Day 2 :
Keynote Forum
Michael O Wells
Reynolds Polymer Technology, USA
Keynote: Use of combination crp-thermal cure in free radical bulk polymerization systems
Time : 09:30-10:05
Biography:
Michael Wells has served in various positions within the polymer industry for 30 years. He has held positions with such organizations as Procter and Gamble, A. O. Smith, Witco, Arkema, and currently holds the position of Director of Research and Development for Reynolds Polymer Technology. He is a graduate of Arkansas State University with a Bachelor’s in Chemistry and Lehigh University with an M. Eng. In Polymer Science and Engineering. He was until recently, President of the Rocky Mountain section of the Society for Plastics Engineers, and previously served on the board of the Lehigh Valley section of SPE. His main areas of research are polymer initiation systems and polymer structure/property modification. More recently, he has been working with flame retarded acrylic materials and adhesives. He holds two US patents and 1 application in process. Michael currently resides in Grand Junction, Colorado.
Abstract:
In a series of studies carried out several years ago, some papers were presented covering the research efforts involved with using Controlled Radical Polymerization techniques in radically cured thermosetting resins. Among the positive attributes that were shown are: improved stability of initiated resins, longer potlife, the ability to create b-staged polyester materials, and most interestingly, the ability to drastically improve mechanical properties. The most noticeable ability of these unique molecules is that property of developing a two-way, reversible, “on-off” type of complex with a growing polymer chain. Since this property is dependent upon the monomeric composition and the processing temperature of the application technique, this particular technology can be used to tailor initiator systems to particular applications and conditions. The overriding question in the middle of these findings is, “what characteristic of these systems causes such changes in mechanical properties?” In this paper, an attempt is made to look mechanistically at the resins created and correlate these improvements to: molecular weight changes, changes in the molecular weight between crosslinks, changes in free volume within the matrix, changes in order/crystallinity within the resin matrix, and changes in crosslink density. It is assumed that through these studies, a better understanding of why radical controllers used in small quantities can make such profound differences in radically cured resins
Keynote Forum
Joseph D Lichtenhan
Hybrid Plastics Inc., USA
Keynote: Hemostasis with POSS® silanols
Time : 10:05:-10:40
Biography:
Joseph D Lichtenhan, Ph.D. Is a co-founder of Hybrid Plastics Inc. Dr. Lichtenhan is a pioneer and world authority in the field of POSS® additives. POSS has been hailed as the first entirely new chemical class of monomers to be developed since 1955. His insights into their commercial utility launched the global sales for POSS® in 1998. Dr. Lichtenhan has excelled at technology transition and the establishment of a global footprint for POSS® via innovative sales and marketing techniques.
Abstract:
Statement of the Problem: A single "perfect" hemostat cannot exist due to the wide range of injury types experienced by humans and animals. However, a leapfrog advancement in hemostatic devices is desperately needed to address noncompressible hemorrhagic bleeding. More specifically, injuries to arteries in the neck, internal organs, or groin require immediate surgical attention because these types of hemorrhages do not adequately respond to compression or packing. Despite extensive and admirable work to increase blood clotting rates, the clotting cascade alone doesn’t react fast enough, in these types of injuries, to arrest fluid loss from an artery. While hemorrhagic bleeding is often associated with battlefield trauma or acts of terrorism, uncontrolled hemorrhages can also occur in a wide range of incidences, ranging from automobile and plane accidents to recreational and home repair accidents. Nearly all hemorrhagic bleeding is initially addressed by a first responder who may or may not have any or adequate medical training for such trauma. Therefore, one of the first requirements for developing a hemostat that works on noncompressible bleeding is for it to have high deployability and intuitive application. This would be analogous to use of a fire extinguisher “point at the base of flame and squeeze handle”. Next, the hemostatic agent needs to be proliferative, meaning that it is capable of translating within the wound channel to the source of the hemorrhage, even if it is not visible. Finally, the hemostatic agent must be effective without compression. This latter point is critical considering that only minor amounts of compression may be possible for the neck, internal organ, and groin hemorrhage. POSS additives are known to enhance medical and personal care products and have been in the UK and US markets for several years. In particular, a liquid trisilanol hepta-iso-octyl POSS is uniquely well suited for use as a hemostatic device for non-compressible bleeding. Upon contact with blood trisilanol, hepta-iso-octyl POSS rapidly prevents fluid loss and simultaneously forms a viscoelastic polymeric clot (thrombus) with blood components. The mechanism of action for the POSS viscoelastic hemostat, along with its comparative performance relative to other hemostatic devices will be presented. This presentation will include in vitro and in vivo findings.
