Materials Chemistry Commons^™

Nanoscale Imaging Of Electrocatalytic Nanomaterials By High-Resolution Scanning Electrochemical Microscopy, Xiang Wang

Dissertations, Theses, and Capstone Projects

Numerous insights of the structure–electrochemical activity relationship of nanocatalysts have been obtained by using macroscopic electrochemical measurements over the last several decades. However, signals measured by large electrodes are inevitably averaged out of many nanocatalysts, non-uniformed sizes, uneven morphologies, and multiple crystallographic facets. Over the last ten years, Scanning Electrochemical Microscopy (SECM) has advanced electrochemical measurements toward micro- to nanoscale level at a high spatial resolution. The advantages of using nanoelectrode in SECM include fast mass transfer of reactive species, dominated radial diffusion pattern, small double layer capacitance and small RC constant. In this thesis, high-resolution SECM is applied to …

Structural And Functional Modulation Of Metal-Organic Supercontainers (Moscs) And Their Applications In Supramolecular Catalysis, Shrijana Dc

Dissertations and Theses

Metal-organic supercontainers (MOSCs), a breakthrough development in our laboratory since 2012, have emerged as promising enzyme mimics, showcasing their prowess in encapsulating guest molecules and catalyzing confined chemical reactions. The intrigue surrounding MOSCs stems from their extraordinary traits, encompassing multiple binding domains, high stability, large surface area, tunable pore size, and structural modularity. Primarily comprising sulfonylcalix[4]arenes, divalent metal ions, and carboxylate linkers, MOSCs' quintessential architecture comprises both endo- and exo- nano-cavities, amenable to guest interaction, with geometry and functionality manipulation achievable through precise precursor selection. Nonetheless, early MOSC models exhibit limited reactivity, often necessitating more potent nucleophiles or electrophiles. This …

Synthesis And Application Of Redox-Active Covalent Organic Frameworks In Rechargeable Batteries, Mohammad K. Shehab

Theses and Dissertations

Synthesis and Application of Redox-Active Covalent Organic Frameworks in Rechargeable Batteries

Mohammad K. Shehab

Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States

Abstract

In recent years, lithium-ion batteries (LIBs) have been considered the dominant energy storage devices for portable electronics and electric vehicles due to their high energy density, low self-discharge rate, and long cycle life. In LIBs, the traditional positive electrodes employed are mainly derived from metal-containing inorganic compounds composed of cobalt, iron, nickel, or manganese (LiCoO₂, LiMn₂O₄, and LiFePO₄) coupled with graphite as the negative electrode. Despite …

Development Of An Effective Au:Pd Bimetallic Heterogeneous Catalyst For Oxidative Lignin Depolymerization To Low Molecular Weight Aromatics, Gayan P. Karunasinghe

Theses and Dissertations--Chemistry

The principal concept behind biorefining involves the transformation of lignocellulosic biomass into valuable products and energy resources. Historically, biorefinery strategies for lignocellulosic biomass have primarily focused on improving the conversion of cellulose into ethanol, often neglecting the underutilized lignin component. Lignin consists of phenolic subunits, from which it follows that value-added products can be obtained from lignin depolymerization. Unfortunately, lignin utilization is particularly challenging due to its high structural irregularity and recalcitrance. The goal of this study was to develop an AuPd/Li-Al layered double hydroxide (LDH) bimetallic catalyst for efficient lignin depolymerization, resulting in the production of high-value aromatic compounds. …

The Application Of Photoelectron Spectroscopies In Analyzing The Impact Of Interfacial Energetics On Perovskite Solar Cells, Tuo Liu

Theses and Dissertations--Chemistry

In recent years, organic-inorganic metal halide perovskites (HP) have garnered tremendous attention in photovoltaic research. This attention is attributed to their low cost and excellent optoelectronic properties, including large absorption coefficients, tunable bandgaps, long charge-carrier diffusion lengths, and low densities of deep trap states. Inverted p-i-n architecture perovskite solar cells (PSCs) are of intense interest and are generally regarded as more amenable to low-temperature solution processing. Nevertheless, the development of inverted PSCs is lagging the conventional architecture devices. Imperfect energy level alignments and charge carrier recombination, especially at the interface between perovskite and electron transport layers (ETLs), are two main …

Material Analysis And Conservation Treatment Of Louise Nevelson’S Sculpture Dawn’S Image, Night, Kaela Nurmi

Art Conservation Master's Projects

Louise Nevelson’s large-scale, matte black assemblage sculpture Dawn’s Image, Night, 1969, is owned by and currently on display at SUNY Buffalo State College. The paint layers exhibited significant amounts of dust, some damages, vandalism, and unsightly fingerprints. Extensive scientific analysis and archival research were utilized to design an appropriate treatment and long-term preservation plan. Methods of analysis include: Fourier transform infrared spectroscopy, pyrolysis-gas chromatography-mass spectrometry, microchemical testing, and xray fluorescence spectroscopy. The project also addresses the ethical considerations surrounding the prior removal of original components for safety considerations, repainting as a possible treatment, and the overall obstacles of treating a …

Sensitized Photooxidation Of Prenylated Compounds: Mechanisms Of Downstream Dark Effects And Phototoxicity Priming, Shakeela Jabeen

Dissertations, Theses, and Capstone Projects

This thesis consists of four chapters as detailed below.

