Exploiting Controlled Reaction-Diffusion Conditions for the Engineering of Functional Matter

Josep Puigmartí-Luis^1,2

¹University of Barcelona, Spain
²ICREA, Spain

Self-assembly has long being used to control covalent and non-covalent interactions where molecular design has been the major driving force to achieve a desired outcome. Like in nature, a full control over self-assembly processes could lead to rationalized structure-property correlations, a long-time sought in chemistry, physics and materials science. However, the pathways followed and the mechanisms underlying the formation of supramolecular aggregates are still largely unknown and unresolved. Accordingly, the elucidation of nucleation and growth mechanisms will be highly required to push supramolecular chemistry to the next level, where access to nature inspired functions will be accomplished. In this contribution, I will present how reaction-diffusion (RD) conditions established within microfluidic devices can be used to uncover pathway complexity as well as to trigger pathway selection. Specifically, I will show that microfluidic RD conditions provide an unprecedented kinetic control over self-assembly processes; for example, enabling the isolation of well-defined kinetically trapped states as well as unprecedented metastable intermediates. This research provides a new tool to study and understand supramolecular chemistry and opens up new avenues for the engineering of advanced functional assemblies and systems.

Biography:
Josep Puigmartí-Luis is a chemist who completed a master in Chemistry and Food Engineering at “Institut Químico de Serrià (IQS)” (2003) and did a PhD in materials science at Institut de Ciència de Materials de Barcelona (ICMAB). His work in supramolecular and flow chemistry, has been awarded with “Premi Antoni de Martí i Franquès de Ciències Químiques”, award from the Institut d’Estudis Catalans (2009), St. Jordi award from the Institut d’Estudis Catalans and the Societat Catalana de Química (2006) and an ETH fellowship in 2008. In 2012, he was appointed as Ramon Y Cajal (RyC) researcher, but after two years as a RyC, he decided to move back to Switzerland where in 2015 was awarded an ERC starting grant to study and control self-assembly processes of metal-organic based crystalline materials. In 2019, he was appointed as an ICREA Research Professor and since 2020, his group is located at the University of Barcelona (UB). His research interests include the synthesis and controlled design of functional materials in solution and on surfaces, as well as the development of microfluidic technologies to command and understand the formation and function of unprecedented out-of-equilibrium assemblies (a key aspect to unveil structure-properties correlations of new functional matter).

Nanostructured Electrocatalysts for CO₂ Valorization to Added Value Products

Simelys Hernández^*, Hilmar Guzmán and Nunzio Russo

Polytechnic University of Turin, Italy

Greenhouse Gases emission control is one of the most challenging environmental issues to face in the 21st century. The electrocatalytic CO₂ reduction driven by renewable energy sources can be used to store both renewable electricity and CO₂ in valuable products such as syngas, organic acids (like formic acid) and/or liquid fuels (methanol or > C₁ products with a higher energy density) [1]. The main challenge is to find a suitable electrocatalyst to establish this technology at industrial level. For the syngas (CO and H₂ mixtures) production, the most commonly used catalyst is based on noble metals like silver (Ag) and gold (Au) [2]. In our group, we have developed a low-cost Agbased catalyst by dispersing Ag nanoparticles in the top of TiO₂ nanotubes (NTs) [3], showing a higher electrochemical surface area and electrons transport than bare Ag foil and Ag on TiO₂ nanoparticle. TiO₂ was used as an efficient support for metal catalysts, which enhances the stability of key CO₂.^- radical intermediate formation and decreases the CO₂ electroreduction overpotential. Moreover, we are exploiting the current knowledge of the thermocatalytic CO₂ hydrogenation to develop an optimal electrocatalyst for the CO₂ electrochemical reduction. When Cu/Zn/Al-based catalysts are tested for these two processes different products are obtained at the respective optimum operative conditions (i.e. high H₂ partial pressure (P) and temperature (T) > 200°C for the thermocatalytic CO₂ reduction, while atmospheric T and P are used in the electrocatalytic one). While the thermocatalytic process induces the production of methanol and CO, the electrocatalytic one generates H₂, CO as well as other C-containing liquid products (from C₁ to C₃). We have developed low-cost nanostructures catalysts able to produce syngas with a tunable composition (depending on the applied potential) and other liquid C₂⁺ products through the electrochemical CO₂ reduction at ambient T,P. These results pave the way to the implementation of novel nanostructured materials towards the development of a highly sustainable and economic technology for the CO₂ conversion to the fuels of the future.

