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Full-Text Articles in Nanoscience and Nanotechnology

Minimalistic Peptide-Based Supramolecular Systems Relevant To The Chemical Origin Of Life, Daniela Kroiss Sep 2019

Minimalistic Peptide-Based Supramolecular Systems Relevant To The Chemical Origin Of Life, Daniela Kroiss

All Dissertations, Theses, and Capstone Projects

All forms of life are based on biopolymers, which are made up of a selection of simple building blocks, such as amino acids, nucleotides, fatty acids and sugars. Their individual properties govern their interactions, giving rise to complex supramolecular structures with highly specialized functionality, including ligand recognition, catalysis and compartmentalization. In this thesis, we aim to answer the question whether short peptides could have acted as precursors of modern proteins during prebiotic evolution. Using a combination of experimental and computational techniques, we screened a large molecular search space for peptide sequences that are capable of forming supramolecular complexes with adenosine ...


Synthesis And Optical Properties Of Ordered-Vacancy Perovskite Cesium Bismuth Halide Nanocrystals, Rainie D. Nelson, Kalyan Santra, Y. Wang, Atefe Hadi, Jacob W. Petrich, Matthew G. Panthani Aug 2019

Synthesis And Optical Properties Of Ordered-Vacancy Perovskite Cesium Bismuth Halide Nanocrystals, Rainie D. Nelson, Kalyan Santra, Y. Wang, Atefe Hadi, Jacob W. Petrich, Matthew G. Panthani

Matthew Panthani

Perovskite-phase cesium bismuth halide (Cs3Bi2X9; X = Cl, Br, I) nanocrystals were synthesized using a hot-injection approach. These nanocrystals adopted ordered-vacancy perovskite crystal structures and demonstrated composition-tunable optical properties. Growth occurred by initial formation of Bi0 seeds, and morphology was controlled by precursor and seed concentration. The Cs3Bi2I9 nanocrystals demonstrated excellent stability under ambient conditions for several months. Contrary to previous reports, we find that photoluminescence originates from the precursor material as opposed to the Cs3Bi2X9 nanocrystals.


Stamped Multilayer Graphene Laminates For Disposable In-Field Electrodes: Application To Electrochemical Sensing Of Hydrogen Peroxide And Glucose, Loreen R. Stromberg, John A. Hondred, Delaney Sanborn, Deyny Mendivelso-Perez, Srikanthan Ramesh, Iris V. Rivero, Josh Kogot, Emily Smith, Carmen Gomes, Jonathan C. Claussen Aug 2019

Stamped Multilayer Graphene Laminates For Disposable In-Field Electrodes: Application To Electrochemical Sensing Of Hydrogen Peroxide And Glucose, Loreen R. Stromberg, John A. Hondred, Delaney Sanborn, Deyny Mendivelso-Perez, Srikanthan Ramesh, Iris V. Rivero, Josh Kogot, Emily Smith, Carmen Gomes, Jonathan C. Claussen

Mechanical Engineering Publications

A multi-step approach is described for the fabrication of multi-layer graphene-based electrodes without the need for ink binders or post-print annealing. Graphite and nanoplatelet graphene were chemically exfoliated using a modified Hummers’ method and the dried material was thermally expanded. Expanded materials were used in a 3D printed mold and stamp to create laminate electrodes on various substrates. The laminates were examined for potential sensing applications using model systems of peroxide (H2O2) and enzymatic glucose detection. Within the context of these two assay systems, platinum nanoparticle electrodeposition and oxygen plasma treatment were examined as methods for improving sensitivity. Electrodes made ...


Stamped Multilayer Graphene Laminates For Disposable In-Field Electrodes: Application To Electrochemical Sensing Of Hydrogen Peroxide And Glucose, Loreen R. Stromberg, John A. Hondred, Delaney Sanborn, Deyny Mendivelso-Perez, Srikanthan Ramesh, Iris V. Rivero, Josh Kogot, Emily Smith, Carmen Gomes, Jonathan C. Claussen Jul 2019

Stamped Multilayer Graphene Laminates For Disposable In-Field Electrodes: Application To Electrochemical Sensing Of Hydrogen Peroxide And Glucose, Loreen R. Stromberg, John A. Hondred, Delaney Sanborn, Deyny Mendivelso-Perez, Srikanthan Ramesh, Iris V. Rivero, Josh Kogot, Emily Smith, Carmen Gomes, Jonathan C. Claussen