Keynote Forum
Motoyasu Kobayashi
Kogakuin University, Japan
Keynote: Interaction between polymer brushes bearing phophorylcholine and inverse: Phophorylcholine groups
Time : 11:00-11:35
Biography:
Kobayashi received his Ph.D. in 2000 from the Tokyo Institute of Technology, Japan, and was appointed as an assistant professor in the Faculty of Engineering, Yamagata University, Japan (200-2004). From 2004 to 2005, he worked as a researcher at Kyushu University, Japan, and was appointed as an assistant professor in the Institute for Materials Chemistry and Engineering, Kyushu University, in 2006. He has been a group leader of the JST-ERATO project (2009-2013). After that, he moved to Kogakuin University in 2013 as an associate professor and has been full professorship since 2014. His research interests are polymer synthesis, bio-inspired chemistry, surface and interface science, such as wettability, adhesion, and the tribology of ion-containing polymers. He has been published more than 70 scientific articles, and 20 books/book chapters.
Abstract:
Phosphocholine (PC) is a zwitterion group which can be found in phosphatidylcholine lipids of the cell membrane in nature. It is widely known that the polymer bearing PC group reveals excellent bio-compatibility and antifouling properties due to extremely weak interaction between PC and protein molecules. In this work, an adhesive interaction of polyzwitterion brushes containing sulfo- and phospho-betaine groups in water was estimated by force curve measurement using scanning probe microscopy. Polyzwitterion brushes with a 110 nm thick (dry state) on a silicon wafer were prepared by surface-initiated atom transfer radical polymerization of methacrylate monomers bearing sulfobetaine (SB), PC, and inverse-PC (iPC). Inverse PC is a zwitterionic group having inverted charge orientation of quaternary amine and phosphate in contrast to PC. Chemical structure of polymers with PC and iPC
Force curve measurement on (a) poly(MPC) brush and (b) poly(MiPC-iPr) brush surface in water by using PC or iPC functional groups-immobilized silica probe Force curve measurement were performed by atomic force microscopy using a handmade sphere probe. Silica particle (d = 20 μm) covered with SB, PC, and iPC functional groups was immobilized at the edge of a tipless cantilever with a small amount of epoxy resin. Adhesion force on the surface of SB and PC brushes were lower than 1 nN, whereas larger force than 20 nN was obtained between PC and iPC brush (Figure 2). A specific strong attractive interaction between PC and iPC were clearly observed. Poly(SB) brushes showed temperature dependency of adhesive interaction corresponding to the UCST behavior in water.
Keynote Forum
Boxin Zhao
University of Waterloo, Canada
Keynote: Dopamine-functionalized polypyrrole nanostructures
Time : 11:35-12:10
Biography:
Boxin Zhao is a tenured associate professor at the University of Waterloo. He has created and directed the Laboratory of Surface Science and Bionanomaterials, working on both fundamental and applied research. He has 180 publications in total; 89 are peer-refereed papers on the top journals including Langmuir, Macromolecules, Advanced Materials, and Advanced Functional Materials, PNAS. The current research interests of his group are in the areas of polymers and multifunctional composites, interfacial technologies and surface science, biomimetic adhesion and adhesives, 3D printing, interfacial phenomena and contact dynamics in polymers and biological systems.