Biography:
Simelys Hernández had a PhD in Chemical Engineering from Politecnico di Torino (Polito), Italy. She is an Associate Professor of Chemical Plants and responsible of the “CO₂ reduction for a low-carbon economy team” at CREST group, DISAT - Polito. She is technical coordinator of the EU H2020 projects SunCOChem, CELBICON and RECODE focused on CO₂ capture (from atmosphere or flue-gases) and its conversion to valuable chemicals, fuels and biopolymers. She is author of >80 papers in ISI journals, including book chapters. Her H-index is 27. She is among the TOP 2% scientists in the Applied Science – Engineering field and is a repute member of editorial and reviewer boards of top journals (e.g. Nature Catalysis).

References:
1. H. Guzmán, et. al. Photo/electrocatalytic hydrogen exploitation for solar fuels production, Chapter 11 in: Handbook of Hydrogen Production from Solar Energy, Elsevier.
2. S. Hernández, et. al. Green Chem., 2017, 19, 2326 2346.
3. M. Amin Farkhondehfal, et. al. Int . J. Hydrogen Energy, 2019 , 45 (50), 26458-26471.

Theoretical Insight on CO₂ Hydrogenation over Small SnO₂ Clusters

Ramesh Chandra Deka^* and Plaban J. Sarma

Tezpur University, India

Global optimisation of (SnO₂)n clusters in the range of n=1-20 is performed by employing genetic algorithm implemented in Knowledge Led Master Code (KLMC) software suite. For each cluster size, prescreening of each cluster size are done with interatomic potential followed by density functional theory geometry optimisation for a reasonable numbers of conformers. By analyzing different stability criteria, such as binding energy per atom, second difference in energy, the lowest energy structures were determined. From the second order energy differences of the global minima, n =10 is found to be the most stable cluster. The optical properties of the clusters were correlated with the calculated HOMO-LUMO energy gap of the global minima clusters. Furthermore, mechanism of hydrogenation of CO₂ to formic acid over SnO₂ monomeric and dimeric structures as catalysts shows a new route for the formation of formic acid via ‘Hydride Pinning Pathway’. This mechanism provides a unique selectivity for HCOOH through hydride transfer step over CO formation and H₂ recombination reaction at lower overpotential. We consider that the enhanced activity of SnO₂ clusters for CO₂ conversion would help in designing efficient catalysts for experimental studies. We also investigated the influence of titanium dopant on Sn₂O₄ cluster for H₂dissociation on the doped systems and then the subsequent mechanism for the conversion of CO₂ into formic acid (FA) via a hydride pinning pathway. The lowest barrier height for H₂ dissociation is observed across the ‘Ti-O’ bond of the Ti-doped Sn₂O₄ cluster, with a negatively charged hydride (Ti-H) formed during the heterolytic H₂ dissociation, bringing selectivity towards the desired FA product. The formation of a formate intermediate is identified as the rate determining step (RDS) for the whole pathway, but the barrier height is substantially reduced for the Ti-doped system when compared to the same steps on the undoped Sn₂O₄cluster.

Biography:
Ramesh Chandra Deka completed his Ph. D. from National Chemical Laboratory, 1998, Post-doc at Tokyo University from 1999-2001, AvH post-doc at Technical University of Munich, Germany from 2003-2004. He is a Lecturer in Tezpur University from 2001-2004, Reader in Tezpur University from 2004-2006, Associate Professor in Tezpur University from 2006-2010, Professor in Tezpur University from 2010 to till date. He has Publications of about 200.
Awards: Secretary of Catalysis Society of India 2018; Professor A. S. R. Anjaneyulu Endowment Award, 2017 by the Indian Chemical Society; Fellow of the Royal Society of Chemistry (FRSC) 2017; Bronze Medal, Chemical Research Society of India (CRSI) 2013; Professor H. C. Goswami award by Assam Science Society, 2013.

Sensor, Photocatalysis and Anti-Bacterial Applications of Novel Metal/Metal Oxide Nanocomposites

Md Abdus Subhan

Shah Jalal University of Science and Technology, Bangladesh

Metal/metal oxide nanocomposites are being extensively studied as a potential sensor, catalysis and anti-bacterial agent. The activity of nanomaterial changes with several factors including size, morphologies and crystal growing. ^1,2 The self-assembled nanostructured materials (including Ag•NiMn₂O₄and Ag•SrSnO₃ NRs) are promising sensor, photocatalyst and anti-bacterial agent against MDR bacteria.^1-5 These materials have been used for the fabrication of sensor probe for the detection and quantification of the environmental toxins (e.g., phenylhydrazine, bis-phenol A) in a very small quantity (nM-pM) level. These oxides have been promising for degrading dyes efficiently in waste water. The metal/metal oxide nanomaterials have been applied for studying anti-bacterial activity against pathogenic bacteria including both Gram positive and Gram negative one, in presence and absence of light and compared with the standard antibiotic. The metal oxide nanocomposites are effective against multi-drug resistant (MDR) bacteria both in presence and absence of light. The excitation of the nanocomposite by light and formation of the radicals like reactive oxygen species (ROS) prompted bacteria killing through the ROS mechanism. The minimum inhibitory concentration (MIC) is defined as the lowest concentration of a compound that will completely inhibit the visible growth of microorganisms after overnight incubation. Minimum Bactericidal Concentration (MBC) is the lowest concentration of an anti-bacterial agent required to kill a bacterium under a certain set of conditions over a specified, quite prolonged period of time, such as 18 hours or 24 hours. The MIC and MBC of the nanocomposite against MDR bacteria have been evaluated to identify the minimum effective dose required. The self-assembled nanostructured are auspicioussensor, catalyst and anti-bacterial agent against MDR bacteria as well as an industrial sterilization system.^1-5

