Physics Commons^™

Mechanistic Investigation Of C—C Bond Activation Of Phosphaalkynes With Pt(0) Complexes, Roberto M. Escobar, Abdurrahman C. Ateşin, Christian Müller, William D. Jones, Tülay Ateşin

Research Symposium

Carbon–carbon (C–C) bond activation has gained increased attention as a direct method for the synthesis of pharmaceuticals. Due to the thermodynamic stability and kinetic inaccessibility of the C–C bonds, however, activation of C–C bonds by homogeneous transition-metal catalysts under mild homogeneous conditions is still a challenge. Most of the systems in which the activation occurs either have aromatization or relief of ring strain as the primary driving force. The activation of unstrained C–C bonds of phosphaalkynes does not have this advantage. This study employs Density Functional Theory (DFT) calculations to elucidate Pt(0)-mediated C–CP bond activation mechanisms in phosphaalkynes. Investigating the …

Thermocatalytic Plasma-Assisted Dry Reforming Of Methane Over Ni/Al2o3 Catalyst, Tyler Wong

Seton Hall University Dissertations and Theses (ETDs)

Plasma catalysis is an advantageous approach that combines the effects of plasma with the enhancements of a catalyst. By utilizing a nickel catalyst in the plasma discharge zone of a dielectric barrier discharge (DBD), it can give an enhancement to the electrical field, boost microdischarges, and increase conversion and selectivity rates of CH₄ and CO₂ in the dry reforming of methane (DRM) reaction.

Industrial application of nickel catalysts in DBD Plasma DRM process are limited by poor stability, which is caused by the sintering of active metal particles and coke deposition on the catalyst surface. In this work, …

Computational Study Of The Reactions Of Heteroatomic Compounds On Ceo2, Suman Bhasker Ranganath

LSU Doctoral Dissertations

The mechanisms of ambient-temperature reactions of heteroatomic compounds catalyzed by ceria (CeO₂), an archetypical reducible oxide, for enzyme mimetics, environmental protection, and chemical synthesis are investigated in this dissertation using theoretical methods. CeO₂ is modeled with thermodynamically stable low-index surfaces exposed by commonly studied ceria thin films and nano particles. To understand phosphatase-like dephosphorylation activity, stable adsorption states and surface reactions of model phosphates are examined. Binding of the central P-atom to surface lattice oxygen (O_latt) supplemented by phosphoryl O-Ce interaction is the only stable adsorption state for the un-dissociated molecule. Deprotonation of phosphate monoesters, …

Intramolecular Friedel-Crafts Addition Of Indoles To Tertiary Allylic Alcohols, Bryan H. Wakefield, Romie Barnes, Traeannah Brown, Ashley M. Jones, Victoria A. Knotts, Christina Martinetti

Journal of the South Carolina Academy of Science

An intermolecular Friedel-Crafts alkylation of indole and tertiary allylic alcohols has been developed. The allylic alcohols were synthesized using a two-step procedure, then exposure of these alcohols to diphenyl phosphate facilitated the desired annulation reaction. This reaction tolerated a variety of indole substitutions to yield 1H,2H,3H,4H-pyrido[1,2-a]indoles.

Heterogenous Reduction Of Co2 Over Boron-Rich Alb2, Jose C. Berger

Honors Undergraduate Theses

Evidence suggests that the recent drastic changes in the global climate have been caused by greenhouse gases, especially CO­₂. As a result, scientists are aiming to develop processes that either minimize the production of these gases or convert them into products of higher value. To that end, the catalytic properties of a two-dimensional boron-rich material were investigated. Herein is reported that such a material can reduce CO₂ into benzene, C₃ species, and C₄ species at relatively low temperatures (225-450 ℃) and pressures (0.38 MPa). Current data suggest that a low-temperature induction period (e.g., 225 ℃) …

Computational Design Of Two-Dimensional Transition Metal Dichalcogenide Alloys And Their Applications, John Douglas Cavin

Arts & Sciences Electronic Theses and Dissertations

The discovery of bronze as an alloy of copper and tin is arguably the earliest form of material design, dating back thousands of years. In contrast, two-dimensional materials are new to the 21st century. The research presented in this dissertation is at the intersection of alloying and two-dimensional materials. I specifically study a class of two-dimensional materials known as transition metal dichalcogenides (TMDCs). Because of the large number of transition metals, there are many combinations of TMDCs that can be alloyed, making experimental exploration of the phase space of possible alloys unwieldly. Instead, I have applied first-principles methods to study …

Alternative View Of Oxygen Reduction On Porous Carbon Electrocatalysts: The Substance Of Complex Oxygen-Surface Interactions, Giacomo De Falco, Marc Florent, Jacek Jagiello, Yongqiang Cheng, Luke L. Daemen, Anibal J. Ramirez-Cuesta, Teresa J. Bandosz