Abstract:
Surface modification and functionalization of polymers are playing increasingly important roles in the development of new functional materials with desired properties for applications in the advanced manufacture, energy, healthcare etc. Polypyrrole (PPy) is one of the most interesting and well-studied electrically conductive polymers because of its long-term stability and good biocompatibility. However, PPy is difficult to be further functionalized and processed because PPy is in a form of black precipitate that is insoluble in water and in most organic solvents, and has a weak adhesion to surface. In this talk, I will review our recent research development on the use of catechol chemistry for the functionalization of polypyrrole and the fabrication of varied catechol-polypyrrole nanostructures with tunable morphologies and conductivities and discuss their potential applications. Inspired by the catechol and amine functional groups found in the adhesive proteins of marine mussels, we have exploited one of the simplest catecholamines, dopamine (DA), for surface modification and functionalization of PPy. Even though dopamine is insulating, adding a small of dopamine can surprisingly increase the conductivity of polypyrrole. We attributed this feature to the molecular adhesion of dopamine with polypyrrole resulting in the formation of hydrophilic core/shell nanofibers, which are readily dispersible and provides more effective electrical pathways than the globular nanoparticle without dopamine. It was also found that the morphology and conductivity of the dopamine (DA)-functionalized polypyrrole (Py) could be finely controlled by the DA/Py reaction ratio. For instance, at higher reaction ratios, we observed the morphologies of nanoflakes, which are less conductive but can be used in electromagnetic interference shielding applications.
Keynote Forum
Aman Ullah
University of Alberta, Canada
Keynote: Biomaterials from renewable lipids
Time : 12:10-12:45
Biography:
Ullah received his PhD in Chemical Sciences and Technologies in 2010 at the University of Genova, Italy working together at Southern Methodist University, USA. He worked as a postdoctoral fellow, Assistant Professor and was promoted to Associate Professor with Tenure at the University of Alberta. He teaches a graduate course which deals with fundamentals in bio-based materials development, characterization, and various industrial applications. Aman has published more than 42 papers in reputed journals and 4 patents/patent applications. He has participated and presented his work at more than 90 National and international scientific meetings and conferences, including several invited, keynote and plenary lectures at conferences and research centers in Asia, Europe, and America. In addition, he has received several awards including Canadian Rising Star award in Global Health by Grand Challenges Canada
Abstract:
In recent years, the use of renewable natural resources has become the focus of research in supplementing and replacing traditional petrochemical products due to growing energy demands and environmental concerns. The utilization of lipids has been considered to play a primitive role towards sustainable development due to their large-scale availability, built-in-functionality, biodegradability and no net CO2 production. In addition, a broad range of monomers can be obtained from lipids as a single feedstock. These attributes make lipids a good fit for the development of renewable biomaterials. This Presentation will focus on the conversion of lipids, from various sources including waste streams such as waste cooking oil and lipids extracted from spent foul, into monomers, biopolymers, and biomaterials. The ability for complete conversion of oils in just a few minutes under solvent-free conditions into monomers, biopolymers, and bio-composites is undoubtedly an attractive concept from both an academic and an industrial point of view.
Keynote Forum
Lee D. Wilson
University of Saskatchewan, Canada
Keynote: Development of responsive biopolymer materials: Investigation of their structure and adsorption properties
Time : 13:45-14:20
Biography:
Wilson is affiliated with the Department of Chemistry at the University of Saskatchewan and is an Associate Professor with research interests that cover diverse topics in physical chemistry, materials science and environmental chemistry. Ongoing research activities are focused on the development of new types of materials and studies related to adsorption and interfacial phenomena related to water science and technology. The Wilson lab is developing new forms of sustainable biomaterials for the controlled removal of contaminants from water and chemical separations using methods based on green chemistry. This research contributes to the science and technology of “smart” adsorbent materials and applications that range across water and energy security.
Abstract:
Statement of the Problem: There is a need to develop improved biopolymer adsorbents with responsive properties and enhanced adsorption toward target species for specialized applications in water treatment. In this study, polymer brushes and their iron oxide composites were prepared and characterized, along with the efficacy of methylene blue (MB) removal from aqueous solution. These “smart” materials were designed by grafting biodegradable polymers, polyacrylic acid (PAA) or poly itaconic acid (PIA) onto chitosan to yield pH-responsive polymer brushes of PAAgCHI, PIAgCHI and their magnetic nanocomposites (MNCs) containing iron oxide, respectively (Fig. 1). The MNCs are pH-sensitive and magnetically responsive adsorbents with switchable polymer morphology between swollen and collapsed states, along with the controlled adsorption and desorption of MB. Switchable MB uptake is based on the pH driven molecular recognition and conformational changes of brushes. The adsorption capacity of the materials varies between 421.2 to 470.2 mg g–1 with a removal efficiency of 99.2% (Fe3O4–PIAgCHI) and 99.5% (Fe3O4–PIAgCHI) for the MNCs. Sorbents can be recovered and efficiently regenerated by switching the pH of a solution under an applied external field over five recycle steps. This work illustrates the potential utility of “smart” polymer brush systems for the remediation of model cationic dyes in wastewater. These eco-friendly sorbent materials possess excellent adsorption capacity, modular design, low cost, excellent regeneration, and rapid separation. Potential applications of these materials include the controlled removal of antimicrobials, pesticides, and personal care products from water and wastewater streams with high efficiency and recovery.