Carmen Gomes

A multi-step approach is described for the fabrication of multi-layer graphene-based electrodes without the need for ink binders or post-print annealing. Graphite and nanoplatelet graphene were chemically exfoliated using a modified Hummers’ method and the dried material was thermally expanded. Expanded materials were used in a 3D printed mold and stamp to create laminate electrodes on various substrates. The laminates were examined for potential sensing applications using model systems of peroxide (H2O2) and enzymatic glucose detection. Within the context of these two assay systems, platinum nanoparticle electrodeposition and oxygen plasma treatment were examined as methods for improving sensitivity. Electrodes made ...


Stamped Multilayer Graphene Laminates For Disposable In-Field Electrodes: Application To Electrochemical Sensing Of Hydrogen Peroxide And Glucose, Loreen R. Stromberg, John A. Hondred, Delaney Sanborn, Deyny Mendivelso-Perez, Srikanthan Ramesh, Iris V. Rivero, Josh Kogot, Emily Smith, Carmen Gomes, Jonathan C. Claussen Jul 2019

Stamped Multilayer Graphene Laminates For Disposable In-Field Electrodes: Application To Electrochemical Sensing Of Hydrogen Peroxide And Glucose, Loreen R. Stromberg, John A. Hondred, Delaney Sanborn, Deyny Mendivelso-Perez, Srikanthan Ramesh, Iris V. Rivero, Josh Kogot, Emily Smith, Carmen Gomes, Jonathan C. Claussen

Jonathan C. Claussen

A multi-step approach is described for the fabrication of multi-layer graphene-based electrodes without the need for ink binders or post-print annealing. Graphite and nanoplatelet graphene were chemically exfoliated using a modified Hummers’ method and the dried material was thermally expanded. Expanded materials were used in a 3D printed mold and stamp to create laminate electrodes on various substrates. The laminates were examined for potential sensing applications using model systems of peroxide (H2O2) and enzymatic glucose detection. Within the context of these two assay systems, platinum nanoparticle electrodeposition and oxygen plasma treatment were examined as methods for improving sensitivity. Electrodes made ...


Synthesis Of Germanium Nanocrystals From Solid-State Disproportionation Of A Chloride-Derived Germania Glass, Yujie Wang, Utkarsh Ramesh, Charles K. A. Nyamekye, Bradley J. Ryan, Rainie D. Nelson, Abdulla M. Alebri, Umar H. Hamdeh, Atefe Hadi, Emily A. Smith, Matthew G. Panthani Jun 2019

Synthesis Of Germanium Nanocrystals From Solid-State Disproportionation Of A Chloride-Derived Germania Glass, Yujie Wang, Utkarsh Ramesh, Charles K. A. Nyamekye, Bradley J. Ryan, Rainie D. Nelson, Abdulla M. Alebri, Umar H. Hamdeh, Atefe Hadi, Emily A. Smith, Matthew G. Panthani

Matthew Panthani

Germanium nanocrystals (Ge NCs) have potential to be used in several optoelectronic applications such as photodetectors and light-emitting diodes. Here, we report a solid-state route to synthesizing Ge NCs through thermal disproportionation of a germania (GeOX) glass, which was synthesized by hydrolyzing a GeCl2·dioxane complex. The GeOX glass synthesized in this manner was found to have residual Cl content. The process of nanocrystal nucleation and growth was monitored using powder X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. Compared to existing solid-state routes for synthesizing colloidal Ge NCs, this approach requires fewer steps and is amenable ...


Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans Jun 2019

Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans

James W. Evans

Self-assembly of supported 2D or 3D nanocrystals (NCs) by vacuum deposition and of 3D NCs by solution-phase synthesis (with possible subsequent transfer to a support) produces intrinsically nonequilibrium systems. Individual NCs can have far-from-equilibrium shapes and composition profiles. The free energy of NC ensembles is lowered by coarsening which can involve Ostwald ripening or Smoluchowski ripening (NC diffusion and coalescence). Preservation of individual NC structure and inhibition of coarsening are key, e.g., for avoiding catalyst degradation. This review focuses on postsynthesis evolution of metallic NCs. Atomistic-level modeling typically utilizes stochastic lattice-gas models to access appropriate time and length scales ...


