Conference Programme

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

Session Chair: Chee Lip Gan, Nanyang Technological University
Session Chair: Tamaki Nakano, Hokkaido University
Location: Rm 301

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Presentations
4:00pm - 4:30pm
Invited

Hydrogen-Bonding States and Carrier Recombination Processes in Organolead-Bromide Perovskites

Ze Xiang SHEN1,2,3, Tingting YIN1,2, Cheng QIAN1,2,3, Jiaxu YAN2

1Centre for Disruptive Photonic Technologies, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore; 2Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore; 3Energy Research Institute (ERI@N), Interdisciplinary Graduate School, Nanyang Technological University, Singapore

Organolead-halide perovskites, with the chemical formula of APbX3 (A = CH3NH3, CH(NH2)2, or Cs, and X = Cl, Br, I), are low-cost and multifunctional materials for potential applications in solar cells, LEDs [1] and nanolasers [2], arising from their high carrier mobility, tunable electronic bandgap and long carrier diffusion length. Those excellent properties are highly correlated with their crystal structures [3] and carrier generation-recombination processes.

In this presentation, the evolution of hydrogen-bonding and CH3NH3+ (MA) cation orientations in CH3NH3PbBr3 perovskite are investigated experimentally during temperature-dependent polymorphic transformations. The H atoms in NH3+ groups form H-bonds in all three polymorphs below room temperature, but with different Br atoms in different phases. However the H atoms in CH3 groups form H-bonds with Br atoms only in the low-temperature orthorhombic phase (Fig. 1). Our results demonstrate that hydrogen-bonding plays a key role in the status of the MA cations and the tilting of the PbX6 octahedra, which in turn determine the structural stability and physical properties. [3]

In order to obtain a clearer microscopic picture for carrier generation-recombination processes in inorganic lead perovskites. Power-dependent photoluminescence (PL) from CsPbBr3 QDs and microcrystals (MCs) are studied comprehensively, the distinct responses indicate that excitation species and recombination processes are very different in the two types of samples. The MCs contain non-radiative dark states resulting a superlinear power dependent PL at low excitation power and a linear dependence at high power when the dark states are saturated; The QDs on the other hand, show linear dependence at low excitation power, while trion generation at high power induces a sublinear dependence for the exciton emission.


4:30pm - 5:00pm
Invited

Anionic Copolymerization of CO2 and Epoxides by Transition Metal-Free Initiators

Yves GNANOU

King Abdullah University of Science and Technology, Saudi Arabia

Carbon dioxide is an abundant, inexpensive, and non-toxic renewable C1 feedstock that is only used in a limited number of product-yielding reactions due to its low reactivity. Since the discovery of copolymerization of CO2 and epoxide by Inoue,[1] significant advances have however been made on this topic in particular in the past two decades with the development of highly efficient and low loading catalysts. Successful CO2–epoxide copolymerization systems involve mostly transition metal-based catalysts such as Zn(II), Cr(III),Co(III) that add alternatively CO2 and epoxide through coordination-insertion mechanism. However the multi-step synthesis of these catalysts, the toxicity and the color exhibited by the products formed due to the presence of catalyst residues are some of the issues that have prevented the transfer of this research to industry.

To address these issues an approach based on classical anionic copolymerization of CO2 and epoxydes and on their respective activation was recently considered by us. Here epoxydes are activated by Lewis acids whereas CO2 is activated by the growing cation which can be either purely organic or alkali-based; these activators are cheap, environmental friendly, commercial available and do not induce any coloration problem. In this presentation, we thus report the synthesis of polycarbonates from the copolymerization of CO2 with epoxides using this approach [2,3]. Such anionic approach could be successfully applied not only to the copolymerization of CO2 with propylene oxide and cyclohexene oxide respectively but also to the synthesis of carbonate-containing block copolymers by sequential polymerization of anionically polymerizable vinyl monomers and of CO2 and epoxydes.

References:

[1] Inoue, S.; Koinuma, H.; Tsuruta, T. Polym. Lett. 1969, 7, 287-292.

[2] Zhang, D.; Zhang, H.; Hadjichristidis, N.; Gnanou, Y.; Feng, X. Macromolecules 2016, 49(7), 2484.

[3] Zhang, D.; Zhang, H.; Hadjichristidis, N.; Gnanou, Y.; Feng, X J. Am. Chem. Soc., 2016, 138 (35), 11117.


