People in this Project: Markus Snellman, Irene Bechis, Joao Freitas, Tiago Rebelo, E.A. Anumol, Junjie Li and Francis Leonard Deepak

Monometallic, Bimetallic and multimetallic core-shell nanoparticle/nanowire catalysts of noble metal alloys possesses superior activity, high selectivity and stability at low temperature compared to traditional bulk metals. This makes them ideal candidates for carrying out investigations on their structure, nature of alloy formation and thus understand the way the catalytic activity is enhanced. Direct microscopic studies of various bimetallic nanoparticles have been carried out using high-resolution transmission electron microscopy (HRTEM). However, this method is limited because of the small difference in the lattice constant involved. Conventional transmission electron microscopy (CTEM) can produce chemical contrast due to due to different electron beam extinction distances. This has been applied successfully to image bimetallic nanoparticles down to 10 nm in diameter. Since the particles need to be in a low index zone orientation, this method is not easy to use in practice. As an alternative method of nanostructure determination high angle angular dark field (HAADF) imaging technique has been used successfully. The HAADF method has been used to detect variation in chemical composition down to single atom level in structures of nanosized particles. STEM-HAADF imaging carried out in an aberration corrected microscope reveals the atomistic structure and the alloying of bimetallic nanoparticles and nanowires. In combination with high resolution spectral and chemical analysis this techniques provides unprecedented information never obtained till date. Understanding the nature and structure of such bimetallic/multimetallic nanocatalysts is important to enable modification of their structure/morphology/composition and enhance their catalytic performance for fuel cells and other industrial applications.

External Collaborations

Prof. M. Arturo López-Quintela (Dept. Physical Chemistry, Faculty of Chemistry Lab of Nanotechnology and Magnetism (NANOMAG) Research Technological Institute University of Santiago de Compostela)

Dr. P. John Thomas (School of Chemistry, Bangor University, Bangor, UK)

Prof. Maurizio Muniz-Miranda (“Ugo Schiff” Chemistry Dept, University of Florence)

Dr. Roberto Pilot (Consorzio INSTM and Department of Chemical Sciences, via Marzolo 1, 35131 Padova, Italy)

Dr. C.P. Vinod (Catalysis Division and Center of Excellence on Surface Science, CSIR National Chemical Laboratory, Pune, INDIA)

Dr. R. Nandini Devi (Catalysis Division, National Chemical Laboratory, Pune, India)

Dr. Qiang Li (School of Mechanical Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China)

Dr. Deqiang Yin (School of Mechanical Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China and Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan)

T. Del Rosso, Department of Physics, Pontifi­cia Universidade Catolica do Rio de Janeiro, Brazil

Book Chapters

• Loukya Boddapati and Francis Leonard Deepak, Scanning Transmission Electron Microscopy of Magnetic Nanoalloys and their Nanocomposites, In: Thomas S., Rezazadeh Nochehdehi A. (eds) Handbook of Magnetic Hybrid Nanoalloys and their Nanocomposites. Springer, Cham. doi.org/10.1007/978-3-030-34007-0_39-1, 2022.
• Advanced Electron Microscopy Techniques Towards the Understanding of Metal Nanoparticles and Clusters, Francis Leonard Deepak, E.A. Anumol, Junjie Li, Book: Metal Nanoparticles and Clusters: Recent Advances in the synthesis, properties and applications (Springer), Ed: Francis Leonard Deepak (2018).
• Advanced Methods of Electron Microscopy in Catalysis Research, Miguel Jose-Yacaman, Arturo Ponce-Pedraza, Sergio Mejia-Rosales and Francis Leonard Deepak, Advances in Imaging & Electron Physics (Academic Press), Editor: Peter Hawkes, vol. 177, pp: 279-342 (2013).

Edited Book

Metal Nanoparticles and Clusters Advances in Synthesis, Properties and Applications, Ed: Francis Leonard Deepak, Springer 2018.

Publications

(1) Boosting acidic water oxidation performance by constructing arrays-like Nanoporous IrxRu1−xO2 with abundant atomic steps, Junjie Li, Zan Lian, Qiang Li, Zhongchang Wang, Lifeng Liu, Francis Leonard Deepak, Yanping Liu, Bo Li, Junyuan Xu and Zuxin Chen, Nano Research, 2022, 15, 5933-5939.