Improving The Stability And Monodispersity Of Layered Cesium Lead Iodide Perovskite Thin Films By Tuning Crystallization Dynamics, Atefe Hadi, Bradley J. Ryan, Rainie D. Nelson, Kalyan Santra, Fang-Yi Lin, Eric W. Cochran, Matthew G. Panthani Jun 2019

Improving The Stability And Monodispersity Of Layered Cesium Lead Iodide Perovskite Thin Films By Tuning Crystallization Dynamics, Atefe Hadi, Bradley J. Ryan, Rainie D. Nelson, Kalyan Santra, Fang-Yi Lin, Eric W. Cochran, Matthew G. Panthani

Chemical and Biological Engineering Publications

Assembling halide perovskites into layered structures holds promise for addressing chemical and phase stability challenges; however, several other challenges need to be addressed to create efficient and stable halide perovskite devices. Layered halide perovskites (LHPs) suffer from broad distribution of layer thicknesses and bandgaps within thin films. Reducing polydispersity could substantially improve charge transport within LHP films and the performance of LHP-based solar cells. Herein, we focused on layering α-CsPbI3 ((C4H9NH3)2Csn-1PbnI3n+1) thin films. We found that (C4H9NH3)2Csn-1PbnI3n+1 with nominal layer thicknesses of n = 1, 2, 3, and 4 can be deposited at temperatures as low as ...


Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans Jun 2019

Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans

Chemistry Publications

Self-assembly of supported 2D or 3D nanocrystals (NCs) by vacuum deposition and of 3D NCs by solution-phase synthesis (with possible subsequent transfer to a support) produces intrinsically nonequilibrium systems. Individual NCs can have far-from-equilibrium shapes and composition profiles. The free energy of NC ensembles is lowered by coarsening which can involve Ostwald ripening or Smoluchowski ripening (NC diffusion and coalescence). Preservation of individual NC structure and inhibition of coarsening are key, e.g., for avoiding catalyst degradation. This review focuses on postsynthesis evolution of metallic NCs. Atomistic-level modeling typically utilizes stochastic lattice-gas models to access appropriate time and length scales ...


Synthesis Of Germanium Nanocrystals From Solid-State Disproportionation Of A Chloride-Derived Germania Glass, Yujie Wang, Utkarsh Ramesh, Charles K. A. Nyamekye, Bradley J. Ryan, Rainie D. Nelson, Abdulla M. Alebri, Umar H. Hamdeh, Atefe Hadi, Emily A. Smith, Matthew G. Panthani Apr 2019

Synthesis Of Germanium Nanocrystals From Solid-State Disproportionation Of A Chloride-Derived Germania Glass, Yujie Wang, Utkarsh Ramesh, Charles K. A. Nyamekye, Bradley J. Ryan, Rainie D. Nelson, Abdulla M. Alebri, Umar H. Hamdeh, Atefe Hadi, Emily A. Smith, Matthew G. Panthani

Chemical and Biological Engineering Publications

Germanium nanocrystals (Ge NCs) have potential to be used in several optoelectronic applications such as photodetectors and light-emitting diodes. Here, we report a solid-state route to synthesizing Ge NCs through thermal disproportionation of a germania (GeOX) glass, which was synthesized by hydrolyzing a GeCl2·dioxane complex. The GeOX glass synthesized in this manner was found to have residual Cl content. The process of nanocrystal nucleation and growth was monitored using powder X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. Compared to existing solid-state routes for synthesizing colloidal Ge NCs, this approach requires fewer steps and is amenable ...


Squeezed Nanocrystals: Equilibrium Configuration Of Metal Clusters Embedded Beneath The Surface Of A Layered Material, Scott E. Julien, Ann Lii-Rosales, Kai-Tak Wan, Yong Han, Michael C. Tringides, James W. Evans, Patricia A. Thiel Jan 2019

Squeezed Nanocrystals: Equilibrium Configuration Of Metal Clusters Embedded Beneath The Surface Of A Layered Material, Scott E. Julien, Ann Lii-Rosales, Kai-Tak Wan, Yong Han, Michael C. Tringides, James W. Evans, Patricia A. Thiel

Chemistry Publications

Shapes of functional metallic nanocrystals, typically synthesized either free in solution or supported on surfaces, are key for controlling properties. Here, we consider a novel new class of metallic nanocrystals, copper islands embedded near the surface of graphite, which can be considered a model system for metals embedded beneath surfaces of layered materials, or beneath supported membranes. We develop a continuum elasticity (CE) model for the equilibrium shape of these islands, and compare its predictions with experimental data. The CE model incorporates appropriate surface energy, adhesion energies, and strain energy. The agreement between the CE model and the data is ...