- Sensor Materials | Composites |Energy Materials |Nano Particals | Non-Metallic Solid Materials | 2D and 3D Imaging | Advanced Functional Materials | Materials Structure Mechanics | 3D and 4D Materials Science |Materials Synthesis & Processing |Surface Chemistry |Nanostructured Materials |Organic Materials |Materials Sustainablity |Nanomaterials in Medical Applications |Electrocatalysis |Organometallic Synthesis
Location: Frederick
Session Introduction
Yasser Hassan
Oxford University, UK
Title: Facile synthesis of air-stable and highly luminescent red- and blue-emitting perovskite nanocrystals for efficient light emitting devices
Time : 15:20-15:40
Biography:
Yasser Hassan has his expertise in the synthesis of semiconductor nanocrystals (NCs) and their application in the state-of-the-art engineering of efficient and low-cost thin-film optoelectronic devices, solar cells and light diodes (LEDs). He is currently a Postdoctoral Research Associate at the Oxford Photovoltaics and optoelectronics Devices Group under Prof. Henry Snaith, University of Oxford. Prior to his current position, he completed his PhD of Chemical Engineering and Applied Chemistry in 2016 from the University of Toronto. Currently, his core contribution focuses on the creation of highly efficient white LEDs with high brightness combined with operational durability. He examines a wide range of different highly emissive and stable perovskite NCs (2D and 3D) emitters, with controlled size and surface structure, which have the desirable emission band gap to cover the whole panchromatic absorption profile with the focus on their optoelectronic applications
Abstract:
Metal halide perovskites are promising candidates for use in light emitting diodes (LEDs), due to their potential for colour tuneable and high luminescence efficiency. While recent advances in perovskite-based light emitting diodes (PeLEDs) have resulted in external quantum efficiencies (EQEs) exceeding 12.4 % for the green emitters, and infrared emitters based on 3D/2D mixed dimensional perovskites have exceeded 15%, the EQEs of the red and blue emitters still lag behind. A critical issue to date is creating highly emissive and stable perovskite emitter with the desirable emission band gap (especially red and blue region) to achieve full-colour displays and white LEDs. A critical issue to date is creating highly emissive and stable perovskite emitter with the desirable emission band gap (especially red and blue region) to achieve full-colour displays and white LEDs. Herein, we report the preparation and characterization of a highly luminescent air-stable suspension of both red cubic CH3NH3PbI3 perovskite nanocrystals (NCs) and high-quality, stable blue colloidal perovskite CsPbBr3 nanoplatelets. Both the red NCs and the blue nanoplatelets exhibit controlled optoelectronic properties with colour purity in the recommended emitting regions (according to Rec. 2020) of band gaps of 1.96 and 2.65 eV, respectively. Photoluminescence quantum yields (PLQY) exceeding 95% for the red NCs and 92% for the blue was achieved. We demonstrate the utility of these nanocrystals in PeLEDs
Alan F. Jankowski
Sandia National Laboratory, USA
Title: Interdiffusion kinetics in Cu-Ni(Fe) nanolaminate structures
Time : 15:40-16:00
Biography:
Alan Jankowski completed his PhD in Mechanics and Materials Science at Rutgers University in 1987 and has held scientific, faculty, and management positions at Lawrence Livermore National Laboratory, the Texas Technological University, and Sandia National Laboratory. He has published 135 journal papers, received 29 US Patents, and given 40 invited presentations at international conferences
Abstract:
The decomposition of a one-dimensional composition wave in Cu-Ni(Fe) nanolaminate structures is quantified using x-ray diffraction to quantify the kinetics of interdiffusion processes. A schematic of an A/B nanolaminate structure with A (dark-shaded) and B (light-shaded) atoms is shown (below left) as viewed in cross-section. Features are shown such as a threading dislocation (d), grain boundary (gb) between columnar grains, and the A/B layer pair thickness, i.e. the composition wavelength (lA/B). Cu-Ni(Fe) is a spinodal alloy system where the growth or decay growth of the composition modulation occurs within or above the critical temperature for the chemical spinodal, respectively. A transmission electron microscope, bright-field image and selected area diffraction pattern (insert) are shown (below right) for a Cu-Ni(Fe) nanolaminate with a 4.34 nm composition wavelength, revealing its ultra-fine grain nanocrystalline structure. Evidence of a negative interdiffusivity is found for each of sixteen different nanolaminate samples that are aged at room temperature over a composition wavelength range of 2.1–10.6 nm. A diffusivity value ÄŽ of 1.77 × 10−24 cm2·s−1 is determined for the alloy system at room temperature – perhaps, the first such measurement at a ratio of melt temperature to test temperature that is greater than 5. Although this diffusivity value is extremely small, it is several orders of magnitude greater than that value extrapolated from high temperature to room temperature for a bulk diffusion mechanism. Diffusion mechanisms that are operative from room to high temperatures for the Cu-Ni(Fe) nanolaminate structures (shown in the image below) are reviewed, including the possible effects of short-circuit diffusion through interlayer grain boundaries.
Mehry Fattah
York University, Canada
Title: Microstructure and surface properties study of plasma nitrided aisi 4140 low alloy steel at different temperatures
Time : 16:20-16:40
Biography:
Mehry Fattah is a researcher and engineer who has the experience of working within academia and industry on surface engineering, corrosion, and coatings for 9 years. She received her Ph.D. and MSc from Amirkabir University in Metallurgical Engineering (University of Toronto Canadian Accreditation Equivalency). She has successfully proposed a corrosion model that shows how microstructure and composition affect the corrosion mechanism, which leads to lower cost and more efficient solutions to protect the surface deterioration through general and pitting corrosion. She conducted cathodic protection designs which resulted in increasing lifespan and saving money in Oil and Gas industry. She has conference and ISI papers published as the result of her works. She enjoys facing new challenges and forging ahead to find the solutions under tight time frames while inspiring team members.
Abstract:
In this paper, the influence of plasma nitriding and treatment temperature on the corrosion and hardness properties, microstructure and composition of AISI 4140 low alloy steel was investigated. Plasma nitriding treatments carried out in a gas mixture of 85% N2-15% H2, for 5 h at a chamber pressure of 4 mbar at different treatment temperatures varying from 520 to 620 °C. Optical microscopy, scanning electron microscopy, X-ray diffraction, hardness and microhardness measurements and potentiodynamic polarization technique in 3.5% NaCl solution, was used to study the plasma nitrided low alloy steel. The results revealed that plasma nitriding at temperatures between 520 and 570°C can produce a ε phase dominant compound layer which is supported by a diffusion zone. With increasing the treatment temperature from 570 to 620°C, γ′ phase appeared. The thickness of the compound layer and diffusion zone increased with increasing the treatment temperature. The thickest compound layer was produced in the sample was treated at 620°C, composed of two outer and inner layers with different microstructures and compositions and the maximum amount of nitride phases was detected at the depth of 20- 35µm from the surface. The hardness of the surface remarkably improved after plasma nitriding and reached up to a maximum of 945 HV0.05 at 520°C which is almost 5 times higher than of the untreated sample.
Corrosion resistance increased after plasma nitriding at 520°C and continued to increase with increasing the treatment temperature to 545°C. With further increase of temperature from 545°C to 620°C, corrosion resistance decreased to the amount of the untreated sample. The sample treated at 545°C showed the most improved corrosion resistance while simultaneously attained surface hardness as high as about 4 times of the untreated sample.