(2) Catalysis of ceria incorporated magnesium hydride: A follow up study, D. Pukazhselvan, Ihsan Çaha, Suresh Kumar Jakka, Vanessa C. D. Graça, Laura I. V. Holz, M.J. Soares, Andrei V Kovalevsky, Francis Leonard Deepak, Duncan Paul Fagg, International Journal of Hydrogen Energy, 2022, 47, 28978-28992.

(3) Sustainable Existence of Solid Mercury (Hg) Nanoparticles at Room Temperature and Their Applications, Krishna Harika Villa, Tirupathi Rao Penki, Loukya Boddapati, Atanu Samanta, Gui-Liang Xu, Chengjun Sun, Ilya Grinberg, Francis Leonard Deepak, Khalil Amine, Doron Aurbach and Aharon Gedanken, Chem. Sci., 2021, 12, 3226-3238.

(4) Selectivity boost in partial hydrogenation of acetylene via atomic dispersion of platinum over ceria, Olumide Bolarinwa Ayodele, Simone Vinati, Emanuele Barborini, Loukya Boddapati, Khalil El Hajraoui, Jutta Kröhnert, Francis Leonard Deepak, Annette Trunschke and Yury V. Kolen’ko, Catal. Sci. Technol., 2020, 10, 7471-7475.

(5) A one-pot route to stable Pickering emulsions featuring nanocrystalline Ag and Au, Oliver L. Armstrong, Sean N. Baxter, F. L. Deepak and P. John Thomas, Chem Comm, 2020, 56, 4801-4803.

(6) Ultrafine-Grained Porous Ir-Based Catalysts for High Performance Overall Water Splitting in Acidic Media, Junjie Li, Junyuan Xu, Qiang Li, Nan Zhang, Yunping Li, Lifeng Liu, Zhongchang Wang and Francis Leonard Deepak, ACS Appl. Energy Mater. 2020, 3, 4, 3736–3744.

(7) Large-scale fabrication of hollow Pt₃Al Nanoboxes and their electrocatalytic performance for hydrogen evolution reaction, Qiang Li, Bin Wei, Yue Li, Junyuan Xu, Junjie Li, Lifeng Liu and Francis Leonard Deepak, ACS Sustainable Chemistry & Engineering, 2019, 7, 11, 9842-9847.

(8) Biocompatible Au@Carbynoid/Pluronic-F127 nanocomposites synthesized by pulsed laser ablation assisted CO₂ recycling, T. Del Rosso, S.R.W. Louro, F.L. Deepak, E.C. Romani, Q. Zaman, Tahir, O. Pandoli, M. Cremona, F.L. Freire Junior, P. De Buele, T. De St. Pierre, R.Q. Aucelio, G. Mariotto, S. Gemini- Piperni, A.R. Ribeiro, S.M. Landi, A. Magalhaes, Appl. Surf. Sci., 2018, 441, 347-355.

(9) Qiang Li, Deqiang, Yin, Junjie Li, and Francis Leonard Deepak, Atomic-Scale Understanding of Gold Cluster Growth on Different Substrates and Adsorption-Induced Structural Change, J. Phys. Chem. C 2018, 122, 1753-1760.

(10) Magnetic Nanoparticles obtained by two-step Laser Ablation of Nickel and Silver in pure Water, Cristina Gellini, Francis Leonard Deepak, Maurizio Muniz-Miranda, Stefano Caporali, Francesco Muniz-Miranda, Alfonso Pedone, Claudia Innocenti, Claudio Sangregorio, J. Phys. Chem. C 2017, 121, 3597-3606.

(11) A convenient route for Au@Ti-SiO₂ nanocatalyst synthesis and its application for room temperature CO oxidation, Yogita Sonia, A. Anumol, Chandrani Nayak, Francis Leonard Deepak, C.P. Vinod, J. Phys. Chem. C 2017, 129, 4946-4957.

