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Articles 1 - 30 of 1489

Full-Text Articles in Materials Chemistry

Non-Equilibrium Growth Of Metal Clusters On A Layered Material: Cu On Mos2, Dapeng Jing, Ann Lii-Rosales, King C. Lai, Qiang Li, Jaeyoun Kim, Michael C. Tringides, James W. Evans, Patricia A. Thiel May 2020

Non-Equilibrium Growth Of Metal Clusters On A Layered Material: Cu On Mos2, Dapeng Jing, Ann Lii-Rosales, King C. Lai, Qiang Li, Jaeyoun Kim, Michael C. Tringides, James W. Evans, Patricia A. Thiel

Chemistry Publications

We use a variety of experimental techniques to characterize Cu clusters on bulk MoS2 formed via physical vapor deposition of Cu in ultrahigh vacuum, at temperatures ranging from 300 K to 900 K. We find that large facetted clusters grow at elevated temperatures, using high Cu exposures. The cluster size distribution is bimodal, and under some conditions, large clusters are surrounded by a denuded zone. We propose that defect-mediated nucleation, and coarsening during deposition, are both operative in this system. At 780 K, a surprising type of facetted cluster emerges, and at 900 K this type predominates: pyramidal clusters with ...


Ternary Polar Intermetallics Within The Pt/Sn/R Systems (R = La− Sm): Stannides Or Platinides?, Melissa L. Rhodehouse, Volodymyr Smetana, Chris Celania, Anja-Verena Mudring, Gerd H. Meyer May 2020

Ternary Polar Intermetallics Within The Pt/Sn/R Systems (R = La− Sm): Stannides Or Platinides?, Melissa L. Rhodehouse, Volodymyr Smetana, Chris Celania, Anja-Verena Mudring, Gerd H. Meyer

Ames Laboratory Accepted Manuscripts

Starting generally with a 4:6:3 molar ratio of Pt, Sn, and R (where R = La–Sm), with or without the application of a NaCl flux, seven ternary compounds were obtained as single crystals. The platinides Pt4Sn6R3 (R = La–Nd) crystallize with the Pt4Ge6Pr3 type of structure (oP52, Pnma, a = 27.6–27.8 Å, b = 4.59–4.64 Å, c = 9.33–9.40 Å). With R = Pr, Pt4Sn6Pr3–x (oP52, Pnma, a = 7.2863(3) Å, b = 4.4909(2) Å, c = 35.114(1) Å) is also obtained, which might be considered a ...


Mesoporous Adsorbents For Perfluorinated Compounds, Bertha Lotsi May 2020

Mesoporous Adsorbents For Perfluorinated Compounds, Bertha Lotsi

Electronic Theses and Dissertations

Effective adsorbents for polyfluorinated compounds (PFCs) were successfully prepared. And they were tested in the adsorption of perfluorooctanoic and perfluorooctanesulfonic acids. Bridged silsesquioxanes containing secondary and tertiary amino groups were synthesized by sol-gel condensation of bis[3-(trimethoxysilyl)propyl]amine and bis[3-(methylamino)propyl]-trimethoxysilane in acidic media with surfactants. Obtained materials are mesoporous with a high BET surface area. They combine high structural stability with a high concentration of surface amino groups serving as adsorption sites. Batch adsorption tests demonstrated their extremely high adsorption capacity on PFCs: in some experiments, it reached up to 88% of the adsorbent ...


Immobilization Of Phosphotungstic Acid On Silica Surface For Catalytic Alkylation Of Aromatic Compounds, Anastasia Kuvayskaya May 2020

Immobilization Of Phosphotungstic Acid On Silica Surface For Catalytic Alkylation Of Aromatic Compounds, Anastasia Kuvayskaya

Electronic Theses and Dissertations

Superacidic mesoporous materials containing covalently embedded PTA were synthesized by sol-gel method. Tetraethyl orthosilicate (TEOS) and phosphotungstic acid (PTA) were used as precursors in the synthesis, ionic and nonionic surfactants were used as pore-forming agents, the reaction proceeded in acidic media. TEM images revealed mesoporous structure with embedded PTA clusters. FT-IR spectra of obtained materials contained characteristic bands of PTA at 957 cm-1. Synthesized catalysts had high BET surface area and high concentration of acidic sites. Alkylation of 1,3,5-trimethylbenzene by 1-decene demonstrated high catalytic activity. The catalyst obtained with Pluronic P123 as a template was the most effective ...


