Seminars 2021

TitleApplications of Phase Change Materials as Thermal Storage Materials
Speaker:Dr Zhu Qiang 
Date:3 August 2021
Time:11.30am to 12.00pm
Venue:Zoom (ID and PW will be given upon registration)
Host: Professor Atsushi Goto 
Abstract: 

Phase Change Materials (PCMs) are widely recognized for their energy storage and thermal regulation functions. They bring about a cooling effect by absorbing excess heat in the form of latent heat (and vice versa), hence maintaining temperatures in the desired region. PCMs are commonly applied in building envelopes, logistics, electronics, batteries, and other sectors for temperature regulation and energy harvesting. For example, PCMs can be added to concrete used for buildings to help reduce the internal temperatures and improve the level of comforts of residents, which will bring about a trickle-down effect in energy costs savings and lower pollution levels. In this presentation, Dr Zhu Qiang will be sharing on ways to develop a more efficient PCM system to harness its optimal potential. He will also share his experience in developing PCM-based materials for various applications. In order to support the PCM technology development, Dr Zhu’s group has also built up various testing facilities/testbed to evaluate PCM materials for cooling solutions in buildings and logistics. This testbed gives a realistic indication on how the material may perform in actual applications, helping to resolve many testing requirements for the industry partners. This webinar hopes to be able to foster a greater interest in PCM and link companies and institutions together for more exciting research and collaborations.

TitlePhotothermal Nanomaterials: Synthesis and Applications
Speaker:Dr Ye Enyi
Date:3 August 2021
Time:11.00am to 11.30am
Venue:Zoom (ID and PW will be given upon registration)
Host: Professor Atsushi Goto 
Abstract: 

Light-matter interaction is of great interest for centuries, among which light-to-heat conversion draws much attention in the past few decades. The exploration of photothermal nanomaterials with high light-to-heat conversion efficiency paved the way for their practical applications. In this seminar, Dr. Ye Enyi will talk about the photothermal effect of different categories of light-absorbing nanomaterials, together with the synthetic methodologies for preparation of various photothermal nanomaterials. He will also present the biomedical applications and solar steam generation etc. of the photothermal nanomaterials, focusing on metallic nanomaterials, 2D materials, semiconductors and carbon-based nanomaterials. In addition, Dr. Ye will also give a brief introduction of other research areas in his group, he would like to share his experience on how he managed to build up the formulation platform in IMRE catering to local SME’s needs. 

TitleGreen and Functional Materials from Lignocellulosic Waste
Speaker:Dr Kai Dan 
Date:3 August 2021
Time:10.30am to 11.00am
Venue:Zoom (ID and PW will be given upon registration)
Host: Professor Atsushi Goto 
Abstract: 

In light of the incessant global consumption of raw materials, the search for sustainable resources is significantly crucial. Lignocellulosic biomass, being the most naturally abundant material, have always been treated as agricultural/food waste or used in low-value applications. Our team focuses on the development of functional materials based on lignocellulosic materials. We are capable of generating a variety of functional lignin-based polymers, integrated with both the intrinsic features of lignin and additional properties of the grafted polymers. These modified lignin can be processed into various functional materials for different applications. Our team is also exploring the value-added applications of other agri/food materials, such as spent coffee grounds and coconut husks.

TitleThe Path from Photons to Chemical Bonds
Speaker:Professor Prashant K. Jain
Date:5 March 2021
Time:9.30am to 11.00am
Venue:Zoom (ID and PW will be given upon registration)
Host: Dr Zhang Zhengyang 
Abstract: 

In recent years, it has been found that noble metal nanoparticles catalyze chemical reactions when their plasmon resonances are excited by light radiation. I will discuss this emerging paradigm in chemistry and elucidate how it works. Photoexcitation of plasmon resonances in noble metal nanostructures leads to the generation of electron–hole pairs, which can be utilized as reaction equivalents in redox chemical processes. A striking example of this phenomenon is the multielectron conversion and C–C coupling of CO2 to form hydrocarbons on gold nanoparticles under visible light. The lack of such activity in the dark suggests that reaction pathways are modified by optical excitation and so are the very catalytic properties of the plasmonic metal. In the case of thermodynamically uphill reactions, chemical potential is harvested from optical excitations and stored in the form of energy-rich bonds. Finally, I will show that under visible-light excitation, discrete, individual chemical reaction events can be imaged on a single plasmonic nanoparticle.