Chapter 1 discusses a singlet oxygen priming mechanism. Airborne singlet oxygen derived from photosensitization of triplet dioxygen is shown to react with an alkene surfactant (8-methylnon-7-ene-1 sulfonate) leading to ‘ene’ hydroperoxides that in the dark inactivate planktonic E. coli. The ‘ene’ hydroperoxide photoproducts are not toxic on their own, but they become toxic after the bacteria are pretreated with singlet oxygen. The total quenching rate constant (k_T) of singlet oxygen of the alkene surfactant was measured to be 1.1 × 10⁶ M⁻¹ s^{− …}

A Novel Electrochemical Sensor Based On Au/Rgo/Feooh For One-Step Detection Of Nitrite, Da-Juan Luo, Bing-Qian Liu, Meng-Yan Qin, Rong Gao, Li-Xia Su, Yong-Huan Su

Journal of Electrochemistry

Nitrite, a widespread raw material, is harmful to human health for long-term consumption. At present, the detection methods of nitrite mainly include chemical analysis, fluorescence, ultraviolet spectrophotometry and chromatography. These methods have ideal sensitivity and selectivity, but also have some characteristics: cumbersome operation, expensive equipment and professional personnel. Therefore, the development of a simple and sensitive nitrite assay is of great significance. In this paper, the Au/rGO/FeOOH composite materials, which revealed good synergistic catalytic performance among the three elements in the composite, were prepared by simple hydrothermal method and reduction method for the first time with large specific surface area …

Biomaterials: From Scaffold Design To Implant Optimization, Jennifer Marie Armen

Electronic Theses and Dissertations

This work encompasses three individual projects concerning biomaterials and their modifications. Chemically-Induced Cross-Linking of Peptidic Fibrils for Scaffolding Polymeric Particles and Macrophages EAK16-II (EAK) is a self-assembling peptide (SAP) that forms β-sheets and βfibrils through ionic-complementary interactions at physiological ionic strengths. The soft materials can be injected in vivo, creating depots of drugs and cells for rendering pharmacological and biological actions. The scope of the applications of EAK is sought to extend to tissues through which the flow of extracellular fluid tends to be limited. In such anatomical locales the rate and extent of the fibrilization are limited insofar as …

Functionalized Biochar Electrodes For Asymmetric Capacitive Deionization, Hellen Stephanie

Theses and Dissertations

Electrosorption-based capacitive deionization (CDI) has become a viable process for brackish water desalination and defluoridation. In this study, activated Douglas fir biochar is used as a low-cost electrode material with adsorption capacity comparable to activated carbon obtained from biomass precursors. Adding functional groups to the activated biochar enhanced salt removal capacity, providing cation and anion selectivity. The functionalized electrodes were prepared by Nafion, titanium isopropoxide, and p-phenylenediamine treatment, respectively, which introduced sulfonate, titanium dioxide and amine functional groups to the electrode surface. These modification methods are versatile and can be easily performed without sophisticated laboratory environment. Modified biochar electrodes …

Analysis Of The Light Responsive Azobenzene Peptide Nucleic Acid Duplexes, Kat Nguyen

Honors College Theses

Peptide nucleic acids (PNAs) are oligonucleotide analogues in which the sugar-phosphate backbone has been replaced by a pseudopeptide skeleton. Since PNAs use the natural nucleobases (Adenine, Thymine, Cytosine, Uracil, and Guanine) found in either DNA and/or RNA, they are able to hybridize according to Watson-Crick base-pairing to form duplexes. PNA is a promising therapeutic agent because they can function as antigene or antisense chemical agents. To further enhance their utility, we aim to incorporate a photoswitchable moiety using azobenzene. Here, we report the results of the synthesis and purification of a photoswitchable 11 mer PNA along with initial characterization efforts.