Investigating The Presence Of Bpa In Infant Oral Hygiene Products Using Fluorescence Spectroscopy, Kaleigh Casada, Sara Hubbard May 2020

Investigating The Presence Of Bpa In Infant Oral Hygiene Products Using Fluorescence Spectroscopy, Kaleigh Casada, Sara Hubbard

Scholars Day Conference

Bisphenol-A (BPA) is a chemical found in hard plastics. BPA is an endocrine disruptor as it binds to estrogen receptors. This is linked to negative health effects such as cardiovascular disease and developmental issues. Infants and young children are more at risk of these effects because their endocrine systems are not fully developed. For this project, toothbrushes were investigated to determine if they contained BPA. BPA is a fluorescent compound with an excitation wavelength of 278 nm and an emission wavelength of 304 nm, so an FS-5 spectrofluorometer from Edinburgh Instruments was used to determine the presence of BPA in ...


Surface Chemistry And Surface Properties Of Energetic Nitrocellulose (Nc), Henry Grau Apr 2020

Surface Chemistry And Surface Properties Of Energetic Nitrocellulose (Nc), Henry Grau

Seton Hall University Dissertations and Theses (ETDs)

This research describes an investigation into the wettability of nitrocellulose (NC), most importantly to nitroglycerin (NG), which are key components of formulations used to propel military ammunition. NG demonstrates complete wetting of NC and, overtime, NG sweats on the NC surface and leaks out. The leaking out of NG from the solid formulation is a known cause of fires and explosions resulting from storage. The origin of this research is inspired by the need to engineer a solution to leakage problems of energetic plasticizer in NC based propellant. While searching for a viable material for a specific application, we journeyed ...


Crystallographic Facet Selective Her Catalysis: Exemplified In Fep And Nip2 Single Crystals, Bryan Owens-Baird, Juliana P.S. Sousa, Yasmine Ziouani, Dmitri Y. Petrovykh, Nikolai A. Zarkevich, Duane D. Johnson, Yury V. Kolen'ko, Kirill Kovnir Apr 2020

Crystallographic Facet Selective Her Catalysis: Exemplified In Fep And Nip2 Single Crystals, Bryan Owens-Baird, Juliana P.S. Sousa, Yasmine Ziouani, Dmitri Y. Petrovykh, Nikolai A. Zarkevich, Duane D. Johnson, Yury V. Kolen'ko, Kirill Kovnir

Ames Laboratory Accepted Manuscripts

How the crystal structures of ordered transition-metal phosphide catalysts affect the hydrogen-evolution reaction (HER) is investigated by measuring the anisotropic catalytic activities of selected crystallographic facets on large (mm-sized) single crystals of iron-phosphide (FeP) and monoclinic nickel-diphosphide (m-NiP2). We find that different crystallographic facets exhibit distinct HER activities, in contrast to a commonly held assumption of severe surface restructuring during catalytic activity. Moreover, density-functional-theory-based computational studies show that the observed facet activity correlates well with the H-binding energy to P atoms on specific surface terminations. Direction dependent catalytic properties of two different phosphides with different transition metals, crystal structures, and ...


Flux Growth Of Phosphide And Arsenide Crystals, Jian Wang, Philip Yox, Kirill Kovnir Apr 2020

Flux Growth Of Phosphide And Arsenide Crystals, Jian Wang, Philip Yox, Kirill Kovnir

Ames Laboratory Accepted Manuscripts

Flux crystal growth has been widely applied to explore new phases and grow crystals of emerging materials. To accommodate the needs of high-quality single crystals, the flux crystal growth should be reliable, controllable, and predictable. The selections of suitable flux and growth conditions remain empirical due to the lack of systematic investigation especially for reactions, which involve highly volatile components, such as P and As. Considering the flux elements, often the system in question is a quaternary or a higher multinary system, which drastically increases complexity. In this manuscript, on the examples of flux growth of phosphides and arsenides, guidelines ...