Publications and Research

Electrochemical oxygen reduction reaction (ORR) is an important energy-related process requiring alternative catalysts to expensive platinum-based ones. Although recently some advancements in carbon catalysts have been reported, there is still a lack of understanding which surface features might enhance their efficiency for ORR. Through a detailed study of oxygen adsorption on carbon molecular sieves and using inelastic neutron scattering, we demonstrated here that the extent of oxygen adsorption/interactions with surface is an important parameter affecting ORR. It was found that both the strength of O2 physical adsorption in small pores and its specific interactions with surface ether functionalities in the …

Symmetry And Interface Considerations For Interactions On Mos2, Prescott E. Evans

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

The critical role of symmetry, in adsorbate-MoS₂ interactions, has been demonstrated through a variety of electronic structure, topology, and catalytic studies of MoS₂ and MoS₂ composites.A combination of density functional theory and experiment exhibiting diiodobenzene isomer dependent adsorption rates highlight frontier orbital symmetry as key to adsorption on MoS₂. It is clear that the geometry and symmetry of MoS₂ influences the creation and stability of surface defects, that in turn affect catalytic activity and a myriad of other applications. We have shown that surface reactions such the methanol to methoxy reaction can create defects …

Beyond Density Functional Theory: The Multiconfigurational Approach To Model Heterogeneous Catalysis, Samuel J. Stoneburner, Carlo Alberto Gaggioli, Christopher J. Cramer, Laura Gagliardi

Educator Scholarship

Catalytic processes are crucially important for many practical chemical applications. Heterogeneous catalysts are especially appealing because of their high stability and the relative ease with which they may be recovered and reused. Computational modeling can play an important role in the design of more catalytically active materials through the identification of reaction mechanisms and the opportunity to assess hypothetical catalysts in silico prior to experimental verification. Kohn-Sham density functional theory (KS-DFT) is the most used method in computational catalysis because it is affordable and it gives results of reasonable accuracy in many instances. Furthermore, it can be employed in a …

Synergistic Interactions Of H2 And N2 With Molten Gallium In The Presence Of Plasma, Maria L. Carreon, Daniel F. Jaramillo-Cabanzo, Indira Chaudhuri, Madhu Menon, Mahendra K. Sunkara

Physics and Astronomy Faculty Publications

The present study examines the interaction of hydrogen and nitrogen plasmas with gallium in an effort to gain insights into the mechanisms behind the synergetic effect of plasma and a catalytic metal. Absorption/desorption experiments were performed, accompanied by theoretical-computational calculations. Experiments were carried out in a plasma-enhanced, Ga-packed, batch reactor and entailed monitoring the change in pressure at different temperatures. The results indicated a rapid adsorption/dissolution of the gas into the molten metal when gallium was exposed to plasma, even at a low temperature of 100 °C. The experimental observations, when hydrogen was used, indicate that gallium acts as a …

Adsorption Of Co2 Molecule On The (Mgo)9 And (Cao)9 Nanoclusters; A Theoretical Study, Innovative Research Publications Irp India, Fathi Hassan Bawa

Innovative Research Publications IRP India

Binding configurations of CO2 on (MgO)9 and (CaO)9 cluster models are investigated by means of density functional theory model calculations. The results show that CO2 adsorbs as monodentate on MgO and CaO terrace site leads to formation of surface carbonates CO3 2- . Marginal differences in the binding stabilities between the CO2 molecule and surface O2- site were found to be significantly similar. The estimated adsorption energies are 1.47 eV and 1.52 eV at the (MgO)9 and (CaO)9 clusters, respectively. The similarity in binding energies is discussed in terms of cluster electropositivity. Adsorbed CO2, to (MgO)9 surface vibration frequencies are …

Electrostatic Force Microscopy And Electrical Isolation Of Etched Few-Layer Graphene Nano-Domains, D. Patrick Hunley, Abhishek Sundararajan, Mathias J. Boland, Douglas R. Strachan

Physics and Astronomy Faculty Publications

Nanostructured bi-layer graphene samples formed through catalytic etching are investigated with electrostatic force microscopy. The measurements and supporting computations show a variation in the microscopy signal for different nano-domains that are indicative of changes in capacitive coupling related to their small sizes. Abrupt capacitance variations detected across etch tracks indicates that the nano-domains have strong electrical isolation between them. Comparison of the measurements to a resistor-capacitor model indicates that the resistance between two bi-layer graphene regions separated by an approximately 10 nm wide etch track is greater than about 1×10¹² Ω with a corresponding gap resistivity greater than about …

The Metal Ion Requirements Of Arabidopsis Thaliana Glx2-2 For Catalytic Activity, Pattraranee Limphong, Ross M. Mckinney, Nicole E. Adams, Christopher A. Makaroff, Brian Bennett, Michael W. Crowder

