeneous phase for water-organic systems, which is a key to synthesize organic modified nanoparticles (NPs) with high concentration. The surface control of NPs leads to change the morphology of NPs, namely the exposed surface. The (100) surface of cerium oxide was expected to be most reactive face, but it had been considered difficult to synthesize 100 face exposed cerium oxide NPs, because this surface is the most unstable. However, the supercritical method could solve the problem by the in-situ capping of the most reactive face with organic molecules. It is demonstrated that this catalyst can be used for many applications, including low temperature waste heat recovery with endothermic reaction (bitumen/black liquor conversion), methane coupling etc. The surface control of NPs is also a key to make nano composite materials with polymers or nano ink. Supercritical method can be used to make a nano ink for 3D-printing. By tuning the surface modifier for YSZ nanoparticles, viscosity and surface tension of the ink was optimized for ink jet printing, and thus the artificial tooth was fabricated. The method was used to make a 3D Li ion battery structure, as well.


4:30pm - 5:00pm
Invited

Metal Oxide Nanosurfaces and Hetero-interfaces for Solar Harvesting Applications

Sanjay MATHUR, Yakup GÖNÜLLÜ, Thomas FISCHER

University of Cologne, Germany

Metal oxide nanostructures with hetero-contacts and phase boundaries offer unique platform for designing materials architectures for solar harvesting applications. Besides the size and surface effects, the modulation of electronic behavior due to junction properties leads to modify surface states that promote higher efficiency. The growing possibilities of engineering nanostructures in various compositions (pure, doped, composites, heterostructures) and forms (particles, tubes, wires, films) has intensified the research on the integration of different functional material units in a single architecture to obtain new materials for solar energy harvesting application. However, metal oxide nanostructures need a conductive substrate for electron transfer. Moreover, the substrate should be transparent in order to harvest more light. Therefore, flexible devices transparent conductive electrodes from wet processed metal nanowire or nanofibre networks became a promising alternative to high vacuum deposited brittle ITO or FTO layers.

In this work we present the deposition and modification of semiconducting metal oxides and their multilayers (TiO2, Fe2O3 and TiO2/Fe2O3) for photoelectrochemical (PEC) hydrogen production. The deposition parameters for thin film creation were optimized with respect to the PEC performance of the resulting materials in both alkali solution and simulated seawater. The long-term performances of the metal oxide photoanodes were determined in alkali and seawater electrolyte, as well. The results presented that the multilayered TiO2/Fe2O3 photonanode yielded higher photocurrent density (1.8 mAcm-2 at 1.23 V) with very stable conditions even after 1-week measurement. Moreover, a TCM from silver nanowires with a diameter of 80 nm and a lenght of 5 µm (aspect ratio of 62.5) were suggested as alternative substrate.


5:00pm - 5:30pm
Invited

Soft Processing for Nano Carbons: Direct Fabrication of Functionalized Graphenes and Their Hybrids Inks via Submerged Liquid Plasma [SLP] and Electrochemical Exfoliation [ECE] under Ambient Conditions

Masahiro YOSHIMURA, Jaganathan SENTHILNATHAN, Kodepelly Sanjeeva RAO

National Cheng Kung University, Taiwan

Nano-carbons like Grapnenes have greatly been interested in various fields of researches,where the large scale synthesis of nano-carbon should be free from using excess energies for firing, sintering, melting,vaporizing and/or expensive equipments. We, propose here Soft processing of functionalized Graphenes at ambient conditions. The Soft processing provides number of advantages which includes (a) simple reaction set up,(b) at ambient conditions, (c) simple procedure and (d)less operating costs and wastes.

In the present study, we have utilized “Submerged Liquid Plasma [SLP]” and “Electrocemical Exfoliation[ECE] methods. SLP methods resulted the direct synthesis of Nitrogen functionalized Graphene Nano-sheets from Graphene suspension and/or Graphite electrode in acetonitrile liquids.[1,2] Products contains few layers (< 5) Graphene nanosheets. Unsaturated or high energy functional group (e.g. C=C, C=N and C≡N) have formed in the products. We could confirm those functionalized Graphenes are electrochemically active. Using pencil rods instead of Graphite rods we have also succeeded to prepare the Nano-clay/Graphene hybrids by this SLP methods [3]. Reduction and functionalization of Graphene oxides [2] and Synthesis of Graphene/Au Hybrids [4] also realized by SLP.

In the ECE, graphite anode is exfoliated electrochemically by H2O2-NaOH[5,6] or Glycine-H2SO4[7] aqueous solutions under ambient temperature and pressure,for 5-30 min with +1-+5 volt, into 3-6 layers Graphene Nanosheets[GNs]. Those conditions are much milder than those reported before using other chemicals like ionic liquids and/or H2SO4-KMnO4,etc.,because O22- ions or ionic complex like Glycine-HSO4- would assist the exfoliation of graphite layers. Our products:GNs suspended in solutions can be transformed in the 2nd step in the same container using BrCH2CN/dioxane into N-FG, further into Au-Hybridized N-FG by the sonification with Au nanoparticles. We have confirmed the excellent catalytic performance of those hybrids[5,6] It should be noted that Soft Processing can directly produce “Graphene Ink”;Graphenes dispersed in various liquids, under mild conditions.