Crystallization At Droplet Interfaces For The Fabrication Of Geometrically Programmed Synthetic Magnetosomes, Matthew Gromowsky, Michael Stoller, Maddee Rauhauser, Marcus Judah, Abhiteja Konda, Christopher Jurich, Stephen Morin Apr 2020

Crystallization At Droplet Interfaces For The Fabrication Of Geometrically Programmed Synthetic Magnetosomes, Matthew Gromowsky, Michael Stoller, Maddee Rauhauser, Marcus Judah, Abhiteja Konda, Christopher Jurich, Stephen Morin

UCARE Research Products

Many organisms rely on the precise growth, assembly, and/or organization of inorganic crystals to achieve vital functions, for example, three-dimensional structural support (i.e., skeletal systems based on calcite) or environmental sensing (i.e., magnetosomes based on magnetite). Mimicking the production of the complex products observed in these biomineralization processes, synthetically, remains challenging. Herein, a method for the synthesis of artificial magnetosomes with programmable magnetic domains was developed. Specifically, precursors were compartmentalized inside different surfactant-stabilized aqueous-phase droplets suspended in oil and microfluidic technologies were implemented to control their interactions precisely. When reactive droplets were brought into contact with one ...


Intermetallic Nanocatalysts From Heterobimetallic Group 10–14 Pyridine-2-Thiolate Precursors, Carena L. Daniels, Megan Knobeloch, Philip Yox, Marquix A.S. Adamson, Yunhua Chen, Rick W. Dorn, Hao Wu, Guoquan Zhou, Huajun Fan, Aaron J. Rossini, Javier Vela Mar 2020

Intermetallic Nanocatalysts From Heterobimetallic Group 10–14 Pyridine-2-Thiolate Precursors, Carena L. Daniels, Megan Knobeloch, Philip Yox, Marquix A.S. Adamson, Yunhua Chen, Rick W. Dorn, Hao Wu, Guoquan Zhou, Huajun Fan, Aaron J. Rossini, Javier Vela

Chemistry Publications

Intermetallic compounds are atomically ordered inorganic materials containing two or more transition metals and main-group elements in unique crystal structures. Intermetallics based on group 10 and group 14 metals have shown enhanced activity, selectivity, and durability in comparison to simple metals and alloys in many catalytic reactions. While high-temperature solid-state methods to prepare intermetallic compounds exist, softer synthetic methods can provide key advantages, such as enabling the preparation of metastable phases or of smaller particles with increased surface areas for catalysis. Here, we study a generalized family of heterobimetallic precursors to binary intermetallics, each containing a group 10 metal and ...


The Surface Termination Of Cspbbr3 Perovskite Quantum Dots Determined By Solid-State Nmr Spectroscopy, Yunhua Chen, Sara R. Smock, Anne H. Flintgruber, Frederic A. Perras, Richard L. Brutchey, Aaron J. Rossini Mar 2020

The Surface Termination Of Cspbbr3 Perovskite Quantum Dots Determined By Solid-State Nmr Spectroscopy, Yunhua Chen, Sara R. Smock, Anne H. Flintgruber, Frederic A. Perras, Richard L. Brutchey, Aaron J. Rossini

Chemistry Publications

Cesium lead halide perovskite quantum dots (QDs) have gained significant attention as next-generation optoelectronic materials; however, their properties are highly dependent on their surface chemistry. The surfaces of cuboidal CsPbBr3 QDs have been intensively studied by both theoretical and experimental techniques, but fundamental questions still remain about the atomic termination of the QDs. The binding sites and modes of ligands at the surface remain unproven. Herein, we demonstrate that solid-state NMR spectroscopy allows the unambiguous assignments of organic surface ligands via 1H, 13C, and 31P NMR. Surface-selective 133Cs solid-state NMR spectra show the presence of an additional 133Cs NMR signal ...


Identifying The Molecular Edge Termination Of Exfoliated Hexagonal Boron Nitride Nanosheets With Solid-State Nmr Spectroscopy And Plane-Wave Dft Calculations, Rick W. Dorn, Matthew J. Ryan, Tae-Hoon Kim, Tian Wei Goh, Patrick M. Heintz, Lin Zhou, Wenyu Huang, Aaron J. Rossini Feb 2020

Identifying The Molecular Edge Termination Of Exfoliated Hexagonal Boron Nitride Nanosheets With Solid-State Nmr Spectroscopy And Plane-Wave Dft Calculations, Rick W. Dorn, Matthew J. Ryan, Tae-Hoon Kim, Tian Wei Goh, Patrick M. Heintz, Lin Zhou, Wenyu Huang, Aaron J. Rossini