Sherif Mostafa
University of Calgary, Canada
Title: Room temperature VOCs sensor based on microwave-intensive pulsed light treated TiO2-SnO2/ CNTs hybrid nanocomposite
Time : 16:40-17:00
Biography:
Sherif Mostafa is a postdoctoral fellow at the University of Calgary. He works as a Manager of an analytical chemistry laboratory. He has MSc degree in 2005 in chemical engineering with Thesis Title " Fiber Treatment for Reduction of Radar Signature ".Also, he has Ph.D. degree in 2014 in chemical engineering with thesis title " Creation of Advanced Ceramic Materials in Nanotechnology Range". He has experience in nanoceramic materials synthesis, water treatment, decontamination, antibacterial materials, RAM and preparation of gas sensing materials. Sherif participates in many types of research in different fields. He supervised many types of research in various fields
Abstract:
SnO2 and TiO2 were loaded onto multi-walled carbon nanotubes (MWCNTs) to form a new composite for the sensing of volatile organic compounds (VOCs). To do this, MWCNTs were dispersed into mixtures of 0.5 wt.% SnO2/TiO2. The TiO2 was converted from anatase to rutile phase through the use of rapid microwave and intense pulsed light techniques. These processes are also used for drying to obtain the materials as a dry powder. The materials were then incorporated into a solution of 5 wt.% polyvinyl butyral (PVB) to form a sol-gel. A gas sensing device was formed by spin coating the materials onto quartz crystal microbalance (QCM). FE-SEM and XRD characterizations indicated that the inclusion of CNTs did not affect the particle size or the morphology of the thin film. Most importantly, the sensor based on the SnO2-TiO2-MWCNT hybrid showed the high and fast response, high selectivity to VOCs relative to hydrogen gas and good stability. Mass and molar adsorption was calculated based on changes in the frequency by the Sauerbrey model. The sensing properties were investigated with different VOCs including ethanol, methanol, isopropanol, and toluene at different concentrations and operating temperatures. Room temperature sensing was achieved and the highest sensitivity was shown towards ethanol with a response time as low as 5 seconds.
Mirnmoy Misra
Gachon University, South Korea
Title: Enhance piezophototronic photocatalytic activity of ZnO nanorods embedded on flexible PDMS sheet
Time : 17:00-17:20
Biography:
Mrinmoy Misra is an Assistant Professor at the Department of Bionano Technology, Gachon University, South Korea. He graduated with a Ph.D. from Academy of Scientific & Innovative Research, India. He has received awards such as Indian Institute of Technology Kanpur postdoctoral fellowship, 2015, Award of science & engineering research board (SERB) National Post-Doctoral fellowship, 2016. His research interests include thin-film fabrication, nanomaterial-based sensor, photocatalytic materials, nanoparticle synthesis and characterization and solar cells. Dr. Misra has authored 13 research articles in SCI journals
Abstract:
In this paper, we generate piezoelectricity in one-directionally aligned bi-axially grown ZnO nanorods. The applied force is horizontal to the polarization direction. The piezo-phototronic induced voltage generated from a bending radius is experimentally measured for ZnO NRs. The combination of the photocatalytic effect and piezoelectrochemical phenomenon of ZnO NRs has been used for the degradation of an organic pollutant in the aqueous medium. The mechanical stress creates a polar charge field on the surface of ZnO NRs, which acts as a driving force to enhance the charge separation of photogenerated electron and hole pairs. Subsequently, the charge separation increases the photocatalytic activity of ZnO NRs. Further, coumarin (COU), used as a fluorescent probe for the purpose of detection and measurement of OH. radical is generated during photocatalysis process. The synergistic effect of strain-induced chemical reactions and UV photocatalytic activity can deliver a lucrative approach for degradation of organic pollutants. In addition, this work exhibits an exciting new model of a piezo-phototronic device.
Ramya Nair
Bhabha Atomic Research Centre, India
Title: Structural and luminescence properties of GdBO3:Eu in different crystalline modifications
Time : 17:20-17:40
Biography:
Ramya Nair completed her M.Sc. from University of Mumbai with an outstanding grade in the year 2012. During the master's program, she successfully completed six-month dissertation work at Tata Institute of Fundamental Research(TIFR), Mumbai. Afterward, she got selected in prestigious DAE fellowship scheme for Ph.D. in basic sciences and currently she is pursuing her research work as the senior research fellow at Chemistry Division of Bhabha Atomic Research Center, Mumbai. She has five papers published in journals of international repute and participated in several international conferences and workshops.