Kinetics, Energetics, And Size Dependence Of The Transformation From Pt To Ordered Ptsn Intermetallic Nanoparticles, Minda Chen, Yong Han, Tian Wei Goh, Rong Sun, Raghu V. Maligal‐Ganesh, Yuchen Pei, Chia‐ Kuang Tsung, James W. Evans, Wenyu Huang Jan 2019

Kinetics, Energetics, And Size Dependence Of The Transformation From Pt To Ordered Ptsn Intermetallic Nanoparticles, Minda Chen, Yong Han, Tian Wei Goh, Rong Sun, Raghu V. Maligal‐Ganesh, Yuchen Pei, Chia‐ Kuang Tsung, James W. Evans, Wenyu Huang

Chemistry Publications

The outstanding catalytic activity and chemical selectivity of intermetallic compounds make them excellent candidates for heterogeneous catalysis. However, the kinetics of their formation at the nanoscale is poorly understood or characterized, and precise control of their size, shape as well as composition during synthesis remains challenging. Here, using well-defined Pt nanoparticles (5 nm and 14 nm) encapsulated in mesoporous silica, we study the transformation kinetics from monometallic Pt to intermetallic PtSn at different temperatures by a series of time-evolution X-ray diffraction studies. Observations indicate an initial transformation stage mediated by Pt surface-controlled intermixing kinetics, followed by a second stage with ...


Potential Of Mean Force For Two Nanocrystals: Core Geometry And Size, Hydrocarbon Unsaturation, And Universality With Respect To The Force Field, Curt Waltmann, Nathan Horst, Alex Travesset Jul 2018

Potential Of Mean Force For Two Nanocrystals: Core Geometry And Size, Hydrocarbon Unsaturation, And Universality With Respect To The Force Field, Curt Waltmann, Nathan Horst, Alex Travesset

Ames Laboratory Accepted Manuscripts

We present a detailed analysis of the interaction between two nanocrystals capped with ligands consisting of hydrocarbon chains by united atom molecular dynamics simulations. We analyze large cores (up to 10 nm in diameter) and ligands with unsaturated carbon bonds (oleic acid) and we investigate the accuracy of the computed potential of mean force by comparing different force fields. We also analyze the vortices that determine the bonding, including the case of asymmetric nanocrystals, and discuss effects related to the intrinsic anisotropy of the core. Overall our results are in agreement with the predictions of the recently proposed orbifold topological ...


Creating Metamaterial Building Blocks With Directed Photochemical Metallization Of Silver Onto Dna Origami Templates, Md Mir Hossen, Lee Bendickson, Pierre Palo, Zhiqi Yao, Marit Nilsen-Hamilton, Andrew C. Hillier Jun 2018

Creating Metamaterial Building Blocks With Directed Photochemical Metallization Of Silver Onto Dna Origami Templates, Md Mir Hossen, Lee Bendickson, Pierre Palo, Zhiqi Yao, Marit Nilsen-Hamilton, Andrew C. Hillier

Ames Laboratory Accepted Manuscripts

DNA origami can be used to create a variety of complex and geometrically unique nanostructures that can be further modified to produce building blocks for applications such as in optical metamaterials. We describe a method for creating metal-coated nanostructures using DNA origami templates and a photochemical metallization technique. Triangular DNA origami forms were fabricated and coated with a thin metal layer by photochemical silver reduction while in solution or supported on a surface. The DNA origami template serves as a localized photosensitizer to facilitate reduction of silver ions directly from solution onto the DNA surface. The metallizing process is shown ...