Chemistry Publications

Hexagonal boron nitride nanosheets (h-BNNS), the isoelectronic analog to graphene, have received interest over the past decade due to their high thermal oxidative resistance, high bandgap, catalytic activity, and low cost. The functional groups that terminate boron and nitrogen zigzag and/or armchair edges directly affect their chemical, physical, and electronic properties. However, an understanding of the molecular edge termination present in h-BNNS is lacking. Here, high-resolution magic-angle spinning (MAS) solid-state NMR (SSNMR) spectroscopy, and plane-wave density-functional theory (DFT) calculations are used to determine the molecular edge termination in exfoliated h-BNNS. 1H → 11B cross-polarization MAS (CPMAS) SSNMR ...


Mechanochemical Synthesis, Luminescent And Magnetic Properties Of Lanthanide Benzene-1,4-Dicarboxylate Coordination Polymers (Ln0.5gd0.5)2 (1,4-Bdc)3(H2o)4; Ln = Sm, Eu, Tb, Tarek Alammar, Ihor Hlova, Shalabh Gupta, Anis Biswas, Tao Ma, Lin Zhou, Viktor Balema, Vitalij K. Pecharsky, Anja-Verena Mudring Feb 2020

Mechanochemical Synthesis, Luminescent And Magnetic Properties Of Lanthanide Benzene-1,4-Dicarboxylate Coordination Polymers (Ln0.5gd0.5)2 (1,4-Bdc)3(H2o)4; Ln = Sm, Eu, Tb, Tarek Alammar, Ihor Hlova, Shalabh Gupta, Anis Biswas, Tao Ma, Lin Zhou, Viktor Balema, Vitalij K. Pecharsky, Anja-Verena Mudring

Ames Laboratory Accepted Manuscripts

Mechanochemical reactions of benzene-1,4-dicarboxylate (BDC2−) and lanthanide carbonates, Ln2(CO3)3·xH2O (Ln = Sm, Eu, Gd, Tb) yield phase pure lanthanide coordination polymers, (Ln0.5Gd0.5)2(1,4-BDC)3(H2O)4 with Ln = Sm, Eu, Tb, which are isostructural with Tb2(1,4-BDC)3(H2O)4 as confirmed by powder X-ray diffraction and vibrational spectroscopy. Upon excitation with UV light all three compounds display strong emissions, characteristic for the respective optically active lanthanide ion, namely, red for Eu3+, green for Tb3+ and orange-red for Sm3+. In case of the Tb3+-containing compound, the energy difference between the triplet ...


Fundamentals Of Au(111) Surface Dynamics: Coarsening Of 2d Au Islands, Peter M. Spurgeon, King C. Lai, Yong Han, James W. Evans, Patricia A. Thiel Feb 2020

Fundamentals Of Au(111) Surface Dynamics: Coarsening Of 2d Au Islands, Peter M. Spurgeon, King C. Lai, Yong Han, James W. Evans, Patricia A. Thiel

Chemistry Publications

Au(111) surfaces play a central role in many applications, yet studies of fundamental aspects of their dynamics are limited. Thus, using Scanning Tunneling Microscopy (STM) at 300 K, we analyze the coarsening of first-layer 2D Au islands directly on the Au(111) substrate, and also of second-layer 2D Au islands. Specifically, we monitor the decay of Au first-layer islands with areas of about 100-500 nm^2 in the vicinity of larger islands or extended step edges over a period of approximately 40 hours - the relevant time scale for this process. Experimentally observed behavior is captured by analytic theory for ...


Lisi3as6 And Li2sias2 With Flexible Sias2 Polyanions: Synthesis, Structure, Bonding, And Ionic Conductivity, Justin Mark, Kathleen Lee, Maxwell A. T. Marple, Shannon Lee, Sabyasachi Sen, Kirill Kovnir Feb 2020

Lisi3as6 And Li2sias2 With Flexible Sias2 Polyanions: Synthesis, Structure, Bonding, And Ionic Conductivity, Justin Mark, Kathleen Lee, Maxwell A. T. Marple, Shannon Lee, Sabyasachi Sen, Kirill Kovnir

Ames Laboratory Accepted Manuscripts

Two novel ternary phases, LiSi3As6 and Li2SiAs2, have been synthesized and characterized. Both phases have an identical Si : As ratio of 1 : 2 providing insight on how layers of the parent phase SiAs2 accommodate excess electrons from Li cations to form Si–As anionic frameworks. LiSi3As6 exhibits a variety of bonding schemes involving Si–Si and As–As bonds, as well as corner-sharing SiAs4 tetrahedra, while Li2SiAs2 is isostructural to the previously reported Li2SiP2, with adamantane-like Si4As10 units connected into 3D framework. LiSi3As6 and Li2SiAs2 are predicted to be indirect semiconductors which was experimentally confirmed by optical properties characterization. Li2SiAs2 ...