Biography:
Md Abdus Subhan received his PhD from Osaka University, with Japanes Government Monbusho Scholarship (Recommended by Bangladesh Government). Currently he is a Professor at Shah Jalal University of Science and Technology, Sylhet, Bangladesh. He held several postdoctoral positions in different countries including VBL (venture business laboratory) fellowship in Materials and Life Science, Faculty of Engineering, Osaka University, Japan; BK 21 postdoc fellowship in Seoul National University and NRF (National Research Foundation, South Korea) postdoc fellowship Andong National University, South Korea and Fulbright Visiting Scholar fellowship in Northeastern University, Boston, MA, USA. His current research field is nanomaterials, nanomedicine and drug delivery. He has a great contribution in sensor, catalytic, optical and drug delivery research using nanomaterials, which is reflected in his published papers in recent years. He has published 66 papers with many appearing in the high-impact journals. He has strong track record (h-index 15, i10 index 28).

References:
1. Subhan, M. A. et al., (2019). New J. Chem.,43, 10352.
2. Subhan, M. A. et al., (2020). Journal of Environmental Chemical Engineering, 8, 104051.
3. Subhan, M. A. et al., (2020). RSC Advances, 10(19), 11274-11291.
4. Subhan, M. A., et al., (2018), New J. Chem.,42, 872.
5. Subhan, M. A., et al., (2021), New J. Chem.,Advance article. https://doi.org/10.1039/D0NJ04813E.

Optimizing Deposition of Platinum Nanoparticles on Functionalized Graphene Oxide

Nur Uddin Ahamad^1*, Howard Fairbrother², Benjamin P. Frank³ and Leslie Sigmon⁴

¹Shahjalal University of Science and Technology, Bangladesh
^2,3,4Johns Hopkins University, USA

In this research, we explored different parameters for depositing platinum nanoparticles on sulfonated graphene oxide (S-GO). Platinum nanoparticles (NPs) were formed in situ by reduction of a platinum precursor with sodium borohydride in presence of S-GO matrix. Prior to the deposition, GO was functionalized with sulphonic acid groups using a method developed in Professor Howard Fairbrother’s research laboratory to improve the colloidal stability of GO in aqueous medium. The deposition process was optimized by varying the ratio of platinum precursor to S-GO (mass). The deposition was found to rely on the ratio of platinum cations to NaBH₄ (mole) as well as the reaction temperature and time. Chemical changes in GO due to reduction were followed with Fourier-transform Infrared Spectra (FT-IR) while elemental analysis was carried out by X-ray Photoelectron Spectroscopic technique (XPS) and size and shape of the platinum NPs was confirmed by analyzing Transmission Electron Microscopic (TEM) image.

Biography:
Nur U. Ahamad is a Professor of Chemistry at Shahjalal University of Science and Technology (SUST) in Bangladesh. He received his BSc and MSc in Chemistry from SUST where he started his career as a lecturer in 2004. He had been in Canada from 2006 to 2012 to complete his PhD from the Department of Chemistry at Carleton University in Ottawa. His PhD thesis focused on fabrication of 2D assemblies of metal nanostructures, with optimized size, shape and composition, as a platform for plasmonic sensors. After completion of his PhD he moved back to his home country to establish his own research lab. He received several research projects funded by national funding agencies like SUST-research center, UGC, Ministry of Education, Ministry of Science and Technology. As a potential young researcher, he was awarded a fellowship to attend the JSPS-HOPE Meeting with Nobel Laureates in 2016 in Japan. In the same year, he achieved Fulbright Visiting Scholar Grantto work in the Department of Chemistry at Johns Hopkins University, USA. There, he worked with Professor Howard D. Fairbrotheron fabricating environmentally benign fire-retardant textiles. His active field of research involve innovation of smart textile products, modification of nanocellulose for biomedical application and synthesis of inorganic nanostructures for environmental remediation and energy production. Dr. Ahamad is associated with several scientific organizations like American Chemical Society, Canadian Society for Chemistry, Bangladesh Chemical Society, JSPS-HOPE and Fulbright Associations. He is also a reviewer of the Journal of Plasmonics.