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Controlled Synthesis, Processing, and Applications of Structural and Functional Nanomaterials: On-Demand Oral Presentations
Sponsored by: ACerS Basic Science Division, ACerS Electronics Division, ACerS Engineering Ceramics Division
Program Organizers: Haitao Zhang, University of North Carolina at Charlotte; Gurpreet Singh, Kansas State University; Kathy Lu, University of Alabama Birmingham; Edward Gorzkowski, Naval Research Laboratory; Jian Shi, Rensselear Polytechnich University; Michael Naguib, Tulane University; Sanjay Mathur, University of Cologne

Friday 8:00 AM
October 22, 2021
Room: On-Demand Room 11
Location: MS&T On Demand

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Invited
Surface-engineered CeO2 Nanocrystals: Catalysis and Beyond: Ruigang Wang¹; ¹The University of Alabama
    Catalyst-support interaction and interface play a critical role in heterogeneous catalysis. CeO2 along with other oxides constitutes an important class of catalyst supports that can exchange oxygen rapidly under variable reducing or oxidizing conditions, which is mainly accomplished by a reversible valence change of the cerium ions (2Ce(IV)O2 <--> Ce2(III)O3 + 1/2O2) with formation or elimination of oxygen vacancies. Oxygen exchange or charge transfer during the reduction and oxidation (redox) processes are essential steps for many catalytic reactions at elevated temperatures. In this talk, I will present some recent progress on (1) synthesis and characterization of shape/crystal structure-controlled CeO2 support materials, (2) chemical etching surface modification of CeO2, (3) electrospinning synthesis of thermally stable CeO2 nanofibers, and (4) understanding the catalyst-support interaction and support promoting effect for many industrial catalysis applications such as in vehicle exhaust clean-up, carbon dioxide capture, and host materials of Li-S battery.

Invited
2D Material and van der Waal Heterostructure Nanoelectromechanical Systems (NEMS): Philip Feng¹; ¹University of Florida
    Emerging 2D semiconductors (such as transition metal dichalcogenides (TMDCs) and black phosphorus), along with their heterostructures (particularly with graphene and hexagonal boron nitride (h-BN) layers), offer compelling platforms for creating new nanoelectromechanical systems (NEMS) for multiphysical transducers, where the unconventional properties of these crystals are harnessed for engineering both classical and quantum signal processing and sensing schemes. In this presentation, I will describe some of my group’s latest endeavors on advancing resonant NEMS with 2D materials and van der Waals heterostructures. After reviewing important fundamentals of 2D NEMS, I will demonstrate examples of how the special properties of these 2D structures have led to new device functions and performance beyond conventional NEMS. Toward quantum engineering, atomistic defects in ultrawide-bandgap h-BN crystal support intriguing quantum emitters (QEs). Leveraging our experience in SiC and 2D devices, we explore these platforms and their hybrid integration, toward developing quantum transduction functions in chip-scale systems.

Invited
Effects of Layer Thickness and Constituent Material on the Wear and Corrosion Resistance of Nanostructured Multilayers: Wenbo Wang¹; Wenjun Cai¹; ¹Virginia Polytechnic Institute and State University
    Nanostructured multilayers are emerging materials with excellent mechanical, tribological, and corrosion properties, enabled by the presence of ultrafine layers and a high density of interfaces. In the present work, the wear, corrosion and tribocorrosion resistance of nanostructured multilayers of Al/X (X= Mg, Cu, and Ti) were studied via experiments, finite element simulations, and density functional theory calculations. Outstanding wear and corrosion resistance of the multilayers were observed, where the overall degradation was governed by the synergistic effects of the mechanical and corrosion properties of the constituting materials. Both layer thickness and orientation of the multilayers were found to affect the subsurface residual stress distribution and localized surface corrosion kinetics via finite element modeling. Finally, density functional calculations of their surfaces provide further insight on the material selection and design criteria for multilayers toward enhanced performance under extreme environment.

Invited
Nanocrystalline Refractory Ceramic Synthesis Using High Char Polymers: Matthew Laskoski¹; Boris Dyatkin¹; Tristan Butler¹; ¹US Naval Research Lab
    Ultra-high temperature ceramics (UHTCs) demonstrate significant promise in many high performance applications. However, existing processing typically produce macrocrystalline ceramics that are too brittle and expensive to incorporate into aerospace and military systems. Our approach produces dense, nanocrystalline, monolithic UHTC composites with precursor flexibility that can maximize density while altering hardness, and durability under high temperatures. This process is based on a novel synthesis route using compressed powder mixtures of metal precursors and high char-yielding that yield shaped carbides, nitrides, and borides under mild heat treatment. Incorporation of various metals, fibers, and ceramics into these composites can improve their mechanical, electrical, and thermal properties and adapt them for many emerging applications.