Physics Faculty Research and Publications

In an effort to better understand the structure, metal content, the nature of the metal centers, and enzyme activity of Arabidopsis thaliana Glx2-2, the enzyme was overexpressed, purified, and characterized using metal analyses, kinetics, and UV–vis, EPR, and ¹H NMR spectroscopies. Glx2-2-containing fractions that were purple, yellow, or colorless were separated during purification, and the differently colored fractions were found to contain different amounts of Fe and Zn(II). Spectroscopic analyses of the discrete fractions provided evidence for Fe(II), Fe(III), Fe(III)–Zn(II), and antiferromagnetically coupled Fe(II)–Fe(III) centers distributed among the discrete Glx2-2-containing fractions. The individual steady-state kinetic constants varied among the …

Supported Mono And Bimetallic Platinum And Iron Nanoparticles Electronic, Structural, Catalytic, And Vibrational Properties, Jason Robert Croy

Electronic Theses and Dissertations

Catalysis technologies are among the most important in the modern world. They are instrumental in the realization of a variety of products and processes including chemicals, polymers, foods, pharmaceuticals, fuels, and fuel cells. As such, interest in the catalysts that drive these processes is ongoing, and basic research has led to significant advances in the field, including the production of more environmentally friendly catalysts that can be tuned at the molecular/atomic level. However, there are many factors which influence the performance of a catalyst and many unanswered questions still remain. The first part of this work is concerned with the …

In-Situ Gas Phase Catalytic Properties Of Metal Nanoparticles, Luis Ono

Electronic Theses and Dissertations

Recent advances in surface science technology have opened new opportunities for atomic scale studies in the field of nanoparticle (NP) catalysis. The 2007 Nobel Prize of Chemistry awarded to Prof. G. Ertl, a pioneer in introducing surface science techniques to the field of heterogeneous catalysis, shows the importance of the field and revealed some of the fundamental processes of how chemical reactions take place at extended surfaces. However, after several decades of intense research, fundamental understanding on the factors that dominate the activity, selectivity, and stability (life-time) of nanoscale catalysts are still not well understood. This dissertation aims to explore …

Reactivity And Sintering Kinetics Of Au/Tio2(110) Model Catalysts: Particle Size Effects, Stephen C. Parker, Charles T. Campbell

Faculty Work

We review here our studies of the reactivity and sintering kinetics of model catalysts consisting of gold nanoparticles dispersed on TiO2(110). First, the nucleation and growth of vapor-deposited gold on this surface was experimentally examined using x-ray photoelectron spectroscopy and low energy ion scattering. Gold initially grows as two-dimensional islands up to a critical coverage, hcr, after which 3D gold nanoparticles grow. The results at different temperatures are fitted well with a kinetic model, which includes various energetic parameters for Au adatom migration. Oxygen was dosed onto the resulting gold nanoparticles using a hot filament technique. The desorption energy of …

Investigation Of The Catalytic And Structural Roles Of Conserved Histidines Of Human Coproporphyrinogen Oxidase Using Site-Directed Mutagenesis, Shani J. Gitter, Christopher L. Cooper, Jon A. Frieson, Timothy D. Lash, Marjorie A. Jones

Faculty Publications – Chemistry

Background: The catalytic contribution of four conserved histidines of human coproporphyrinogen oxidase (CPO) has been investigated using site-directed mutagenesis to change histidine (H) into alanine (A). Material/Methods: The wild-type and mutant enzyme forms were analyzed for their ability to utilize coproporphyrinogen-III, mesoporphvrinogen-VI, and harderoporphyrinogen as substrates. Results: Wild-type CPO had specific activities of 4.9 +/- 0.9 nmole product/min/mg for coproporphyrinogen-III, 1.7 +/- 0.7 nmole ptoduct/min/mg for mesoporphyrinogen-VI, and 5.1 +/- 1.8 nmole product/min/mg for harderoporphyrinogen. The four mutant enzymes were catalytically competent With all three substrates, but to varying degrees. The most affected Mutant was the H158A enzyme which exhibited …

A Novel Laboratory Course On Advanced Chemical Engineering Experiments, Jochen A. Lauterbach, S. White, X. Lui, G. M. Bodner, W. N. Delgass

Faculty Publications

The chemical engineering curriculum in the United States has trained generations of technical experts who have successfully optimized chemical processes and products once they entered the chemical industry. The U.S. chemical industry, however, has entered a critical stage in which it must be able to create new and differentiated value through technical innovations that arc essential for long-term survival. This innovation process will require new skills that go far beyond the traditional expertise for the optimization of tasks possessed by young chemical engineers. The innovators must be able to identify new opportunities, explore the boundaries of technology, evaluate critical issues, …