(12) Understanding alloy structure and composition in sinter-resistant AgPd@SiO₂ encapsulated catalysts and their effect on catalytic properties, Sourik Mondal, Thattarathody Rajesh, Basab B. Dhar, Markus Snellman, Junjie Li, Francis Leonard Deepak and R. Nandini Devi, New J. Chem., 2017, 41, 14652.

(13) Controlling Bimetallic Nanostructures by the Microemulsion Method with Subnanometer Resolution Using a Prediction Model, David Buceta, Concha Tojo, Miomir Vukmirovic, Francis Leonard Deepak, Arturo M. Lopez-Quintela, Langmuir, 2015, 31, 7435-7439.

(14) Wavelength dispersion of the local field intensity in silver–gold nanocages, R. Pilot, Zoppi, S. Trigari, F. L. Deepak, E. Giorgetti and R. Bozio, Phys. Chem. Chem. Phys., 2015, 17, 7355.

(15) Stable Ruthenium colloids by Laser Ablation, Brandi, S. Caporali, S. Cicchi, L. Lascialfari, M. Muniz-Miranda, S. Orazzini, M. Severi, Francis Leonard Deepak and E. Giorgetti, IEEE NANO, July 2015.

People in this Project:  Sabyasachi Saha, Rong Sun, Loukya Boddapati, Junjie Li and Francis Leonard Deepak

Doping is an effective method to tune the electronic properties for MoS₂ as well as other 2D semiconductors and has significant implications on their optical and electronic properties. In this project we fabricate doped MoS₂ samples with different dopants and/or doping concentrations and study them employing high resolution imaging and spectroscopy.

Publications  

Direct observation of intrinsic twisted stacking domains in the van der Waals magnet CrI3, Myeongjin Jang, Sol Lee, Fernando Cantos-Prieto, Ivona Košić, Jong Chan Kim, Jun-Yeong Yoon, Loukya Boddapati, Francis Leonard Deepak, Hu Young Jeong, Elton J.G. Santos, Efrén Navarro-Moratalla, Kwanpyo Kim, Submitted 2022.

Atomic Metal-Semiconductor Interfaces in Tin-Intercalated MoS2, Avraham Twitto, Chen Stern, Michal Poplinger, Ilana Perelshtein, Sabyasachi Saha, Akash Jain, Kristie J. Koski, Francis Leonard Deepak, Ashwin Ramasubramaniam, and Doron Naveh, Submitted 2022.

Functionalized magnetic composite nano/microfibres with highly oriented van der Waals CrI₃ inclusions by electrospinning, Vahideh Bayzi Isfahani, Joao Filipe Horta Belo da Silva, Loukya Boddapati, Anabela Gomes Rolo, Rosa Batista, Francis L. Deepak, Joao Pedro Araujo, Etelvina de Matos Gomes and Bernardo G Almeida, Nanotechnology, 2021, 32, 145703.

Enhancing Light-Matter Interactions in MoS2 by Copper Intercalation, Chen Stern, Avraham Twitto, Rafael Snitkoff, Yafit Pleger, Sabyasachi Saha, Loukya Boddapati, Akash Jain, Mengjing Wang, Kristie J. Koski, Francis Leonard Deepak, Ashwin Ramasubramaniam and Doron Naveh, Adv. Mater., 2021, 33, 2008779.

Extrinsic Room Temperature Ferromagnetism in MoS₂, Sabyasachi Saha, Manuel Bañobre-López, Oleksandr Bondarchuk, Joaquín Fernández-Rossier, Francis Leonard Deepak, J. Mat. Sci., 2021, 56, 9692-9701.

Engineering Surface Electron and Active Site at Electrochemical Sensing Interface of CN Vacancy-Mediated Prussian Blue Analogue for Analysis of Heavy Metal Ions, Wen-Yi Zhou, Rong Sun, Shan-Shan Li, Yuzheng Guo, Wei Shen, Jun Wang, Francis Leonard Deepak, Ying Li and Zhongchang Wang, Appl. Surf. Sci. 2021, 564, 150131.