Silica-Supported Organolanthanum Catalysts For C–O Bond Cleavage In Epoxides, Zhuoran Wang, Smita Patnaik, Naresh Eedugurala, J. Sebastián Manzano, Igor I. Slowing, Takeshi Kobayashi, Aaron D. Sadow, Marek Pruski Feb 2020

Silica-Supported Organolanthanum Catalysts For C–O Bond Cleavage In Epoxides, Zhuoran Wang, Smita Patnaik, Naresh Eedugurala, J. Sebastián Manzano, Igor I. Slowing, Takeshi Kobayashi, Aaron D. Sadow, Marek Pruski

Chemistry Publications

Single-site organolanthanum complexes supported on mesoporous silica nanoparticles, La{C(SiHMe2)3}n@MSNs, catalyze the ring-opening hydroboration reaction of aliphatic and styrenic epoxides with pinacolborane (HBpin). The surface-bound complexes, synthesized by reaction of the homoleptic tris(alkyl)lanthanum La{C(SiHMe2)3}3 and SBA-type MSN treated at 700 °C (MSN700), are mostly monopodal ≡SiO—La{C(SiHMe2)3}2 and contain an average of one bridging La↼H—Si per alkyl ligand. This structure was established through a combination of solid-state NMR (SSNMR) experiments, including J-resolved SiH coupling and quantitative 29Si measurements, diffuse reflectance IR, and elemental ...


Shapes Of Fe Nanocrystals Encapsulated At The Graphite Surface, Ann Lii-Rosales, Yong Han, Scott E. Julien, Olivier Pierre-Louis, Dapeng Jing, Kai-Tak Wan, Michael C. Tringides, James W. Evans, Patricia A. Thiel Feb 2020

Shapes Of Fe Nanocrystals Encapsulated At The Graphite Surface, Ann Lii-Rosales, Yong Han, Scott E. Julien, Olivier Pierre-Louis, Dapeng Jing, Kai-Tak Wan, Michael C. Tringides, James W. Evans, Patricia A. Thiel

Chemistry Publications

We describe and analyze in detail the shapes of Fe islands encapsulated under the top graphene layers in graphite. Shapes are interrogated using scanning tunneling microscopy. The main outputs of the shape analysis are the slope of the graphene membrane around the perimeter of the island, and the aspect ratio of the central metal cluster. Modeling primarily uses a continuum elasticity (CE) model. As input to the CE model, we use density functional theory to calculate the surface energy of Fe, and the adhesion energies between Fe and graphene or graphite. We use the shaft-loaded blister test (SLBT) model to ...


Adsorption, Intercalation, Diffusion, And Adhesion Of Cu At The 2h−Mos2 (0001) Surface From First-Principles Calculations, Yong Han, Michael C. Tringides, James W. Evans, Patricia A. Thiel Feb 2020

Adsorption, Intercalation, Diffusion, And Adhesion Of Cu At The 2h−Mos2 (0001) Surface From First-Principles Calculations, Yong Han, Michael C. Tringides, James W. Evans, Patricia A. Thiel

Chemistry Publications

Study of the adsorption of a transition metal on the surface of a layered material and the possible subsequent intercalation into that layered material is of fundamental interest and potential technological importance. In the present work, we choose the transition metal Cu as the adsorbate or intercalant and 2H-MoS2 as the layered material. Energetics are calculated characterizing four of the most basic surface and interfacial phenomena: adsorption, intercalation, diffusion, and adhesion. Using first-principles density functional theory (DFT), we find that intercalating a Cu atom into the van der Waals (vdW) gap below the MoS2 (0001) surface is 0.665 eV ...