Large-Scale Synthesis Of Colloidal Si Nanocrystals And Their Helium Plasma Processing Into Spin-On, Carbon-Free Nanocrystalline Si Films, Pratyasha Mohapatra, Deyny Mendivelso-Perez, Jonathan M. Bobbitt, Santosh Shaw, Bin Yuan, Xinchun Tian, Emily A. Smith, Ludovico Cademartiri May 2018

Large-Scale Synthesis Of Colloidal Si Nanocrystals And Their Helium Plasma Processing Into Spin-On, Carbon-Free Nanocrystalline Si Films, Pratyasha Mohapatra, Deyny Mendivelso-Perez, Jonathan M. Bobbitt, Santosh Shaw, Bin Yuan, Xinchun Tian, Emily A. Smith, Ludovico Cademartiri

Ames Laboratory Accepted Manuscripts

This paper describes a simple approach to the large-scale synthesis of colloidal Si nanocrystals and their processing into spin-on carbon-free nanocrystalline Si films. The synthesized silicon nanoparticles are capped with decene, dispersed in hexane, and deposited on silicon substrates. The deposited films are exposed to nonoxidizing room-temperature He plasma to remove the organic ligands without adversely affecting the silicon nanoparticles to form crack-free thin films. We further show that the reactive ion etching rate in these films is 1.87 times faster than that for single-crystalline Si, consistent with a simple geometric argument that accounts for the nanoscale roughness caused ...


The Crystal Facet-Dependent Electrochemical Performance Of Tio2 Nanocrystals For Heavy Metal Detection: Theoretical Prediction And Experimental Proof, Jianjun Liao, Fan Yang, Cai-Zhuang Wang, Shiwei Lin May 2018

The Crystal Facet-Dependent Electrochemical Performance Of Tio2 Nanocrystals For Heavy Metal Detection: Theoretical Prediction And Experimental Proof, Jianjun Liao, Fan Yang, Cai-Zhuang Wang, Shiwei Lin

Ames Laboratory Accepted Manuscripts

Tailored design/fabrication of electroanalytical materials with highly-active exposed crystal planes is of great importance for the development of electrochemical sensing. In this work, combining experimental and theoretical efforts, we reported a facile strategy to fabricate TiO2 nanocrystals with tunable electrochemical performance for heavy metal detection. Density functional theory (DFT) calculations indicated that TiO2 (001) facet showed relative larger adsorption energy and lower diffusion energy barrier toward heavy metal ions, which is favorable for obtaining better electrochemical stripping behaviors. Based on this prediction, a series of TiO2 nanocrystals with different ratios of exposed (001) and (101) facets were synthesized. Electrochemical ...


From Flasks To Applications: Design And Optimization Of Giant Quantum Dots Using Traditional And Automated Synthetic Methods, Christina J. Hanson Apr 2018

From Flasks To Applications: Design And Optimization Of Giant Quantum Dots Using Traditional And Automated Synthetic Methods, Christina J. Hanson

Nanoscience and Microsystems ETDs

Semiconducting nanocrystals, also known as quantum dots (QDs), that emit light with near-unity quantum yield and are extremely photostable are attractive options as down-conversion and direct electricity-to-light materials for a variety of applications including solid-state lighting, display technologies, bio-imaging and optical tracking. Standard QDs with a core/thin shell structure display fluorescence intermittency (blinking) and photobleaching when exposed to prolonged room temperature excitation for single dot measurements, as well as significant reabsorption and energy transfer when densely packed into polymers or at high solution concentrations.

We have developed thick shell “giant” QDs (gQDs), ultra-stable photon sources both at the ensemble ...


Functionalized Nanoporous Carbon Scaffolds For Hydrogen Storage Applications, Christopher Carr Mar 2018

Functionalized Nanoporous Carbon Scaffolds For Hydrogen Storage Applications, Christopher Carr

Dissertations

Recent efforts have demonstrated confinement in porous scaffolds at the nanoscale can alter the hydrogen sorption properties of metal hydrides, though not to an extent feasible for use in onboard hydrogen storage applications, proposing the need for a method allowing further modifications. The work presented here explores how the functionalization of nanoporous carbon scaffold surfaces with heteroatoms can modify the hydrogen sorption properties of confined metal hydrides in relation to non-functionalized scaffolds (FS). Investigations of nanoconfined LiBH4and NaAlH4indicate functionalizing the carbon scaffold surface with nitrogen can shift the activation energy of hydrogen desorption in excess of ...