Morphology-Tunable Synthesis of Intrinsic Room-Temperature Ferromagnetic γ-Fe2O3 Nanoflakes, Zhiyan Jia, Wenjie Wang, Zichao Li, Rong Sun, Shengqiang Zhou, Francis Leonard Deepak, Chenliang Su, Ying Li and Zhongchang Wang, ACS Appl. Mater. Interfaces, 2021, 13, 24051-24061.

G. Deokar, Nitul S. Rajput, J. J. Li, F. L. Deepak, W. Ou-Yang, N. Reckinger, C. Bittencourt, J.-F. Colomer, M. Jouaid, Toward the use of CVD-grown MoS₂ nanosheets as field-emission source, Beilstein J. of Nanotechnology, 2018, 9, 1686-1694.

FCT-UT Austin Funded Project: Two dimensional magnetic semiconductors (2DMS)

Period: 01-09-2018 to 31-08-2020

Funding: Euro 99.450,00

Electrical Characterization of CIGSe Solar Cells

People in this Project: Ihsan Çaha, Khalil El Hajraoui, Mario Villa Navas and Francis Leonard Deepak

The project “Correlated Analysis of Inorganic Solar Cells in and outside an electron microscope” aims to fabricate in-situ TEM cartridges for carrying out electrical measurements of CIGS solar cells. These chips will be universally adaptable, provide flexibility and significant advantages to the existing ones and will enable simultaneous experimentation both inside and outside the TEM. Subsequent to their fabrication they will be employed to the study of a solar cell device (CIGS) under near-operating conditions, providing unprecedented insight into relevant processes at grain boundaries and interfaces by using correlated multi-scale analysis with resolutions ranging from the atom to the entire device.

FCT Funded Project: Correlated Analysis of Inorganic Solar Cells in and outside an Electron Microscope (CASOLEM).

Period: 26-07-2018 to 25-07-2022
Funding Program: FCT and the ERDF through COMPETE2020 (National Project)
Funding: Euro 239.474,83

Collaborations: Nanostructured Solar Cells Group (INL) and Laboratory For Carbon Nanostructures Group (KAUST, Saudi Arabia)

Publications

SiOx patterned based substrates implemented in Cu(In,Ga)Se2 ultrathin solar cells: optimum thickness, Kevin Oliveira, Jennifer P. Teixeira, Wei-Chao Chen, Jackson Lontchi, António J. N. Oliveira, Ihsan Çaha, Francis Leonard Deepak, Denis Flandre, Marika Edoff, Paulo A. Fernandes, Pedro M. P.Salomé, IEEE Journal of Photovoltaics, 2022, 12, 954-961.

Cu(In,Ga)Se2 based ultrathin solar cells the pathway from lab rigid to large scale flexible technology, T.S. Lopes, J.P. Teixeira, M.A. Curado, B.R. Ferreira, A.J.N. Oliveira, J.M.V. Cunha, M. Monteiro, A. Violas, K. Oliveira, J.R.S. Barbosa, P.C. Sousa, I. Çaha, J. Borme, J. Ring, W.C. Chen, Y. Zhou, K. Takei, E. Niemi, F.L. Deepak, M. Edoff, G. Brammertz, P.A. Fernandes, B. Vermang, P.M.P. Salomé, Submitted 2022.

Micro‑sized thin‑film solar cells via area‑selective electrochemical deposition for concentrator photovoltaics application, Daniel Siopa, Khalil El Hajraoui, Sara Tombolato, Finn Babbe, Alberto Lomuscio, Max H. Wolter, Pedro Anacleto, Kamal Abderrafi, Francis L. Deepak, Sascha Sadewasser and Phillip J. Dale, Scientific Reports 2020, 10, 14763 (1-13).

