Materials Chemistry Commons^™

Designing Metal-Halide Perovskites With Enhanced Optical Properties And Stability Using Surface Ligands, Md Aslam Uddin

Theses and Dissertations--Chemistry

Metal-halide perovskites (MHPs), with formula ABX₃ (A = methylammonium, formamidinium, or Cs⁺; B = Sn²⁺ or Pb²⁺; and X = Cl^-, Br^-, or I^-) are versatile and attractive materials because of their tunable optical and electronic properties. These optical and electronic properties include tunable direct band gaps, high absorption coefficients, low exciton binding energies, relatively high electron and hole mobilities, narrow emission line-widths, and high photoluminescence (PL) quantum yields (Φ_PL). Much of the initial excitement around organic metal-halide perovskites focused on their application in photovoltaics (PVs) …

Developing And Testing Redox Active Organic Molecules For Nonaqueous Redox Flow Battery Applications, Nuwan Harsha Attanayake

Theses and Dissertations--Chemistry

Non-emissive, sustainable energy sources such as solar, wind, and geothermal power have continued to provide an increasing amount of electricity to support electrical grids. Due to the intermittent nature of renewable energy sources like wind and solar, grid energy storage systems must adjust for variations in and mismatches between electricity production and consumption. Among the available energy storage technologies, redox flow batteries (RFBs) are expected to play a critical role in the grid energy storage due to their decoupled energy and power, long service life, and simple manufacturing. However, the worldwide market penetration of RFB systems is still limited due …

Identification Of Adsorbate Ft-Ir Bands Using In-Situ Techniques: Pd Speciation And Adsorption Chemistry Of Pd-Zeolites For Passive Nox Adsorption, Robert Bruce Pace Iii

Theses and Dissertations--Chemistry

To meet increasingly stringent automotive emissions standards, further improvements in catalytic converter design are necessary. Current automotive catalyst systems are effective at eliminating emission of nitrogen oxides (NO_x) once the catalyst reaches operational temperature (~200 °C). NO_x emitted at lower catalyst temperatures now comprises most of the NO_x released during a typical test cycle. Referred to as “the cold start problem” this issue has come to the forefront of automotive catalyst development, as mitigating these emissions is necessary to further reduce automotive emissions. Passive NO_x adsorbers present an appealing solution to the cold start problem, …

Cu(Ii) Phenanthroline-Phenazine Complexes Dysregulate Mitochondrial Function And Stimulate Apoptosis, Garret Rochford, Zara Molphy, Kevin Kavanagh, Malachy Mccann, Michael Devereux, Andrew Kellett, Orla L. Howe

Articles

Herein we report an in-depth study on the cytotoxic mechanism of action of four developmental cytotoxic copper(II) complexes: [Cu(phen)2]2+ (Cu-Phen); [Cu(DPQ)(Phen)]2+ (Cu-DPQ-Phen); [Cu(DPPZ)(Phen)]2+; and [Cu(DPPN)(Phen)]2+ (where Phen = 1,10-phenanthroline, DPQ = dipyrido[3,2-f:20,30-h]quinoxaline, DPPZ = dipyrido[3,2-a:20,30-c]phenazine, and DPPN = benzo[i]dipyrido[3,2-a:20,30-c]phenazine). This complex class is known for its DNA intercalative properties and recent evidence—derived from an in vivo proteomic study—supports the potential targeting of mitochondrial function. Therefore, we focused on mitochondrial-mediated apoptosis related to cytotoxic activity and the potential impact these agents have on mitochondrial function. The Cu(II) complexes demonstrated superior activity regardless of aromatic extension within the phenazine ligand to the …

Electrocatalytic Cathodes For Advanced Lithium–Sulfur Batteries, Ahmed Abdelkader

Theses and Dissertations

Energy demands are anticipated to increase in the next decades with the consumption of fossil fuels predicted to grow from the current levels. This will place an enormous burden on the non–renewable reserves of our energy sources and add to the preexisting environmental crisis with the emission of greenhouse gases like carbon dioxide (CO₂). Electrical energy storage (EES) is considered one of the most crucial needs of modern society to circumvent this crisis and potential applications include electric vehicles and devices, as well as storage systems for solar and wind sources.Lithium–ion batteries (LIBs) have proven to be …

Synthesis Of Supported Metal Nanoparticles On High Surface Area Supports For Application In Energy Conversion And Heterogeneous Catalysis, Nazgol Norouzi

Theses and Dissertations

Precise control of metal nanoparticles’ size, composition, and dispersity over high surface area supports are highly desirable to address current challenges in energy storage and conversion as well as catalytic processes involving precious metals. Therefore, developing viable synthetic routes that enable new catalytic systems derived from inexpensive transition metals or limited use of precious metals is vital for clean energy applications such as fuel cells and rechargeable batteries or affordable drugs in the pharmaceuticals arena. In addition to metal components of heterogeneous catalysts, the catalyst support is an integral part of catalyst design as it can impart both physical stability …

Structure, Morphology And Composition-Property Elucidation Of Ni–Mo And Ni−Mo−P Nanocrystals For Water Splitting Reactions And Group Iv Alloy And Silicate Nanocrystals For Visible To Near Ir Optoelectronics, Ebtesam Hassan Abuelenein Eladgham

Theses and Dissertations

Abstract

Structure, Morphology and Composition-Property Elucidation of Ni–Mo and Ni−Mo−P Nanocrystals for Water Splitting Reactions and Group IV Alloy and Silicate Nanocrystals for Visible to Near IR Optoelectronics

by

Ebtesam Hassan Abuelenein Eladgham

A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Virginia Commonwealth University.

Advisor: Indika U Arachchige

Associate Professor, Department of Chemistry

Nanomaterials have gained a great attention because of their unique physical properties with size intermediate between molecular materials and extended solids. They have a large surface to volume ratio and display size tunable physical properties that was not …

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 …

Synthesis Of Graphene Using Plasma Etching And Atmospheric Pressure Annealing: Process And Sensor Development, Andrew Robert Graves

Graduate Theses, Dissertations, and Problem Reports (ETD)

Having been theorized in 1947, it was not until 2004 that graphene was first isolated. In the years since its isolation, graphene has been the subject of intense, world-wide study due to its incredibly diverse array of useful properties. Even though many billions of dollars have been spent on its development, graphene has yet to break out of the laboratory and penetrate mainstream industrial applications markets. This is because graphene faces a ‘grand challenge.’ Simply put, there is currently no method of manufacturing high-quality graphene on the industrial scale. This grand challenge looms particularly large for electronic applications where the …