References:

[1] J. Mater Chem A, (2014)2, 3332

[2] Scientific Reports, 4(2014), 04395

[3] Carbon, 78(2014), 446

[4] J. Mater Chem A, 2015, 3,3035-3043

[5] Sci. Rep. 4 ,4237 (2014)

[6] Nanoscale (2014) 6,12758

[7] Adv. Funct. Mater. 2015, 25, 298-305


5:30pm - 5:45pm
Oral

Experimental Investigation of the Distribution of Energy Deposited by FIB in Ion-Beam Lithography

Nazim GUSSEINOV1, Maratbek GABDULLIN1, Yana SHABELNIKOVA2, Sergey I. ZAITSEV2

1Al-Farabi Kazakh National University, Kazakhstan; 2Institute of Microelectronics Technology RAS, Russian Federation

Ion beam lithography (IBL)is very similar to electron beam lithography (EBL), but uses much heavier charged particles, ions. Spatial (transverse) resolution of electron lithography is fundamentally restricted by free path of secondary electrons, which is within range of 10nm. In comparison to electrons ions move in straighter paths than electrons, secondary particles (atoms) have very short ranges because of a lower speed of the ions. This suggests that ion-beam lithography can overcome the fundamental physical resolution limit of electron beam lithography (10nm). But for various reasons, at present IBL is insignificant in comparison to the position of the EBL.

In the report at the beginning the undoubted advantages of ion-beam lithography in comparison to electron-beam lithography are listed and as consequence a task of the study of basic laws of ion interaction with resists is formulated. Two important results will be reported. First, rigorous comparison of sensitivity of the resist (PMMA) to irradiation by electron and ion beams was conducted. It is shown that as in the case of an electron exposure the resist demonstrates both a positive (at low doses) and negative (at higher doses) behavior. It turned the sensitivity of the resist is approximately a thousand times and two thousand times higher in positive and in the negative regions correspondently. The second series of the experimental study was concerned to investigation of etching depth of the resist depending on the radiation time. It was found that, in contrast to electron exposure, the distribution of energy deposited is strongly inhomogeneous in depth, which results to strongly inhomogeneous etching rate as function of the depth and the radiation dose. The data were compared with simulated ion energy losses distribution and after fitting such important parameters as ion energy range (~20nm) and resist contrast (~3.1) were restored for the first time.


5:45pm - 6:00pm
Oral

Low-Temperature Chemical Transformations for High-Performance Solution-Processed Oxide Transistors

Rohit Abraham JOHN1, Nguyen Anh CHIEN1, Nripan MATHEWS1,2

1School of Materials Science and Engineering, Nanyang Technological University, Singapore; 2Energy Research Institute@NTU (ERI@N), Nanyang Technological University, Singapore

The challenges associated with low temperature solution processed metal oxide network formation has hindered the realization of high performance solution based electronic circuitry at temperatures lower than 200oC. Here, UV irradiation is embarked upon as a route to effectively transform the chemical precursors to semiconducting metal oxides with high electrical quality. High performance UV irradiated Indium Oxide (In2O3) and Indium Zinc Oxide (IZO) thin film transistors with mobility greater than 30cm2/Vs are demonstrated from nitrate based precursors. The chemical transformation is monitored by detailed spectroscopic studies, physical characterization and temperature dependent electrical transport measurements. In comparison to thermal annealing, UV annealing seems to result in higher M-O-M network formation (depicted by M-O bonds in XPS), better removal of chemical impurities (depicted by FTIR and XPS), and structural relaxation driven electron doping transforming the oxygen vacancies to act as shallow donors (depicted by TFT characteristics, XPS, XRD and Urbach studies). Our results provide new insight into how UV irradiation drives metal oxide network formation and passivates the subgap density of states (DOS).


6:00pm - 6:15pm
Oral

Structure of Gold-Silver Core-Shell Structured Colloids

Ian J. GODFREY1,2, Ivan P. PARKIN1, Shinya MAENOSONO2, Gopinathan SANKAR1

1University College London, United Kingdom; 2Japan Advanced Institute of Science and Technology, Japan

Solution-phase nanoparticle preparation methods often produce colloids – these materials pose unique characterisation challenges due to their dilute concentrations, small particle sizes and the need to remove the supernatant for many techniques. Colloidal nanoparticles are of interest for their inherent catalytic properties and potential for deposition on supports to form heterogeneous catalysts. The catalytic properties of gold, silver and gold-silver nanoparticles and colloids have been widely studied, along with combinations of gold and other common catalytic metals. Recent research has found that the catalytic properties of gold-silver nanoparticles (core-shell, alloy) are structure dependant.

In the gold-silver system, the similarity of the crystal structures additionally hinders diffraction-based techniques. XAFS (x-ray absorption fine structure) provides a powerful a tool to study such colloids in their as-prepared state; in particular, it can be used determine the oxidation state of chosen species and determine whether a bimetallic colloid is alloyed or segregated.

Here, we present the results of the XAS characterisation of a series of dilute Au, Ag and Au+Ag colloids, prepared using the well-known Turkevich procedure. We will compare the results of XAFS (performed directly on the as-prepared colloids) with “traditional” characterisation techniques, particularly TEM. We will show that sequential reduction of silver onto a gold core produces segregated particles, but that reduction of a further gold shell causes increased alloying. This shows that XAFS and TEM can be used in conjunction to provide understanding of the structure of not only individual particles, but the average structure of all particles in the sample. We will also discuss the XAS characterisation of a series of bimetallic supported gold-silver catalysts prepared from solution-phase precursors.



 
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