Atomic-scale interface modification improving the performance of Cu(In1- xGax)Se2/Zn(O,S) heterojunction solar cells, Khalil El hajraoui, Diego Colombara, José Virtuoso, Ralf Waechter, Francis Leonard Deepak, Sascha Sadewasser, ACS Appl. Mater. Interfaces 2021, 13, 37, 44207–44213

Nucleation, Growth, Dynamics and Phase Transformations

People in this Project: Junjie Li and Francis Leonard Deepak

In-Situ Generation of Sub-10 nm Silver Nanowires under electron beam irradiation in the TEM

Sub-10 nm quasi-one dimensional (1D) nanostructures have received increasing interest for their use as small basic building units in nanodevices. One dimensional Silver (Ag) nanostructures, as one of the promising candidates for electronics, plasmonics and sensing applications, have been fabricated by a variety of chemical and physical strategies. However, preparing sub-10 nm (diameter) 1D Ag nanostructures remains challenging experimentally and the nucleation and growth dynamics of the Ag nanowires are still not fully understood.

In this study it was revealed for the first time that by controlling the electron irradiation dose rates, sub-10 nm Ag NWs can be fabricated on an oxide surface. Further the diameter of the formed Ag nanowires can be precisely manipulated by the electron beam irradiation doses. The nucleation and growth dynamics of the Ag nanowires were also uncovered in the TEM in this study.

The ability to fabricate Ag NWs in a controllable way by using electron beam irradiation represents a significant step forward to the further applications of Ag NWs in nanodevices. The present study opens a new avenue for the fabrication of supported sub-10 nm Ag nanowires through an electron beam irradiation nanofabrication route and highlights the importance of irradiation dose- and dynamics controlled materials growth.

Atomic Scale dynamic observation reveals temperature-dependent multi-step nucleation pathways in crystallization

Uncovering kinetic pathways of non-classical multistep nucleation at the atomic scale is critical to understanding complex microscopic mechanisms of heterogeneous nucleation and crystallization. However, due to the intricacies in tackling such challenging topics experimentally, the structure of intermediate states and the effect of temperature on multistep nucleation at the atomic scale are still not fully understood.

In this study direct in-situ atomic-scale observations of kinetic processes of interfacial multistep nucleation pathways at the atomic scale using an aberration-corrected transmission electron microscope was revealed. Direct evidence to temperature-dependent multistep nucleation pathways in a supported bismuth system at the atomic scale is provided.

This study highlights the importance of temperature on heterogeneous nucleation and crystallization dynamics, which advances our understanding of non-classical multistep heterogeneous nucleation and helps to clarify the atomic origin of temperature effected behaviour in nanomaterials and hetero-structures.

In Situ Atomic-Scale Study provides insights into sublimation dynamics at the atomic scale

The process by which a crystal sublimates into a gas is a first-order phase transition of considerable fundamental and practical importance in condensed matter physics, material science, and climate change, yet a detailed understanding of its relevant kinetic pathways is still evolving even for model systems whose equilibrium configuration is known in advance.

For over a century, scientists have speculated on how ice sublimates and which key factors (e.g., particle size, morphology, defects) influence sublimation.

However many critical details such as structural evolution, dynamic processes, sublimation mechanism and role of defects in sublimation remain neither fully understood nor clearly established at the atomic scale.

In this study direct in-situ atomic scale observations were carried out to reveal the effect of size, surface and defects on the uniform and non-uniform sublimation pathways of Silver nanocrystals (which is used as a model system) under heating within an aberration -corrected Transmission electron microscope.

The ability to conduct in situ atomic-scale observation of kinetic pathways of sublimation in nanomaterials represents a significant step forward in understanding atomic mechanisms of the solid-gas phase transitions. The findings in the present study demonstrate that the size, shape and defects are of paramount importance for the sublimation dynamics in the first-order phase transformation, helping to advance our general understanding of many technological applications including sublimation-based purification, thin film deposition, and fabrication of nanoparticles.

In situ observation of the lattice induced growth of nanocrystals on substrate

Uncovering dynamical processes of lattice induced epitaxial growth of nanocrystal on the support is critical to understanding crystallization, solid-phase epitaxial growth, Oswald ripening process, and advanced nanofabrication, all of which are linked to different important applications in material field. Here, we conduct direct in-situ atomic-scale dynamical observation of segregated Bi layers on SrBi₂Ta₂O₉ support under low dose electron irradiation to explore the nucleation and growth from an initial disordered solid state to a stable faceted crystal by using aberration corrected transmission electron microscopy (AC-TEM). We have provided, for the first time, atomic-scale insights into the initial pre-nucleation stage of lattice induced interfacial nucleation, size-dependent crystalline fluctuation and stepped growth stage of the formed nanocrystal on the oxide support at the atomic scale. We identify a critical diameter in forming a stable faceted configuration and find interestingly that the stable nanocrystal presents a size-dependent coalescence mechanism. These results offer an atomic-scale view into dynamic process at solid/solid interfaces, which has implications for thin film growth and advanced nanofabrication.