5:00pm - 5:15pm
Oral

Progress on Silicate Nanocomposites for Environment and Energy Storage Applications

Jin QU

Center for Nanomaterials & Nanocomposites, College of Materials Science and Engineering, Beijing University of Chemical Technology, China

As a kind of traditional materials, the silicate has been used for a long time in construction industry, processing industry, food industry and so on. But there are few reports about their physicochemical properties in environment and energy storage fields. However, thanks to its various crystal structures, such as island-like, chain-like and layer-like, they are rich in exchangeable ions and natural mass transportation routes in 1-dimensinal or 2-dimensinal channels. So it not only could be used to adsorb metal ions and organic pollution for water decontamination, but also provides enough volume for lithium ions or sodium ions storage. In addition, some metal elements in silicates have multivalent state which make silicates have the oxidation/reduction property. Thus, it is very suitable for adsorption, catalysis and energy storage. These years, we design and fabricate a series of silicate nanocomposites with various nanostructures to get excellent performance as adsorbents, catalysts and Li+/Na+ storage materials. For example, core-shell structured nickel silicate/carbon nanotube is designed for lithium ions and sodium ions storage; sandwiched-like magnesium silicate/reduced graphene oxide is fabricated for high adsorption capacities of lead ions and dyes; silver silicate/carbon nanotube is synthesized for highly effective visible light photodegradation of dyes.

Acknowledgements:

Thank National Natural Science Foundation of China (51402012), the State Key Laboratory of Organic−Inorganic Composites (201404) and the Fundamental Research Funds for the Central Universities of China for the financial support.


5:15pm - 5:30pm
Oral

The Usage of Indonesia Natural Fibers to Produce Environmental Sustainable Composites

Ariadne Lakshmidevi JUWONO1, Rana HAFIZHAH1, Siti Lara OLLIVIA1, Shifa NABILA1, Seto ROSENO2

1University of Indonesia, Indonesia; 2Agency for Assessment and Application of Technology, Indonesia

The development of eco-friendly composites has been increasing in the past four decades to overcome one of the environmental problems in the world. Indonesia has a lot of natural fiber resources and their waste, which are low cost, renewable and biodegradable. These fibers have been used as the reinforcements - to get added values for these natural resources - for producing environmental-friendly composites. The aim of this study was to obtain the optimum tensile properties and deflection temperature with the variation composition of Subang pineapple leaf, Sumberejo kenaf and jutefibers respectively in polypropylene (PP)- composites. All fibers were pre-treated through alkalization process. The PP was initially produced by extrusion process, followed by fabricated the composites using a hot-press technique. The tensile test and Heat Deflection Temperature (HDT) test results showed that the optimum values of tensile strength, modulus of elasticity and deflection temperature were obtained from PP/ 30 wt% Subang pineapple leaf fiber, PP/ 40 wt% Sumberejo kenaf fiber and PP/ 40 wt% jute fiber composites. However, the best composite in the current research was PP/ 30 wt% Subang pineapple leaf fiber composite with the values of tensile strength, modulus of elasticity and deflection temperature were (64.04 ± 3.91) MPa; (3.98 ± 0.55) GPa and (156.05 ± 1.77) °C respectively, which were increased by 187.4 %, 198.6%, 264.7% respectively from the pristinePP. It was evidence from the Scanning Electron Microscope (SEM) observation on the fracture surfaces of this composite, that fiber breakage and matrix failure occurred. This indicated that the bonding between PP and Subang pineapple leaf fiber was strong.


5:30pm - 5:45pm
Oral

Cuboid-like Bi2Fe4O9/Ag with Graphene-Wrapping Tribrid Composite with Superior Capability for Environmental Decontamination

Zhong-Ting HU, Teik-Thye LIM

Nanyang Technological University, Singapore

Nanoscaled material design is an efficient method to improve the drawback of the pristine material or fabricate a multifunctional material combining the individual functions of components (e.g., catalytic, magnetic and adsorptive). As many investigations have proved that semiconductor/metal composite can exhibit enhanced photocatalysis because of the plasmonic (enhance light harvesting) and electrical conduction (charge separation) properties of noble metal nanoparticles (NPs). However, the efficiency of a photocatalyst is determined not only by the charge separation of photogenerated electron/hole pairs but also by that of the recombination effect. Herein, a ternary oxide (bismuth ferrite) is selected as the research subject and the corresponding cuboid-like Bi2Fe4O9/AgNP with graphene-wrapping tribrid nanoarchitecture was fabricated using a delicate multi-step synthesis process. It is designed to effectively enhance the performance of the pristine Bi2Fe4O9 in organic pollutants removal (up to 97% of methylene blue (MB) removal in 30 min under visible-light irradiation) through ternary collaboration among Bi2Fe4O9, silver nanoparticles (AgNPs) and reduced graphene oxide (rGO). The challenges, such as mass transfer of pollutants in water treatment, recombination of electrons/holes and interconversion between Fe(III) and Fe(II) states within Bi2Fe4O9, could be addressed effectively. The resulting samples (i.e., Bi2Fe4O9/Ag/rGO, Bi2Fe4O9/Ag and Bi2Fe4O9) were characterized by various techniques and their differences in physical and chemical properties were investigated. Meanwhile, their applications in organic pollutants removal were assessed via photo-Fenton oxidation and photocatalysis under visible-light irradiation. The findings demonstrate the individual functions of AgNP (i.e., electrical conduction, enhanced interconversion of Fe(III)/Fe(II)) and rGO (i.e., anti-recombination of electrons/holes, enhanced mass transfer of organic pollutants) within the Bi2Fe4O9/Ag/rGO composite. The schematic illustration of the mechanism of organic pollutants removal using the multi-functional Bi2Fe4O9/Ag/rGO is proposed.