TitleSingle Molecule Imaging of Chemical Processes on Nanocatalysts
Speaker:Associate Professor Fang Ning
Date:3 March 2021
Time:9.30am to 11.00am
Venue:Zoom (ID and PW will be given upon registration)
Host: Dr Zhang Zhengyang 
Abstract: 

Real time imaging of single catalyst active sites in situ enables mechanistic studies on fundamental reaction steps under actual turnover operando conditions; these studies have enormous potential impact in establishing intimate structure-property relationships from which to build better (faster, cleaner, cheaper) catalysts. Our research aims to design catalytic platforms for single molecule imaging and reveal molecular dynamics (including diffusion, adsorption, and chemical conversion, as well as their coupling) on the nanocatalyst surfaces or in the nanoporous structures at the single-molecule level.

(1) Nanoconfinement could dramatically change molecular transport and reaction kinetics in heterogeneous catalysis. A core-shell nanocatalyst with aligned linear nanopores has been specifically designed for single-molecule studies of the nanoconfinement effects. The quantitative single-molecule measurements revealed unusual lower adsorption strength and higher catalytic activity on the confined metal reaction centres within the nanoporous structure. More surprisingly, the nanoconfinement effects on enhanced catalytic activity are larger for catalysts with longer and narrower nanopores. Experimental evidence, including molecular orientation, activation energy, and intermediate reactive species, has been gathered to provide a molecular level explanation on how the nanoconfinement effects enhance the catalyst activity, which is essential for the rational design of high-efficiency catalysts.

(2) The insightful comprehension of catalytic dynamics in structural defects of two-dimensional (2D) layered material is crucial for rational design of high-performance catalysts via defect engineering. Nevertheless, conventional ensemble measurements do not have sufficient spatial resolution to differentiate the catalytic dynamic behaviors between defects and bulk materials, while theoretical calculations with simplified models do not account for complexity and heterogeneity in realistic systems. Here, we unveiled the heterogeneous photocatalytic dynamics in defects of 2D InSe in situ by single-molecule imaging. Specifically, we deconvoluted individual steps (reactant adsorption/desorption, chemical conversion, product dissociation and diffusion) in the overall photocatalytic processes and quantitatively compared their heterogeneous dynamic properties at different structural features. We further established the correlations between photocatalytic dynamic properties and intrinsic lattice structures, electronic energy levels, surface diffusion behaviors, and layer number of bulk materials.

(Representative Publications: Nat. Catal. 2018, 1, 135; Nat. Commun. 2019, 10, 4815; J. Am. Chem. Soc. 2020, 142, 13305; J. Am. Chem. Soc., 2014, 136, 1398; Angew. Chem. Int. Ed., 2014, 53, 12865; Chem. Rev. 2017, 117, 7510.)

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TitleUltrafast spectroscopy and imaging of photochemical reactions
Speaker:Professor Toshinori Suzuki
Date:19 February 2021
Time:3.00pm to 4.30pm 
Venue:Zoom (ID and PW will be given upon registration)
Host: Associate Professor Loh Zhi Heng 
Abstract: 

Chemists have unravelled atomistic details of invisible chemical reaction mechanisms using imagination and logical thinking based on carefully designed control experiments. However, it is a longstanding dream of chemists and students to be able to watch chemical reactions directly and understand their mechanisms. The dynamics of photochemical reactions consist of electronic dynamics (ultrafast change of an electronic state) and structural dynamics (nuclear motions and structural deformation). Various experimental methods are newly developed and applied to investigate these aspects of chemical reactions. In this talk, I would like to provide a brief overview on the recent advances in ultrafast spectroscopy and imaging of photochemical reactions including my own research on the electrocyclic ring-opening reaction of 1,4-cyclohexadiene and others.