In situ observation of Droplets Coalescence Driven Nucleation and Growth at Liquid/Solid Interface

Unravelling dynamical processes of liquid droplets at liquid/solid interfaces and the interfacial ordering is critical to understanding solidification, liquid-phase epitaxial growth, wetting, liquid-phase joining, crystal growth, and lubrication process, all of which are linked to different important applications in material science. In this work, we observe direct in-situ atomic-scale behaviour of Bi droplets segregated on SrBi₂Ta₂O₉ by using aberration corrected transmission electron microscopy and demonstrate ordered interface and surface structures for the droplets on the oxide at the atomic-scale and unravel a nucleation mechanism involving droplet coalescence at the liquid/solid interface. We identify a critical diameter of the formed nanocrystal in stabilizing the crystalline phase and reveal lattice induced fast crystallization of the droplet at the initial stage of the coalescence of nanocrystal with droplet. Further sequential observations show the stepped coalescence and growth mechanism of the nanocrystals at the atomic-scale. These results offer insights into the dynamic process at liquid/solid interfaces, which may have implications for many functionalities of materials and their applications.

Direct Atomic-Scale Observation of Intermediate Pathways of Melting and Crystallization in Supported Bi-Nanoparticles

Uncovering the evolutional pathways of melting and crystallization atomically is critical to understanding complex microscopic mechanism of first-order phase transformation. Here, we conduct in-situ atomic-scale observations of melting and crystallization in supported Bi-nanoparticles under heating and cooling within an aberration-corrected TEM. We provide direct evidence to the multiple intermediate state events in melting and crystallization. The melting of the supported nanocrystal involves the formation and migration of domain boundaries and dislocations due to the atomic rearrangement under heating, which occurs through a size-dependent multiple intermediate state. A critical size, which is key to inducing the transition pathway in melting from two to four barriers, is identified for the nanocrystal. In contrast, crystallization of a Bi droplet involves three stages. These findings demonstrate that the phase transformations cannot be viewed as a simple single barrier- crossing event but as a complex multiple intermediate state phenomenon, highlighting the importance of nonlocal behaviors.

In situ Atomic-Scale Study of Particle Mediated Nucleation and Growth in Amorphous Bi to Nanocrystal Phase Transformation

Understanding classical and non-classical mechanisms of crystal nucleation and growth at the atomic scale has been of great interest to scientists in many disciplines. However, fulfilling direct atomic-scale observation still poses a significant challenge. Here, by taking a thin amorphous Bi metal nanosheet as a model system, we provide direct atomic resolution of the crystal nucleation and growth initiated from an amorphous state of Bi metal under electron beam inside an aberration corrected transmission electron microscope. We show that the crystal nucleation and growth in the phase transformation of Bi metal from amorphous to crystalline structure takes place via the particle-mediated non-classical mechanism instead of the classical atom-mediated mechanism. The dimension of the smaller particles in two contacted nanoparticles and their mutual orientation relationship are critical to governing several coalescence pathways: total rearrangement pathway, grain boundary migration dominated pathway and surface migration dominated pathway. Sequential strain analyses imply that migration of grain boundary is driven by strain difference in two Bi nanocrystals and the coalescence of nanocrystals is a defect reduction process. The findings may provide useful information on clarifying nanocrystal growth mechanisms of other materials at the atomic scale.

External Collaborations:

Prof. Yunping Li (State Key Lab for Powder Metallurgy, Central South University, Changsha 410083, China)

Dr. Qiang Li (School of Mechanical Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China).