Synthesis And Optical Properties Of Ordered-Vacancy Perovskite Cesium Bismuth Halide Nanocrystals, Rainie D. Nelson, Kalyan Santra, Y. Wang, Atefe Hadi, Jacob W. Petrich, Matthew G. Panthani Mar 2018

Synthesis And Optical Properties Of Ordered-Vacancy Perovskite Cesium Bismuth Halide Nanocrystals, Rainie D. Nelson, Kalyan Santra, Y. Wang, Atefe Hadi, Jacob W. Petrich, Matthew G. Panthani

Ames Laboratory Accepted Manuscripts

Perovskite-phase cesium bismuth halide (Cs3Bi2X9; X = Cl, Br, I) nanocrystals were synthesized using a hot-injection approach. These nanocrystals adopted ordered-vacancy perovskite crystal structures and demonstrated composition-tunable optical properties. Growth occurred by initial formation of Bi0 seeds, and morphology was controlled by precursor and seed concentration. The Cs3Bi2I9 nanocrystals demonstrated excellent stability under ambient conditions for several months. Contrary to previous reports, we find that photoluminescence originates from the precursor material as opposed to the Cs3Bi2X9 nanocrystals.


Nanoscale Mechanisms For High-Pressure Mechanochemistry: A Phase Field Study, Mahdi Javanbakht, Valery I. Levitas Mar 2018

Nanoscale Mechanisms For High-Pressure Mechanochemistry: A Phase Field Study, Mahdi Javanbakht, Valery I. Levitas

Aerospace Engineering Publications

Coupled evolution of a high-pressure phase (HPP) and dislocations, including dislocation pileups and dislocations generated due to phase transformation (PT), under compression and shear of a nanograined bicrystal, is considered as a model for high-pressure mechanochemistry. Recently developed phase field approach for the interaction between PTs and dislocations at large strains and a finite element analysis are utilized. Periodic boundary conditions for displacements are applied to the lateral surfaces. It is confirmed that the shear-induced dislocation pileups may reduce the PT pressure by an order of magnitude in comparison with hydrostatic loading, and even below phase equilibrium pressure, as it ...


Development Of A Semigraphitic Sulfur-Doped Ordered Mesoporous Carbon Material For Electroanalytical Applications, Jaqueline R. Maluta, Sergio A.S. Machado, Umesh Chaudhary, J. Sebastian Manzano, Lauro T. Kubota, Igor I. Slowing Mar 2018

Development Of A Semigraphitic Sulfur-Doped Ordered Mesoporous Carbon Material For Electroanalytical Applications, Jaqueline R. Maluta, Sergio A.S. Machado, Umesh Chaudhary, J. Sebastian Manzano, Lauro T. Kubota, Igor I. Slowing

Ames Laboratory Accepted Manuscripts

The modification of traditional electrodes with mesoporous carbons is a promising strategy to produce high performance electrodes for electrochemical sensing. The high surface area of mesoporous carbons provides a large number of electroactive sites for binding analytes. Controlling the pore size and structure of mesoporous carbons and modifying their electronic properties via doping offers additional benefits like maximizing transport and tuning the electrochemical processes associated with analyte detection. This work reports a facile method to produce sulfur-doped ordered mesoporous carbon materials (S-OMC) with uniform pore structure, large pore volume, high surface area and semigraphitic structure. The synthesis used thiophenol as ...


Mechanochemistry Of The Libh4–Alcl3 System: Structural Characterization Of The Products By Solid-State Nmr, Takeshi Kobayashi, Oleksandr Dolotko, Shalbh Gupta, Vitalij K. Pecharsky, Marek Pruski Feb 2018

Mechanochemistry Of The Libh4–Alcl3 System: Structural Characterization Of The Products By Solid-State Nmr, Takeshi Kobayashi, Oleksandr Dolotko, Shalbh Gupta, Vitalij K. Pecharsky, Marek Pruski

Ames Laboratory Accepted Manuscripts

The double-cation metal borohydride, Li4Al3(BH4)(13), mechanochemically produced from a 13:3 mixture of lithium borohydride (LiBH4) and aluminum chloride (AlCl3), has a low hydrogen desorption temperature; however, the material's decomposition is accompanied by a large emission of toxic diborane (B2H6). We found that a decrease of the LiBH4:AICl(3) ratio in the starting mixture yields increased amounts of partially chlorinated products that also dehydrogenate at low temperature, but release negligibly small amounts of diborane. Extensive characterization by solid-state NMR spectroscopy (SSNMR) and powder X-ray diffraction (XRD) found that the 11:3 ratio product maintains the Li ...


