Functional Nanomaterials: Functional Low-Dimensional (0D, 1D, 2D) Materials 2022: Low-Dimensional Materials Synthesis
Sponsored by: TMS Functional Materials Division, TMS: Nanomaterials Committee
Program Organizers: Michael Cai Wang, University of South Florida; Yong Lin Kong, University of Utah; Sarah Ying Zhong, University of South Florida; Surojit Gupta, University of North Dakota; Nasrin Hooshmand, Georgia Institute of Technology; Woochul Lee, University of Hawaii at Manoa; Min-Kyu Song, Washington State University; Simona Hunyadi Murph, Savannah River National Laboratory; Hagar Labouta, University of Manitoba; Max Anikovskiy, University of Calgary; Patrick Ward, Savannah River National Laboratory

Monday 2:00 PM
February 28, 2022
Room: 260B
Location: Anaheim Convention Center

Session Chair: Woochull Lee, University of Hawaiʻi at Mānoa; Michael Cai Wang, University of South Florida

2:00 PM  
Water-driven CH3NH3PbBr3 Nanocrystals: Fuqian Yang1; 1University of Kentucky
     There is great interest to prepare perovskite nanocrystals environmental-friendly. In this work, we develop a green route to synthesize CH3NH3PbBr3 nanocrystals with deionized water as precursor solvent. The prepared CH3NH3PbBr3 nanocrystals exhibit a PL peak at 511 nm and a photoluminescence quantum yield (PLQY) of 89.9%. Using the CH3NH3PbBr3 nanocrystals, we prepare poly(methyl methacrylate)-MAPbBr3 NC films. The PMMA-NC films can retain ~89.2% of its initial PL intensity after 720 h aging at 50 C and 70 C, respectively. The method developed in this work provides a simple technique to prepare CH3NH3PbBr3 nanocrystals environmental-friendly.FY is grateful for the support by the NSF through the grant CMMI-1854554, monitored by Drs. Khershed Cooper and Thomas Francis Kuech, and CBET- 2018411 monitored by Dr. Nora F Savage.

2:20 PM  
Tuning the Rapid Thermochemical Pretreatment of Alumina-supported Iron Catalyst to Improve Catalytic Lifetime in Chemical Vapor Deposition of Carbon Nanotubes: Golnaz Tomaraei1; Jaegeun Lee1; Moataz Abdulhafez1; Mostafa Bedewy1; 1University of Pittsburgh
    One problem in chemical vapor deposition (CVD) of carbon nanotubes (CNTs) using oxide-supported metal catalysts is the limited catalytic lifetime. The initial state of catalyst nanoparticles is determined during the formation stage via solid-state thin film dewetting in a reducing environment. Catalyst nanoparticles continue to evolve during CNT growth until deactivation by chemical poisoning, carbon overcoating, or catalyst loss by migration to the surface or underlying layer. These deactivation mechanisms rely on both catalyst formation and CNT growth conditions. Therefore, boosting catalytic lifetime requires optimizing these steps independently. We use a custom-designed multizone, rapid thermal processing CVD reactor to tune the rapid thermochemical pretreatment of alumina-supported iron catalyst, independently from the catalyst activation and CNT growth steps. We show that increasing the catalyst nanoparticle formation temperature to 900 C in hydrogen results in denser and less porous alumina thin films, postponing deactivation by suppressing catalyst diffusion into the support layer.

2:40 PM  
NOW ON-DEMAND ONLY – Salt Treatment to Purify Carbon Nanotube Sheets Produced via the Floating Catalyst CVD Method: Anuptha Pujari1; Arun Bhattacharjee2; Ashley Paz y Puente1; Mark Schulz1; 1University of Cincinnati; 2Pacific Northwest National Laboratory
    The floating catalyst CVD method is a synthesis technique to produce macroscopic CNT sheets. This method uses a catalyst that is mixed with alcohol fuel along with other carbon precursors, thereby eliminating the use of a substrate to grow the CNTs. Although this method produces high yields of macroscopic CNT sheets, large amounts of undesired residual metallic catalyst particles are entrapped within the CNT sheets. Here, we have performed a novel salt treatment of the CNT sheets to remove the residual catalyst particles using NH4Cl. A kinetic study of the removal of metallic particles was performed for 10, 20, and 30 mins. Characterization of the salt-treated and as-synthesized CNT sheets was performed using electron microscopy, raman spectroscopy and 4-point probe. The characterization results revealed a strong correlation between the amount of residual materials (metallic particles and amorphous carbon) removed and processing time.