C. Chen, Dr. H. Wang, and Prof. L. Guo (School of Chemistry and Environment, Beihang University Beijing 100191, China).

Prof. N. Chen (School of Materials Science and Engineering Tsinghua University Beijing 100084, China).

Dr. Zhongchang Wang (Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan).

Publications

• In-Situ Kinetic Observations on Crystal Nucleation and Growth, Junjie Li and Francis Leonard Deepak, Chem. Rev., 2022. .
• In-Situ Generation of Sub-10 nm Silver Nanowires under electron beam irradiation in the TEM, Junjie Li and Francis Leonard Deepak, Chem Comm, 2020, 56, 4765-4768 (Inside Front Cover Page).
• Atomic Scale dynamic observation reveals temperature-dependent multi-step nucleation pathways in crystallization, Junjie Li, Yunping Li, Qiang Li and Francis Leonard Deepak, Nanoscale Horiz, 2019, 4, 1302-1309 (Inside Back Cover).
• In-situ Atomic-Scale Observation of Kinetic Pathways of Sublimation in Silver Nanoparticles, Junjie Li, Zhongchang Wang, Yunping Li and Francis Leonard Deepak, Adv. Sci., 2019, 6, 1802131 (Frontispiece).
• In situ Atomic-Scale Study of Particle-Mediated Nucleation and Growth in Amorphous Bi to Nanocrystal Phase Transformation, Junjie Li, Jiangchun Chen, Hua Wang, Na Chen, Zhongchang Wang, Lin Guo and Francis Leonard Deepak, Adv. Sci., 2018, 1700992; DOI: 10.1002/advs.201700992.
• Direct Atomic-Scale Observation of Intermediate Pathways of Melting and   Crystallization in Supported Bi-Nanoparticles, Junjie Li, Zhongchang Wang and Francis Leonard Deepak, J. Phys. Chem. Lett., 2018, 9, 961-969.
• In Situ Atomic-Scale Observation of Droplet Coalescence Driven Nucleation and Growth at Liquid/Solid Interfaces, Junjie Li, Zhongchang Wang, and Francis Leonard Deepak, ACS Nano, 2017, 11 (6), pp 5590–5597.
• Real-Time Dynamical Observation of Lattice Induced Nucleation and Growth in Interfacial Solid-Solid Phase Transitions, Junjie Li, Qiang Li, Zhongchang Wang, and Francis Leonard Deepak, Cryst. Growth Des., 2016, 16, 7256−7262.

People in this Project: Loukya Boddapati, Rong Sun, E.A. Anumol and Francis Leonard Deepak

The hollow interior core of nanotubes, both carbon and non-carbon (BN, WS2 etc.) provide the necessary space for the filling, encapsulation and confinement of molecules and crystals both organic and inorganic. In addition they provide templates for the formation of core-shell nanotubes. The reduced dimensionality of the encapsulated material as a consequence of “confinement” presents the advantage of different characteristics compared to that of the bulk material. The interaction between the encapsulated material and the host nanotube plays a crucial role and therefore can govern the structure and electronic properties of such a system.
In this project nanotubes (CNTs as well as Inorganic NTs) which provide accessible space for templated growth of nanotubes or nanorods within them are employed to encapsulate metal halides such as GdI3 and BiI3 which are contrast agents for biomedical imaging. Capillary filling is employed to encapsulate these metal halides within nanotubes of carbon and WS2 to obtain core-shell nanotubes and/or nanorods. Aberration Corrected Scanning/Transmission Electron Microscopy and Spectroscopy using the Titan G2 80-200 TEM/STEM with ChemiSTEM Technology and FEI Titan Themis 60-300 kV is employed to characterize the atomic structure, morphology and composition of these core-shell structures.

External Collaborations
Dr. Pedro Costa and Mr. Nitin M. Batra (KAUST, Saudi Arabia)

Dr. Andrey Enyashin: Molecular Dynamics Simulation (Ural Federal University, Institute of Natural Sciences and Mathematics, Ekaterinburg, Russian Federation).