Abstract:
GdBO3 belongs to the category of rare earth borates. Its outstanding optical properties with high thermal and chemical stability enable them as potential candidates for solid-state lighting, plasma display panels etc. The motivation of this work is to understand the influence of local environments on luminescence properties of Eu3+ in three different phases of GdBO3, namely monoclinic, triclinic and nano-crystalline forms as this will be helpful for selecting a suitable host for getting optimum luminescence and to get a basic understanding on phase and local environment dependent optical parameters. GdBO3 containing 1at.% Eu3+ were prepared in nano-crystalline, monoclinic and triclinic forms in the present study based on hydrothermal, polyol and solid state reaction of B, Gd and Eu precursors and subjected structural and luminescence studies. TEM images and SAED patterns confirmed the formation of nanorods of GdBO3 having the monoclinic structure (length~ 200 nm, width ~10 nm) while FTIR patterns have confirmed that in nanorods and triclinic phase boron exists in both diagonal and tetrahedral configurations. Unlike this in monoclinic GdBO3 boron exists only as BO4 structural units constituting B3O99- groups. The relative intensity ratios of electric dipole allowed to magnetic dipole transitions of Eu3+ in triclinic and nanorods of GdBO3 are 2 and 2.3 respectively and are found to be higher than that of monoclinic phase (1.4). The CIE colour coordinates are found to be (0.60, 0.34) for monoclinic, (0.64, 0.36) for triclinic phases and (0.62,0.35) for nanorods, suggesting that the nanorods have improved red colour characteristics compared to the other two forms
Haijin Liu
Henan Normal University, China
Title: Fabrication of binary heterojunction photocatalysts with enhanced photocatalytic activity
Time : 18:00-18:20
Biography:
Haijin Liu got her Ph.D. degree in 2010 in environmental science. She works at Henan Normal University as an associate professor. She has been focused on the synthesis of new functional materials and their applications in the environmental area. She has fabricated various functional materials and applied them to adsorption, degradation, energy storage, disinfection, and so on. She worked deeply into the degradation processes and explored different mechanisms. As a visiting scholar, she collaborated with Dr. Aicheng Chen at Lakehead University in Canada during 2013-2014 and worked with Huijun Zhao at Griffith University in Australia in 2016. She hosted and participated in many Chinese projects and owned several Chinese patents.
Abstract:
Statement of the Problem: Photocatalytic technologies, as promising strategies for environmental control, have broad and attractive prospects for the degradation of water and air resident pollutants. However, most single photocatalysts possess some defects, such as narrow light absorption range, the high recombination rate of photo-induced electrons and holes and so on.
Methodology & Theoretical Orientation: In this study, binary heterojunction photocatalysts, SnS2/Bi2MoO6 and SnO2/BiOBr were synthesized by mild hydrothermal methods for the first time. The photocatalytic activities of these materials were evaluated through the degradation of a series of organic pollutants, which possess stable chemical structures, intense carcinogenicity, as well as being recalcitrant to degradation.
Findings: The experimental results indicated that the SnS2/Bi2MoO6 and SnO2/BiOBr composites exhibited significantly enhanced performance in contrast to pure Bi2MoO6, SnS2, SnO2 or BiOBr. In details, the degradation rate constant of CV (crystal violet) using 5 wt% SnS2/Bi2MoO6 photocatalyst was 3.6 times that of the Bi2MoO6 and 2.4 times that of SnS2; the degradation rate of RhB attained ~98.2% in 20 min. using 30 wt% SnO2/BiOBr, which was close to twice that of pure BiOBr, and 10 times that of pure SnO2. Furthermore, the primary active species in the photocatalytic oxidation process were detected via radical trapping experiments and ESR spectra.
Conclusion & Significance: Two photocatalytic mechanisms were proposed according to the different systems above to elucidate the improvement in photocatalytic efficiency. We trust that the work may provide further knowledge of the design and synthesis of advanced photocatalysts, as well as to inspire further applications of photocatalysts for water purification under visible light irradiation