Silicene, Siloxene, Or Silicane? Revealing The Structure And Optical Properties Of Silicon Nanosheets Derived From Calcium Disilicide, Bradley J. Ryan, Michael P. Hanrahan, Yujie Wang, Utkarsh Ramesh, Charles K. A. Nyamekye, Rainie D. Nelson, Zhiyan Liu, Chuankun Huang, Bevan Whitehead, Jigang Wang, Luke T. Roling, Emily A. Smith, Aaron J. Rossini, Matthew G. Panthani Jan 2020

Silicene, Siloxene, Or Silicane? Revealing The Structure And Optical Properties Of Silicon Nanosheets Derived From Calcium Disilicide, Bradley J. Ryan, Michael P. Hanrahan, Yujie Wang, Utkarsh Ramesh, Charles K. A. Nyamekye, Rainie D. Nelson, Zhiyan Liu, Chuankun Huang, Bevan Whitehead, Jigang Wang, Luke T. Roling, Emily A. Smith, Aaron J. Rossini, Matthew G. Panthani

Chemistry Publications

Si-nanosheets (Si-NSs) have recently attracted considerable attention due to their potential as next-generation materials for electronic, optoelectronic, spintronic, and catalytic applications. Even though monolayer Si-NSs were first synthesized over 150 years ago via topotactic deintercalation of CaSi2, there is a lack of consensus within the literature regarding the structure and optical properties of this material. Herein, we provide conclusive evidence of the structural and chemical properties of Si-NSs produced by the deintercalation of CaSi2 with cold (~ –30 °C) aqueous HCl, and characterize their optical properties. We use a wide range of techniques, including XRD, FTIR, Raman, solid-state NMR, SEM, TEM ...


In Situ Monitoring Of Catalytic Molecular Transformations On Noble Metal Nanocatalysts Using Surface-Enhanced Raman Spectroscopy, Hui Wang, Qingfeng Zhang, Esteban Villarreal, Hao Jing, Kexun Chen Jan 2020

In Situ Monitoring Of Catalytic Molecular Transformations On Noble Metal Nanocatalysts Using Surface-Enhanced Raman Spectroscopy, Hui Wang, Qingfeng Zhang, Esteban Villarreal, Hao Jing, Kexun Chen

Journal of the South Carolina Academy of Science

Noble metal nanoparticles have long been of tremendous interest in the nanophotonics and nanocatalysis communities owing to their intriguing size- and shape-dependent plasmonic and catalytic properties. The combination of tunable plasmon resonances with superior catalytic activities on the same noble metal nanoparticle, however, has long been challenging because the research on nanoplasmonics and nanocatalysis deals with nanoparticles in two drastically different size regimes. While tunable plasmon resonances are a unique feature of metallic nanoparticles in the sub-wavelength size regime, heterogeneous catalysis requires the use of substrate-supported sub-5 nm nanoparticulate catalysts. In this mini-review article, we share with the readers several ...


Nanoscale Colocalization Of Fluorogenic Probes Reveals The Role Of Oxygen Vacancies In The Photocatalytic Activity Of Tungsten Oxide Nanowires, Meikun Shen, Tianben Ding, Steven T. Hartman, Fudong Wang, Christina Krucylak, Zheyu Wang, Che Tan, Bo Yin, Rohan Mishra, Matthew D. Lew, Bryce Sadtler Jan 2020

Nanoscale Colocalization Of Fluorogenic Probes Reveals The Role Of Oxygen Vacancies In The Photocatalytic Activity Of Tungsten Oxide Nanowires, Meikun Shen, Tianben Ding, Steven T. Hartman, Fudong Wang, Christina Krucylak, Zheyu Wang, Che Tan, Bo Yin, Rohan Mishra, Matthew D. Lew, Bryce Sadtler

Electrical & Systems Engineering Publications and Presentations

Defect engineering is a strategy that has been widely used to design active semiconductor photocatalysts. However, understanding the role of defects, such as oxygen vacancies, in controlling photocatalytic activity remains a challenge. Here, we report the use of chemically triggered fluorogenic probes to study the spatial distribution of active regions in individual tungsten oxide nanowires using super-resolution fluorescence microscopy. The nanowires show significant heterogeneity along their lengths for the photocatalytic generation of hydroxyl radicals. Through quantitative, coordinate-based colocalization of multiple probe molecules activated by the same nanowires, we demonstrate that the nanoscale regions most active for the photocatalytic generation of ...