Invited
Supercrystalline Nanocomposites: Boosting and Controlling the Mechanical Behavior of These New Multifunctional Materials: Diletta Giuntini¹; Buesra Bor²; Alexander Plunkett²; Berta Domenech²; Gerold Schneider²; ¹Eindhoven University of Technology; ²Hamburg University of Technology
    Supercrystalline nanocomposites have emerged within the broader fields of hybrid and nanoarchitected materials. They consist of inorganic nanoparticles, functionalized with organic ligands and arranged into periodic structures, reminiscent of atomic crystals. The combination of nano-building blocks and their periodic arrangement leads to emergent functional properties, with applications in optoelectronics, magnetic devices, catalysis, and more. A remarkable example is the fabrication of bulk superparamagnetic materials. A major obstacle towards their exploitation into devices is the lack of information on their mechanical behavior, accompanied by poor mechanical properties. An important step forward has been made by crosslinking the organic phase that interfaces the nanoparticles. This covalent network alters the deformation behavior of the nanocomposites, as multiscale ex- and in-situ studies show. Many analogies with atomic crystals emerge, even if length-scale and interactions between building blocks vary significantly. Future directions towards supercrystals with tunable behavior are outlined.

Invited
Controlling Synthesis of Nanostructures with Nanoscale Phase Diagrams: Ricardo Castro¹; ¹University of California, Davis
    Nanomaterials are considered metastable structures due to the excess energy coming from the interfacial regions. These energies include surfaces and grain boundaries, and can significantly increase the overall energy of the system due to the unsatisfied bonds and ionic coordination. A fair description of nanoscale thermodynamics must thus include interfacial energies in addition to bulk energies used in conventional phase diagrams. Not surprisingly, similarly to bulk thermodynamics, interfacial energies also vary with composition and crystallographic structures. As a result, the thermodynamics of nano-oxides is not simple to assess, and determining the ‘meta’ stable phase requires a combination of interfacial energies and microstructure (particularly surface and grain boundary areas). Here we present a series of microcalorimetric data which reveal polymorphic energetic trends in nano-oxides. Zirconium based oxides are initially used as the foundation for the analyses, but we further introduce new data for other functional oxides, including TiO2 and LiMn2O4.


Ti3C2 MXene-polyvinyl Alcohol Hybrids for Photothermal Self-healing: Yi Je Cho¹; Kathy Lu²; ¹Virginia Tech; ²Virginia Polytechnic Institute and State University
    Functional nano-sized additives in polymers are an exciting class of hybrid materials that can tailor desirable characteristics of multiple species and realize new functionality. MXene Ti3C2 has become a candidate for self-healing hybrids. It possesses unique metallic conductivity, high aspect ratio, and broad absorption band. The self-healing properties converting electromagnetic radiation to heat depend on the absorption efficiency of Ti3C2 that varies with its concentration, geometry, size, spatial distribution, and orientation. Therefore, understanding the microstructure effect on both the optical and photothermal behaviors is important to develop a new self-healing hybrid. In addition, numerical modeling can shed light on the theoretical photothermal behaviors, which can account for many aspects of the phenomenon that cannot be experimentally obtained. In this study, the self-healing properties of two different structured Ti3C2-polyvinyl alcohol hybrid films are investigated. The characteristics of Ti3C2 and photo-induced healing behaviors are examined experimentally and numerically.


Universal Approach towards Metal Chalcogenide Materials from Molecular Building Blocks: Veronika Brune¹; Sanjay Mathur¹; ¹University of Cologne
     The lacking control of large scale and homogeneous formation of vdW 2D materials MS₂, MS and alkali metal sulfide materials M₂S in commercial formation processes motivated us to develop a unique synthetic approach to layered 2D materials. A uniform synthesis route of molecular building blocks for controlled formation of stable precursor classes [M(SEtN(Me)EtS)_x] (M = Mo^IV, W^IV, Ti^IV, x = 2; M = Ge^II, Sn^II, x = 1) and [(MSEt)₂NMe] (M = Li, Na) was established. Following simple synthetic protocols, the reaction of SNS donor ligand with suitable metal compounds resulted in (air)stable molecular precursors, which enable the targeted formation of homogeneous crystalline 2D MoS₂, WS₂, TiS₂, SnS₂, SnS and alkali metal based Li₂S and Na₂S by thermal decomposition experiments as well as in wet chemical syntheses via microwave assisted decomposition resulting in SnS₂ particles. These molecular building blocks provide an extraordinary synthetic approach to a unique molecular precursor class.


Single Acid One-pot Process as an Effective Method for Controlled Generation of Coal-derived Graphene Quantum Dots (GQDs): Saurav Kar¹; Roop Mahajan¹; ¹Virginia Polytechnic Institute and State University
    In this paper, we present the potential of our in-house developed one-pot process to convert coal to multilayer graphene for generating quantum dots. Coal with its graphene domains and amorphous carbon chunks is a promising source of GQDs, however, the effect of its structure on GQD properties is not fully understood. To this end, GQDs were exfoliated from various grades of coal using our one-pot process and characterized. The effect of acid concentration and temperature on GQD properties were also studied. The results indicate that the GQD size and yield are highly dependent on inherent carbon domain sizes. Temperature and acid concentrations are also effective in modifying GQD size, but with less pronounced effects. The comparatively simpler one-pot process was found to be highly effective in GQD exfoliation. It has also been shown that carbon domain size can be used as a simple and effective determinant of GQD size.

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