TitleSnapshots of primary photoinduced events in biomolecules by tunable few-optical-cycle pulses
Speaker:Professor Giulio Cerullo
Date:5 February 2021
Time:4.00pm to 5.30pm
Venue:Zoom (ID and PW will be given upon registration)
Host: Associate Professor Loh Zhi Heng 
Abstract: 

Many light-induced processes in biomolecules, such as energy relaxation, energy/charge transfer and conformational changes, occur on ultrafast timescales, ranging from 10-14 to 10-13 s. The speed of such elementary processes is intimately linked to their efficiency, making ultrafast optical spectroscopy an invaluable tool for their investigation [1]. Pump-probe and the emerging multidimensional spectroscopies require short pulses, in order to observe fast dynamics, and broad frequency tunability, to excite a system on resonance and probe optical transitions occurring at different frequencies. Optical parametric amplifiers are ideal tools for such experiments, because they provide frequency tunability and support broad gain bandwidths, enabling the generation of pulses with duration down to a few optical cycles and tunability from the IR to the UV [2]. In this talk I will introduce the principles of ultrafast optical spectroscopy and give examples of its application to the study of important photoinduced processes, such as energy/charge transfer in natural and artificial light-harvesting complexes [3], the isomerization of rhodopsin which triggers the primary event of vision [4] and conical intersection events underlying photoprotective mechanisms of DNA [5]. For Zoom registration:

Reference: [1] M. Maiuri et al., J. Am. Chem. Soc. 142, 3 (2020). [2] C. Manzoni and G. Cerullo, J. Opt. 18, 103501 (2016). [3] S.M. Falke et al., Science 344, 1001 (2014). [4] D. Polli et al., Nature 467, 440 (2010). [5] R. Borrego-Varillas et al., J. Am. Chem. Soc. 140, 16087 (2018).

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TitleDevelopment and Application of New NMR Methods for Studying Electrochemistry and Heterogeneous Catalysis
Speaker:Dr Evan Zhao Wenbo
Date:21 January 2021
Time:4.00pm to 5.00pm
Venue:Zoom (ID and PW will be given upon registration)
Host: Professor Atsushi Goto
Abstract: 

Nuclear magnetic resonance (NMR) is an extremely versatile spectroscopic technique with applications in chemistry, biology, physics and medicine. This talk will center around the development and applications of new NMR methods for studying flow electrochemistry and heterogeneous catalysis. In the first part, I will present new in situ NMR and electron paramagnetic resonance methods for studying organic molecule-based redox flow batteries, and discuss how these methods allow a large range of fundamental phenomena to be identified and quantified, including reaction intermediate and product, intermolecular electron transfer and electrolyte degradation.1,2 These fundamental insights motivate the development of methods to increase the lifetime and to measure the state of charge of redox flow batteries. In the second part of this talk, I will present the application of parahydrogen-induced hyperpolarization NMR in probing the pairwise addition of hydrogenation catalyzed by intermetallic nanoparticles, and discuss how parahydrogen can be used to enhance the NMR sensitivity by a factor of up to 1000.3,4

References 1. Zhao, E. W., Grey, C. P. et al. “In situ NMR metrology reveals reaction mechanisms in redox flow batteries” Nature 2020, 579, 224-228. 2. Zhao, E. W., Grey, C. P. et al. “Coupled in situ NMR and EPR studies reveal the electron transfer rate and electrolyte decomposition in redox flow batteries”. J. Am. Chem. Soc. In press. 3. Zhao, E. W., Huang, W., Bowers, C. R. et al. “Silica-encapsulated Pt-Sn intermetallic nanoparticles: a robust catalytic platform for parahydrogen-induced polarization of gases and liquids” Angew. Chem. Int. Ed. 2017, 56, 3925-3929. 4. Zhao, E. W., Huang, W., Bowers, C. R. et al. “Surface-mediated hyperpolarization of liquid water with parahydrogen” Chem 2018, 4, 1387-1403.