Hybrid Electrochemical Capacitors: Materials, Optimization, And Miniaturization, Richa Agrawal Jan 2018

Hybrid Electrochemical Capacitors: Materials, Optimization, And Miniaturization, Richa Agrawal

FIU Electronic Theses and Dissertations

With the ever-advancing technology, there is an incessant need for reliable electrochemical energy storage (EES) components that can provide desired energy and power. At the forefront of EES systems are electrochemical capacitors (ECs), also known as supercapacitors that typically have higher power and superior cycle longevity but lower energy densities than their battery counterparts. One of the routes to achieve higher energy density for ECs is using the hybrid EC configuration, which typically utilizes a redox electrode coupled with a counter double-layer type electrode.

In this dissertation, both scale-up (coin-cell type) as well as scale-down (on-chip miniaturized) hybrid ECs were ...


Designing Materials For Inorganic And Living Photocatalytic Systems For Air, Water, And Co2 Reduction From Sunlight, Yuchen Ding Jan 2018

Designing Materials For Inorganic And Living Photocatalytic Systems For Air, Water, And Co2 Reduction From Sunlight, Yuchen Ding

Chemistry & Biochemistry Graduate Theses & Dissertations (1986-2018)

Several strategies are currently being investigated for conversion of incident sunlight into chemical fuels, with readily available chemical feedstocks like air, water, and carbon-dioxide. This thesis focuses on research approach on designing high-efficiency and high-selective photocatalytic materials, ranging from inexpensive and stable inorganic photocatalysts to living nano-biohybrid organisms to achieve solar energy conversion.

This thesis is divided into multiple sections based on the materials and concepts in designing high-efficient and high-selective solar fuel generator. After a brief introduction of photocatalysis in Chapter 1, we describe a novel electrochemical anodization technique for making a wide-variety of doped metal-oxide nanotubes. Using optoelectronic ...


Ordered Networks Of Gold Nanoparticles Crosslinked By Dithiol‐Oligomers, Srikanth Nayak, Nathan Horst, Honghu Zhang, Wenjie Wang, Surya Mallapragada, Alex Travesset, David Vaknin Jan 2018

Ordered Networks Of Gold Nanoparticles Crosslinked By Dithiol‐Oligomers, Srikanth Nayak, Nathan Horst, Honghu Zhang, Wenjie Wang, Surya Mallapragada, Alex Travesset, David Vaknin

Chemical and Biological Engineering Publications

Controlled aggregation of nanoparticles into superlattices is a grand challenge in material science, where ligand based self‐assembly is the dominant route. Here, the self‐assembly of gold nanoparticles (AuNPs) that are crosslinked by water soluble oligo‐(ethylene glycol)‐dithiol (oEG‐dithiol) is reported and their 3D structure by small angle X‐ray scattering is determined. Surprisingly, a narrow region is found in the parameter space of dithiol linker‐length and nanoparticle size for which the crosslinked networks form short‐ranged FCC crystals. Using geometrical considerations and numerical simulations, the stability of the formed lattices is evaluated as a function ...


Three-Dimensional Nanomaterials For Supercapacitor Applications: From Metal Oxides To Metal Phosphides, Zhi Zheng Dec 2017

Three-Dimensional Nanomaterials For Supercapacitor Applications: From Metal Oxides To Metal Phosphides, Zhi Zheng

University of New Orleans Theses and Dissertations

Over the past few years, energy storage devices have received tremendous interest due to the increasing demand for sustainable and renewable energy in modern society. Supercapacitors are considered as one of the most promising energy storage devices because of their high power density and long cycle life. However, low energy density remains as the main shortcoming for supercapacitors. The overall performance of supercapacitors is predominantly determined by the characteristics of the electrodes. Specifically, constructing nanostructured electrode material has been proven as an efficient way to improve the performance by providing large surface area and short ionic and electronic diffusion paths ...