Filtration Apparatus Design For Oil-Water Separation Using Membranes And Sponges, Alec Jerger Jan 2020

Filtration Apparatus Design For Oil-Water Separation Using Membranes And Sponges, Alec Jerger

Williams Honors College, Honors Research Projects

It can be difficult to separate water and oil emulsions through traditional filtration. Therefore, investigations of filtering using thermo-responsive (TR) polymers, in this case poly(vinyl methyl ether) (PVME), was conducted. It’s hypothesized that below its lower critical solution temperature (LCST), PVME has an affinity for water while oil substances do not. Above the LCST the opposite will be true. To verify this hypothesis, iterations of filtration designs were created to provide optimum control over the parameters to measure flow. The final optimized experimental apparatus was a Chromaflex glass column which was air tight and controlled all parameters besides ...


Design Of Pigments For Use In “Cool” Coatings, Tyler Laughorn Jan 2020

Design Of Pigments For Use In “Cool” Coatings, Tyler Laughorn

Williams Honors College, Honors Research Projects

This project was focused on the development and testing of several novel pigments that exhibit high NIR-reflectance and therefore show potential for use in “cool” coatings. A “cool” coating will reflect more solar radiation than other standard coatings, and so a coated structure would require less energy to keep cool. Four sets of pigments were synthesized: Co1-xMgxCr2O4 (teal), Co0.25Mg0.75Cr2-yAlyO4 (blue), Ti1-x-yNixSbyO2 (yellow), and Cr2-xFexO3 (black). NIR and TSR values were ...


Synthesis Of Au-Ag Alloy Nanoparticles And Characterization Of Nanoparticle-Anthracene Hybrid Materials, Xiang Zhou Jan 2020

Synthesis Of Au-Ag Alloy Nanoparticles And Characterization Of Nanoparticle-Anthracene Hybrid Materials, Xiang Zhou

Master of Chemical Sciences Capstone Projects

In this work, the optical properties of Au-Ag alloys with an anthracene ligand grafter to their surfaces was examined. Structurally and chemically homogeneous Au-Ag alloy NPs were synthesized by a seed-mediated method with the Ag precursor reduced and grown onto the prepared Au seeds. The alloy NPs were formed after inter-diffusion of Au and Ag and protected using oleylamine. Functionalization of the metal NPs with the anthracene-incorporated ligands was conducted via a simple ligand exchange protocol. The morphological information and chemical composition of the resulting NPs were confirmed by transmission electron microscopy and energy dispersive X-ray spectroscopy, respectively. The plasmonic ...


Metal-Oxide Nanostructures Fabricated From Reactive Laser Ablation In Liquid, Mallory G. John Jan 2020

Metal-Oxide Nanostructures Fabricated From Reactive Laser Ablation In Liquid, Mallory G. John

Theses and Dissertations

The development of metal-oxide nanostructures is a growing area due to their applications in diverse fields spanning energy conversion and storage, chemical manufacturing, and en- vironmental technology. This interest in catalytically active nanomaterials has prompted the synthesis and investigation of highly functionalized nanoparticles (NPs), including core- shell, silicate-stabilized, and bi- and multi-metallic nanocomposites. While wet-chemical synthesis methods of metal-oxide nanostructures have led to several morphologies, compositions, and shapes, these syntheses often require high temperatures, toxic solvents or reducing agents, and long reaction times.

Laser synthesis and processing of colloids (LSPC) encompasses both ‘top down’ and ‘bottom up’ approaches to synthesize ...


Identification Of An Ags2 Complex On Ag(110), Peter M. Spurgeon, Da-Jiang Liu, Junepyo Oh, Yousoo Kim, Patricia A. Thiel Dec 2019

Identification Of An Ags2 Complex On Ag(110), Peter M. Spurgeon, Da-Jiang Liu, Junepyo Oh, Yousoo Kim, Patricia A. Thiel

Chemistry Publications

Adsorbed sulfur has been investigated on the Ag(110) surface at two different coverages, 0.02 and 0.25 monolayers. At the lower coverage, only sulfur adatoms are present. At the higher coverage, there are additional bright features which we identify as linear, independent AgS2 complexes. This identification is based upon density functional theory (DFT) and its comparison with experimental observations including bias dependence and separation between complexes. DFT also predicts the absence of AgS2 complexes at low coverage, and the development of AgS2 complexes around a coverage of 0.25 monolayers of sulfur, as is experimentally observed. To our ...