 

TitleUnravelling the Unique Microenvironment at Nanoparticle@MOF Interface and their Application in Gas-based Catalysis
Speaker:Dr Lee Hiang Kwee
Date:21 January 2021
Time:3.00pm to 4.00pm
Venue:Zoom (ID and PW will be given upon registration)
Host: Professor Atsushi Goto
Abstract: 

Gas reactions are prevalent in the industry and in our everyday lives. These processes typically require high temperature/pressure to boost gas concentration and energy for reaction activation. However, current practices are unsustainable because they are energy-intensive and potentially dangerous. Here, we achieve efficient gas-based reactions at remarkable ambient conditions by concentrating gas molecules at the interface formed between a functional solid and a metal-organic framework (MOF) with excellent gas sorptivitiy and selectivity. Using surface-enhanced Raman spectroscopy (SERS), we directly observe the accumulation of gas molecules into a quasi-condensed phase at the nanoscale solid@MOF interface, even at ambient operations. We further leverage on this pseudo high-pressure microenvironment to (1) activate the CO2 carboxylation of an arene that is otherwise inert at 1 atm and 298 K, and to (2) achieve efficient and selective electrochemical nitrogen-to-ammonia transformation. Our unique nanoparticle@MOF design thus offers enormous opportunities in relevant fields including heterogeneous catalysis, greenhouse gas removal and gas valorizations.

 

TitlePowering Selective Oxidations of Organic Molecules with Renewable Energy
Speaker:Dr Leow Wan Ru
Date:21 January 2021
Time:11.00am to 12.00pm
Venue:Zoom (ID and PW will be given upon registration)
Host: Professor Robin Chi
Abstract: 

The partial oxidation of organic molecules is an important class of reactions for the production of everyday commodities. An example is the polyethylene terephthalate (PET) plastic found in our drinking bottles – the precursors oxirane and terephthalic acid are produced from the partial oxidation of ethylene and xylene at 20 and 60 million tons per annum. Every year, 1.8 billion tons of CO2 are emitted due to the dependence of such partial oxidations on fossil-fuel-powered thermal control, as well as the tendency of these hydrocarbons tend to oxidize all the way to CO2.1 If we can develop high selectivity partial oxidations that are powered by renewable energy, we will be able to cut these associated CO2 emissions by half.2 In this talk, I will first discuss the activation of different functional groups on heterogeneous surfaces, to enable photocatalytic electron transfer under ambient and benign conditions.3-4 Key insights for rational surface engineering of heterogeneous photocatalytic materials to achieve partial oxidations for pharmaceuticals and fine chemicals will also be described. The second part will be focused on electrochemical partial oxidation at breakthrough current densities (1 A/cm2) by extending the reaction interface from the electrode surface with a charge mediator.5 These studies open opportunities for the development of alternative chemicals manufacturing routes towards a sustainable and decarbonized economy.

References 1. Boulamanti, A., Moya, J. A. Energy efficiency and GHG emissions: Prospective scenarios for the Chemical and Petrochemical Industry. 2017. 2. Zheng, J., Suh, S. Strategies to reduce the global carbon footprint of plastics. Nat. Clim. Change. 2019, 9 (5), 374-378. 3. Leow, W. R., Chen, X. et. al. Al2O3 surface complexation for photocatalytic organic transformations. J. Am. Chem. Soc. 2017, 139 (1), 269-276. 4. Leow, W. R., Chen, X. et. al. Correlating the surface basicity of metal oxides with photocatalytic hydroxylation of boronic acids to alcohols. Angew. Chem. Int. Ed. 2018, 57 (31), 9780-9784. 5. Leow, W. R., Lum, Y., Sargent, E. H. et. al. Selective ethylene oxide electrosynthesis at high current density enabled by a chloride mediator. Science, Accepted 2020.


 

TitleExcited State Dynamics in Nanoscale Materials for Renewable Energy: Time-domain ab initio Studies
Speaker:Dr Chu Weibin
Date:21 January 2021
Time:10.00 am to 11.00 am
Venue:Zoom (ID and PW will be given upon registration)
Host: Professor Robin Chi
Abstract: 

Understanding, predicting, and ultimately controlling excited carrier dynamics are at the heart of diverse chemistry, physics, and material science, such as solar energy conversion, photocatalysis, plasmonics, spin and valleytronics, to name a few. My research focuses on the first-principles study of far-from-equilibrium dynamics of charge carriers, as they couple with various quasiparticles in nanoscale, solid and molecular systems. The goal is to understand the behavior of electrons in multidimensions, including time, energy, real and momentum spaces. In this talk, I will review several of my developments for nonadiabatic molecular dynamics and time-domain density functional theory, which are popular, versatile, and powerful tools to study such real-time dynamics of excited carriers in nanoscale systems. Recent experimental advances in photocatalysis and solar cells create a rare opportunity for the application of these theoretical developments. Each methodological advance will be exemplified with a specific application in an emerging material in those fields as shown below.