Vertically-Aligned Mn(Oh)2 Nanosheet Films For Flexible All-Solid-State Electrochemical Supercapacitors, Ziyuan Yang, Jiangfeng Gong, Chunmei Tang, Weihua Zhu, Zhaojun Cheng, Jinghua Jiang, Aibin Ma, Qingping Ding Dec 2017

Vertically-Aligned Mn(Oh)2 Nanosheet Films For Flexible All-Solid-State Electrochemical Supercapacitors, Ziyuan Yang, Jiangfeng Gong, Chunmei Tang, Weihua Zhu, Zhaojun Cheng, Jinghua Jiang, Aibin Ma, Qingping Ding

Ames Laboratory Accepted Manuscripts

The arrangement of the electrode materials is a significant contributor for constructing high performance supercapacitor. Here, vertically-aligned Mn(OH)2 nanosheet thin films were synthesized by cathodic electrodeposition technique on flexible Au coated polyethylene terephthalate substrates. Morphologies, microstructures, chemical compositions and valence state of the nanosheet films were characterized systematically. It shows that the nanosheets arranged vertically to the substrate, forming a porous nanowall structures and creating large open framework, which greatly facilitate the adsorption or diffusion of electrolyte ions for faradaic redox reaction. Electrochemical tests of the films show the specific capacitance as high as 240.2 F g ...


Investigating Scalable Manufacturing Of High-Conductivity Wires And Coatings From Ultra-Long Carbon Nanotubes, Pouria Khanbolouki Nov 2017

Investigating Scalable Manufacturing Of High-Conductivity Wires And Coatings From Ultra-Long Carbon Nanotubes, Pouria Khanbolouki

Mechanical Engineering ETDs

Carbon nanotubes (CNTs) are a promising candidate for next generation of electrical wirings and electromagnetic interference (EMI) shielding materials due to their exceptional mechanical and electrical properties. Wires and coatings from ultralong nanotubes that are highly crystalline, well-aligned and densely packed can achieve this goal. High-performance CNT conductors will be relatively lightweight and resistant to harsh conditions and therefore can potentially replace current conductors in many industries including aerospace, automotive, gas and oil.

This thesis investigates a new manufacturing approach, based on conventional solution coating and wire drawing methods, to fabricate high conductivity wires and coatings from ultra-long carbon nanotubes ...


Interfacial Charge Distributions In Carbon-Supported Palladium Catalysts, Radhika Rao, Raoul Blume, Thomas W. Hansen, Erika Fuentes, Kathleen Dreyer, Simona Moldovan, Ovidiu Ersen, David D. Hibbitts, Yves J. Chabal, Robert Schlögl, Jean-Philippe Tessonnier Aug 2017

Interfacial Charge Distributions In Carbon-Supported Palladium Catalysts, Radhika Rao, Raoul Blume, Thomas W. Hansen, Erika Fuentes, Kathleen Dreyer, Simona Moldovan, Ovidiu Ersen, David D. Hibbitts, Yves J. Chabal, Robert Schlögl, Jean-Philippe Tessonnier

Chemical and Biological Engineering Publications

Controlling the charge transfer between a semiconducting catalyst carrier and the supported transition metal active phase represents an elite strategy for fine turning the electronic structure of the catalytic centers, hence their activity and selectivity. These phenomena have been theoretically and experimentally elucidated for oxide supports but remain poorly understood for carbons due to their complex nanoscale structure. Here, we combine advanced spectroscopy and microscopy on model Pd/C samples to decouple the electronic and surface chemistry effects on catalytic performance. Our investigations reveal trends between the charge distribution at the palladium–carbon interface and the metal’s selectivity for ...


Mechanistic Insight Into Nanoparticle Surface Adsorption By Solution Nmr Spectroscopy In An Aqueous Gel, Timothy K. Egner, Pranjali Naik, Nicholas C. Nelson, Igor I. Slowing, Vincenzo Venditti Aug 2017

Mechanistic Insight Into Nanoparticle Surface Adsorption By Solution Nmr Spectroscopy In An Aqueous Gel, Timothy K. Egner, Pranjali Naik, Nicholas C. Nelson, Igor I. Slowing, Vincenzo Venditti

Chemistry Publications

Engineering nanoparticle (NP) functions at the molecular level requires a detailed understanding of the dynamic processes occurring at the NP surface. Herein we show that a combination of dark‐state exchange saturation transfer (DEST) and relaxation dispersion (RD) NMR experiments on gel‐stabilized NP samples enables the accurate determination of the kinetics and thermodynamics of adsorption. We used the former approach to describe the interaction of cholic acid (CA) and phenol (PhOH) with ceria NPs with a diameter of approximately 200 nm. Whereas CA formed weak interactions with the NPs, PhOH was tightly bound to the NP surface. Interestingly, we ...