3:00 PM  
Thermal Conductivity Enhancement of PEO/PEDOT:PSS Composite Nanofiber: Anh Tuan Nguyen1; Woochul Lee1; 1University of Hawaii at Manoa
    Polymers are used in various applications due to their excellent properties of lightweight, low cost, flexibility, and chemical stability. However, use of polymers is limited in thermal applications due to their low thermal conductivity. To overcome this limitation, many studies have been conducted to improve the thermal conductivity of polymers. Electrospinning process is a popular and inexpensive method to fabricate nanofibers. This fabrication process can alter polymers’ internal structures such as crystallinity and molecular chain alignment, which can greatly affect thermal conductivity. Numerous nanofibers such as polyethylene, polyethylene oxide (PEO), polyethylene, polystyrene, and nylon were produced by electrospinning. These nanofibers exhibit significantly enhanced thermal conductivity compared to their bulk counterpart. In this study, we measure thermal conductivity of electrospun PEO/PEDOT:PSS nanofibers produced by varying electrospinning process parameters. We will discuss thermal conductivity variation on electrospinning process parameters and the relation between nanofiber’s internal structure and thermal conductivity.

3:20 PM Break

3:40 PM  
The Scaling of Low-temperature Ferroelectric Hf0.5Zr0.5O2 Thin Films Using Anhydrous H2O2: Yong Chan Jung1; Jin-Hyun Kim1; Jaidah Mohan1; Heber Hernandez-Arriaga1; Su Min Hwang1; Daniel Alvarez2; Jeffrey Spiegelman2; Si Joon Kim3; Jiyoung Kim1; 1The University of Texas at Dallas; 2RASIRC; 3Kangwon National University
     In this study, the effect of film thickness and anhydrous H2O2 on ferroelectric properties of low-temperature Hf0.5Zr0.5O2 (HZO) films are investigated. In our previous study, it was reported that very thin (~5 nm) films required higher energy for crystal nucleation and growth [1]. Interestingly, an oxygen source of the anhydrous H2O2 acts as a good chemically driven densifier by producing highly dense hydroxyl surface [2]. As a result, the 10 and 7 nm-thick HZO were crystallized at the deposition temperature of 300 °C without annealing process. The 5 nm-thick HZO was crystallized into the ferroelectric orthorhombic phase during 400 °C annealing process. It is confirmed that anhydrous H2O2 reduces the crystallization temperature by enabling more closely compacted HZO film deposition. [1] S. J. Kim et al., Appl. Phys. Lett. 112, 172902 (2018).[2] S. W. Park et al., Surf. Sci. 652, 322 (2016)

4:00 PM  
Solid-State Transformation of 0D Metal Nanoparticles to Anisotropic 2D Morphologies: Md Rubayat-E Tanjil1; Tanuj Gupta2; Matthew Gole3; Zhewen Yin1; Keegan Suero1; Donald McCleeary1; Ossie Douglas1; Alissa Anderson1; Catherine Murphy3; Huijuan Zhao2; Michael Cai Wang1; 1University of South Florida; 2Clemson University; 3University of Illinois Urbana-Champaign
    Low-dimensional 0D metallic nanoparticles are intrinsically faceted with geometric shapes, exhibiting high structural symmetry due to net surface energy minimization during synthesis. Solution-based, seed-mediated colloidal synthesis have been the prevailing strategies for synthesizing asymmetry nanoparticles and achieving control of nanoparticle morphological anisotropy. In contrast, morphological control via top-down strategies has remained under-explored. In this report, a novel, solid-state, uniaxial compression fabrication technique is demonstrated, enabling deterministic control over nanoparticle morphological anisotropy. This generalizable technique facilitates the transformation of 0D (Au) nanoparticles into anisotropic two-dimensional (2D) morphologies. The post-compression morphology of 2D Au exhibits dependence on the individual precursor 0D nanoparticle morphology, dimensions (0D nanosphere diameter), and on-substrate arrangement (e.g., interparticle separation, packing order). Overall, this versatile and generalizable solid-state transformation technique enables new pathways to investigate the mechanics of anisotropic morphological transformation of arbitrary metallic nanoparticles and their emergent phenomena.

4:20 PM  Keynote
Wafer-scale Epitaxial Growth of 2D Transition Metal Dichalcogenides: Joan Redwing1; 1Pennsylvania State University
    Two-dimensional (2D) transition metal dichalcogenides (TMDs) comprise a compelling class of materials with intriguing properties that arise from their ultra-thin form, thickness-dependent band structure, large exciton binding energies and spin-valley polarization physics. Our research is aimed at the development of an epitaxial growth technology for semiconducting TMDs (MoS2, WSe2, etc.) based on metalorganic chemical vapor deposition (MOCVD) and focuses on understanding fundamentals of nucleation, epitaxy and anisotropic growth that are characteristic of van der Waals crystals. Point defects and surface steps are used to control the nucleation density and orientation of TMD domains as demonstrated for epitaxial growth on hBN and sapphire substrates, respectively. TMD monolayers grown by MOCVD on 2” sapphire exhibit optical and transport properties approaching that of single crystal flakes exfoliated from bulk crystals. Prospects and challenges associated with the epitaxial growth of vertical and lateral TMD heterostructures will also be discussed.