References (1) Chu, W.; Zheng, Q.; Prezhdo, O.V.; Zhao, J.* J. Am. Chem. Soc., 2020, 142,3214. (2) Dereka, B.; Yu, Q.; Lewis, N.H.; Carpenter, W.B.; Bowman, J.M.; Tokmakoff, A., Science, 2021. 371, 160. (3) Chu, W.; Zheng, Q.; Feng, Y.; Prezhdo, O.V.; Li, X.*; Zhao, J.* To be submitted. (4) Chu, W.; Zheng, Q.; Prezhdo, O.V.; Zhao, J.*; Saidi, W.A.* Sci. Adv., 2020, 6, eaaw7453. (5) Chu, W.; Saidi, W.A; Zhao, J.; Prezhdo, O.V.* Angew. Chem. Int. Ed., 2020, 59, 6435.

 

TitleIon Mobility Collision Cross-Section Atlas for Known and Unknown Metabolite Annotation in Untargeted Metabolomics
Speaker:Professor Zhu Zheng-Jiang
Date:15 January 2021
Time:2.00 pm to 3.30 pm
Venue:Zoom (ID and PW will be given upon registration)
Host: Assistant Professor Qiao Yuan
Abstract: 

The metabolome includes not just known but also unknown metabolites; however, metabolite annotation remains the bottleneck in untargeted metabolomics. Ion mobility – mass spectrometry (IM-MS) has emerged as a promising technology by providing multi-dimensional characterizations of metabolites. Recently, we curated an ion mobility CCS atlas, namely AllCCS, and developed an integrated strategy for metabolite annotation using known or unknown chemical structures. The AllCCS atlas covers vast chemical structures with >5000 experimental CCS records and ~12 million calculated CCS values for >1.6 million small molecules. We demonstrated the high accuracy and wide applicability of AllCCS with medium relative errors of 0.5-2% for a broad spectrum of small molecules. AllCCS combined with in-silico MS/MS spectra facilitated multi-dimensional match and substantially improved the accuracy and coverage of both known and unknown metabolite annotation from biological samples. Together, AllCCS is a versatile resource that enables confident metabolite annotation, revealing comprehensive chemical and metabolic insights towards biological processes.

 

TitleDesign of Chiral Catalysts for Enantioselective C-H Functionlization 
Speaker:Professor Shigeki Matsunaga
Date:8 January 2021
Time:3.00pm to 4.30pm
Venue:Zoom (ID and PW will be given upon registration)
Host: Associate Professor Naohiko Yoshikai 
Abstract: 

Our research group is interested in the development of new catalysts/molecules to streamline organic synthesis. Among ongoing projects in our group,1-4 the development of new chiral catalysts for enantioselective C-H functionalization will be discussed in this lecture. 

As a part of our ongoing projects on C-H functionalization,1 we demonstrated the power of chiral sulfonic acid/carboxylic acid-assisted enantioinduction with readily available achiral Cp*Rh(III)/Co(III)-catalysts. Cp*Rh(III) complexes combined with chiral counterion such as a binaphthyl-based sulfonate (BINSate) and a chiral spiro sulfonate (SPISate)2a were effective in enantioinduction after C-H activation. Asymmetric induction at the C-H bond activation step was also achieved with combined use of Cp*Rh(III)/Co(III) and chiral carboxylic acids, giving nitrogen containing chiral building blocks in up to 98.5:1.5 er.2b Further studies to expand the library of effective chiral acids for C-H functionalization in combination with CpxRh(III)/Co(III) complexes2c,2d as well as some other related projects on a chiral paddle-wheel dinuclear Ru catalysts3a and a dinuclear Cu/Pd Schiff base complex3b will be introduced.