5:45pm - 6:00pm
Oral

Multifunctional Microcapsules Containing 8-Hydroxylquinoline and Clove oil for Anticorrosion and Antibacterial Purposes

Yong Bing CHONG1, Chee Yoon YUE1, Jinglei YANG2

1Nanyang Technological University, Singapore; 2Hong Kong University of Science and Technology, Hong Kong S.A.R. (China)

Recently, multifunctional materials have gained desirable attention across many industries. Materials with both anticorrosion and antibacterial properties can bring immense benefits to many industries. 8-hydroxylquinoline (8-HQ) is one of the most effective corrosion inhibitors that have been widely used to prevent corrosion attack through adsorption of ions and molecules onto metal surface. On the other hand, clove oil is a natural antimicrobial compound that was found to be effective against a wide range of bacteria strains. However, undesirable interactions between these compounds and the coating matrix always result in reduction of inhibition efficiency and weakening of coating barrier properties. In this study, a mixture of 8-hydroxylquinoline (8-HQ) and clove oil was encapsulated successfully using in-situ polymerization of melamine-formaldehyde to achieve multifunctional microcapsules with both anticorrosion and antibacterial properties. The spherical shape and core-shell structure of the microcapsules were confirmed by Scanning Electron Microscopy (SEM) while Fourier Transform Infrared Spectroscopy (FT-IR) confirmed successful encapsulation. The anticorrosion performance of the fabricated microcapsules containing 8-HQ/clove oil was studied in an epoxy coating. Upon impact damage of the microcapsules, 8-HQ as the corrosion inhibitor is released to react with the metal substrate to form insoluble complexes. These complexes successfully block the active sites and retard the corrosion attack under accelerated corrosion test in 1M NaCl solution. Moreover, these microcapsules containing 8-HQ/clove oil shows great antibacterial activity against V. Coralliilyticus and E.Coli, showing their potential to treat marine fouling. These multifunctional microcapsules containing both anticorrosion and antibacterial agents were shown to be potential smart materials to tackle both problems simultaneously, which will be very useful for many industries, especially the marine industry. To conclude, this study provides a new insight into fabricating multifunctional microcapsules with dual-function of anticorrosion and antibacterial.


6:00pm - 6:15pm
Oral

Synthesis, Characterization and Catalytic Properties of Organic-Inorganic Hybrid Catalyst Me-g-C3N4 for Environmental Applications

Wen-Da OH1, Teik-Thye LIM1,2, Xiao HU1,3, Victor W.C. CHANG1

1Nanyang Environment and Water Research Institute (NEWRI), Nanyang Technological University, Singapore; 2School of Civil and Environmental Engineering (CEE), Nanyang Technological University, Singapore; 3School of Materials Science and Engineering (MSE), Nanyang Technological University, Singapore

In this study, two-dimensional organic-inorganic hybrid catalyst consisting of Me-doped g-C3N4 (Me = Co, Cu and Fe) were developed as novel redox-based advanced oxidation catalysts for sulfathiazole (STZ) oxidation via peroxymonosulfate (PMS) activation. The Me-doped g-C3N4 were prepared using a facile calcination method. The catalysts were characterized using XRD, EDX, TGA, FESEM, TEM, BET and XPS. The characterization results show that, while the pristine g-C3N4 and Me-doped g-C3N4 have a similar morphology, doping can enhance the specific surface area of g-C3N4 by at least 1.3-1.9 times. The Me is immobilized in the electron rich nitrogen cavities of g-C3N4 which contain high density of lone pair electrons. Such entrapment increases the catalytic activity of Me. It was also found that the control of the amount of Me dopant used during g-C3N4 synthesis is important as excessive Me doping can be detrimental to the catalytic performance due to the undesired undesired scavenging of reactive oxygen species by surface defects (−C≡N) and excess Me. The results indicate that the catalytic activity of Me-doped g-C3N4 is in the following order: Co-doped g-C3N4 (0.64% Co)>>Fe-doped g-C3N4>Cu-doped g-C3N4. The Co-doped g-C3N4 was selected for further performance optimization by investigating the effects of PMS dosage, catalyst loading and pH. The Co-doped g-C3N4 can be reused for multiple cycles. The Co leaching during catalytic reaction at optimum operating condition was <50 µg L−1 (<0.1%) indicating that the catalyst is highly stable. Overall, the Me-doped g-C3N4/PMS system can be considered as an effective advance oxidation technology for eliminating sulfonamide antibiotics in water.



 
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