Hypervalent Iodine Compounds With Carboxylate And Tetrazolate Ligands, Avichal Vaish Dec 2019

Hypervalent Iodine Compounds With Carboxylate And Tetrazolate Ligands, Avichal Vaish

Chemistry Theses and Dissertations

In modern organic chemistry, hypervalent (HV) iodine(III) compounds are frequently used as oxidizing agents but application of λ3-iodanes in polymer and material chemistry is still underexplored. This dissertation describes the preparation of dynamic and self-healing materials by employing ligand exchange reactions involving HV iodine(III) compounds of the type ArIL2 (Ar = Aryl, L = ligand, e.g., carboxylate or (pseudo)halide). These compounds can undergo ligand exchange reactions in presence of nucleophiles (Nu-) to form ArINu2. Diacetoxyiodo benzene was successfully employed as a crosslinker to prepare dynamic and self-healing gels derived from carboxylate-containing polymers. Furthermore, advantage ...


Nanosecond, Time-Resolved Shift Of The Photoluminescence Spectra Of Organic, Lead-Halide Perovskites Reveals Structural Features Resulting From Excess Organic Ammonium Halide, Ujjal Bhattacharjee, Long Men, Han Mai, Daniel Freppon, Emily A. Smith, Javier Vela, Jacob W. Petrich Dec 2019

Nanosecond, Time-Resolved Shift Of The Photoluminescence Spectra Of Organic, Lead-Halide Perovskites Reveals Structural Features Resulting From Excess Organic Ammonium Halide, Ujjal Bhattacharjee, Long Men, Han Mai, Daniel Freppon, Emily A. Smith, Javier Vela, Jacob W. Petrich

Chemistry Publications

The effort to drive solution-based perovskite solar cells towards higher efficiency has been considerable, reaching over 24%. Such progress has been made possible by the low-energy barrier to crystallization. The low-energy barrier in the reverse direction, however, also renders them susceptible to dissociation from heat, moisture, and photoexcitation. Consequently, studies that provide information on the stability of perovskites are of considerable importance. It has been reported that perovskite crystals formed using different stoichiometries of the organic precursors and metal halide are equivalent. Our findings, however, suggest that the difference in reaction pathways affects the quality of the final crystal and ...


Highly Reactive Energetic Films By Pre-Stressing Nano-Aluminum Particles, Michael N. Bello, Alan M. Williams, Valery I. Levitas, Nobumichi Tamura, Daniel K. Unruh, Juliusz Warzywoda, Michelle L. Pantoya Dec 2019

Highly Reactive Energetic Films By Pre-Stressing Nano-Aluminum Particles, Michael N. Bello, Alan M. Williams, Valery I. Levitas, Nobumichi Tamura, Daniel K. Unruh, Juliusz Warzywoda, Michelle L. Pantoya

Aerospace Engineering Publications

Energetic films were synthesized using stress altered nano-aluminum particles (nAl). The nAl powder was pre-stressed to examine how modified mechanical properties of the fuel particles influenced film reactivity. Pre-stressing conditions varied by quenching rate. Slow and rapid quenching rates induced elevated dilatational strain within the nAl particles that was measured using synchrotron X-ray diffraction (XRD). An analytical model for stress and strain in a nAl core–Al2O3 shell particle that includes creep in the shell and delamination at the core–shell boundary, was developed and used for interpretation of strain measurements. Results show rapid quenching induced 81% delamination at the ...


Electrochemical Investigation Into The External Failure Modes Of Oil And Gas Pipelines, Maxwell Goldman Dec 2019

Electrochemical Investigation Into The External Failure Modes Of Oil And Gas Pipelines, Maxwell Goldman

Electronic Thesis and Dissertation Repository

Carbon steel is the material of choice for transmission pipelines for the oil and gas industry across the globe due to its mechanical properties, and low cost. Carbon steel is only resistffxidant, and the types of anions present in the exposure environment. Transmission pipelines are coated with non-conductive polymeric coatings and can be protected by cathodic protection in order to mitigate exterior corrosion. The primary goals of this thesis were to determine the role of anions, cathodic charging with hydrogen, and steel microstructure on different failure modes of carbon steel.

The corrosion mechanism of carbon steel in the presence of ...