Go Kawamura and Wai Kian Tan: Toyohashi University of Technology

Publications

(1) Nanotube array-based barium titanate-cobalt ferrite composite film for affordable magnetoelectric multiferroics, Go Kawamura, Kentaro Oura, Wai Kian Tan, Taichi Goto, Yuichi Nakamura, Daisaku Yokoe, Francis Leonard Deepak, Khalil El Hajraoui, Xing Wei, Mitsuteru Inoue, Hiroyuki Muto, Kazuhiro Yamaguchi, Aldo R. Boccaccini and Atsunori Matsuda, J. Mater. Chem.C, 2019, 7, 10066-10072.

(2) N.M. Batra, E. A. Anumol, J. Smajic, A. N. Enyashin, F. L. Deepak and P. M. F. J. Costa, Morphological phase diagram of a metal halide encapsulated in carbon nanotubes,J. Phys. Chem C, 2018, 122, 24967-24976.

(3) E.A. Anumol, A. N. Enyashin, F. L. Deepak, Single Walled BiI₃ Nanotubes Encapsulated within Carbon Nanotubes, Scientific Reports 2018, 8, 10133.

(4) E. A. Anumol, F. L. Deepak, A. N. Enyashin, Capillary filling of carbon nanotubes by BiCl₃: TEM and MD insight, Nanosystems: Physics, Chemistry, Mathematics, 2018, 9 (4), P. 1-11.

(5) Capillary Imbibition of Gadolinium Halides into WS₂ Nanotubes: A Molecular Dynamics, Francis Leonard Deepak and A. N. Enyashin, Isr. J. Chem, Special Issue: Computational Science of Inorganic Nanostructures, 2017, 57, 501-508.

(6) Structural and chemical analysis of gadolinium halides encapsulated within WS2 nanotubes, E. A. Anumol, A. N. Enyashin, N. M. Batra, P. M. F. J. Costa and Francis Leonard Deepak, Nanoscale, 2016, 8, 12170-12181.

People in this Project: E.A. Anumol and Francis Leonard Deepak

In this project HAADF-STEM tomography is employed to obtain the 3D morphology of nanomaterials such as nanocatalysts and core-shell nanotubes. A Titan G2 80-200 TEM/STEM with ChemiSTEM Technology is used for this. EDX-STEM tomography is employed to obtain 3D chemical mapping. Low accelerating voltage (80 kV) enables tomography of beam sensitive materials such as carbon nanotubes. A high tilt tomography holder  and Super-X EDS detector (in the Titan ChemiSTEM) comprising four SDD detectors enable the EDX mapping in a wide tilt range (-70° to +70°) . Inspect 3D software is used for reconstruction and Amira for visualization.

External Collaborations

Dr. Pedro Costa and Mr. Nitin M. Batra (KAUST, Saudi Arabia)

Dr. Andrey Enyashin – Molecular Dynamics Simulation (Institute of Solid State Chemistry UB RAS Ekaterinburg, RUSSIAN FEDERATION).

Dr. C.P.Vinod – CSIR-National Chemical Laboratory, India

Publications

(1) Structural and chemical analysis of gadolinium halides encapsulated within WS₂ nanotubes, E. A. Anumol, A. N. Enyashin, N. M. Batra, P. M. F. J. Costa and Francis Leonard Deepak, Nanoscale, 2016, 8, 12170-12181.

(2) A Convenient Route for Au@Ti-SiO₂ Nanocatalyst Synthesis and its Application for Room Temperature CO Oxidation, A. Yogitha Soni, E. A. Anumol, Chandrani Nayak Francis Leonard Deepak, C. P. Vinod, Chathakudath, Phys. Chem. C 2017, 129, 4946-4957.

(3) A C Sunil Sekhar, Anumol E A, C T Cygnet, S Vidhya Lakshmi, Francis Leonard Deepak, C P Vinod, Mesoporous shell@macroporous core aluminosilicates as sustainable nanocatalysts for direct N-alkylation of Amines, ChemNanoMat, 2018, DOI: 10.1002/cnma.201800081 (VIP Article)

Highlight in Chemistry Views – May 01, 2018. (http://www.chemistryviews.org/details/ezine/11014918/Pores_for_Thought.html) DOI: 10.1002/chemv.201800036

ONGOING PROJECTS