Real-Time Monitoring Of Paraquat Photodegradation Using Colloidal Gold Surface Enhanced Raman Spectroscopy, Nathan Wilson

Masters Theses & Specialist Projects

Monitoring chemical reactions in aqueous solution is a challenge because most instrumental techniques either are not suited for the rapid timescales, are not sensitive enough to detect products at low concentrations, or do not have sufficient structure-to-spectrum relationships. Raman spectroscopy is a promising method to monitor reactions, as it is fast, dependent on chemical structure, and has little interference from water. However, Raman scattering is generally very weak. Surface-enhanced Raman spectroscopy (SERS) improves the signal strength of Raman spectroscopy by using a metal surface plasmon, or oscillation of the surface’s electrons, to allow for highly selective and sensitive detection and …

In Situ Characterization Of Electrode Structure And Catalytic Processes In The Electrocatalytic Oxygen Reduction Reaction, Ya-Chen Feng, Xiang Wang, Yu-Qi Wang, Hui-Juan Yan, Dong Wang

Journal of Electrochemistry

As an electrochemical energy conversion system, fuel cell has the advantages of high energy conversion efficiency and high cleanliness. Oxygen reduction reaction (ORR), as an important cathode reaction in fuel cells, has received extensive attention. At present, the electrocatalysts are still one of the key materials restricting the further commercialization of fuel cells. The fundamental understanding on the catalytic mechanism of ORR is conducive to the development of electrocatalysts with the enhanced activity and high selectivity. This review aims to summarize the in situ characterization techniques used to study ORR. From this perspective, we first briefly introduce the advantages of …

In-Situ/Operando57Fe Mössbauer Spectroscopic Technique And Its Applications In Nife-Based Electrocatalysts For Oxygen Evolution Reaction, Jafar Hussain Shah, Qi-Xian Xie, Zhi-Chong Kuang, Ri-Le Ge, Wen-Hui Zhou, Duo-Rong Liu, Alexandre I. Rykov, Xu-Ning Li, Jing-Shan Luo, Jun-Hu Wang

Journal of Electrochemistry

The development of highly efficient and cost-effective electrocatalysts for the sluggish oxygen evolution reaction (OER) remains a significant barrier to establish effective utilization of renewable energy storage systems and water splitting to produce clean fuel. The current status of the research in developing OER catalysts shows that NiFe-based oxygen evolution catalysts (OECs) have been proven as excellent and remarkable candidates for this purpose. But it is critically important to understand the factors that influence their activity and underlying mechanism for the development of state-of-the-art OER catalysts. Therefore, the development of in-situ/operando characterizations is urgently required to detect key intermediates along …

Recent Advances In Electrical Transport Spectroscopy For The In Situ Measurement Of Electrochemical Interfaces, Zhang-Yan Mu, Meng-Ning Ding

Journal of Electrochemistry

Electrochemical/electrocatalytic technology has played a central role in achieving highly efficient energy conversion and storage. To date, the in-depth electrochemical research begins to require accurate and multi-dimensional information of electrochemical interfaces, which usually relies on the application of in situ characterizations. Electrical transport spectroscopy (ETS) is a newly developed measurement strategy based on chip-platform, and provides in situ information of electrochemical interfaces from a novel perspective due to a signal origin that is fundamentally different from typical spectroscopic and electrochemical techniques. In this tutorial review, the working principle and experimental setup of ETS are described in detail with the demonstration …

Rational Design Of Electrochemical Molecular Probes For Highly Selective And Long-Term Measurement In Vivo, Yue Wang, Li-Min Zhang, Yang Tian

Journal of Electrochemistry

Designing electrochemical interfaces for in vivo analysis of neurochemicals with high selectivity and long-term stability is vital for monitoring dynamic variation and dissecting the complex mechanisms of pathogenesis in living animals. This review focuses on the development of electrochemical interfaces based on rational design of molecular probes for in vivo measurement with high selectivity and high stability from three aspects: (1) Specific recognition probes were rationally designed and created to remarkably improve the selectivity of in vivo analysis in a complicated brain environment. (2) The Au-C≡C functionalized surface was developed to remarkably enhance the stability of molecular assembly, and employed …

A Flexible Enzymeless Glucose Sensor Via Electrodepositing 3d Flower-Like Cos Onto Self-Supporting Graphene Tape Electrode, Jiang Li, Zuo-Peng Li, Yun-Feng Bai, Su-Xing Luo, Yong Guo, Ya-Yan Bao, Rong Li, Hai-Yan Liu, Feng Feng

Journal of Electrochemistry

Three-dimensional (3D) nanostructural Flower-like cobalt sulfide (CoS) on flexible self-supporting graphene tape electrode (GTE) with remarkably electrocatalytic activity toward glucose was successfully prepared by electrodeposition. Structural characterizations revealed that the electrodeposited CoS was highly dispersed on GTE as an active material. The fabricated binder-free and self-standing CoS/GTE shows a good linear response in the range of 0.025 ~ 1.0 mmol·L^-1, reaching a high glucose sensitivity value of 323.3 μA·(mmol·L ^-1)^-1·cm^-2 and a low detection limit of 8.5 μmol·L ^-1 (S/N = 3). Moreover, the as-prepared sensor was well applied for glucose …

Characterization Of Nanoparticles Using Inductively-Coupled Plasma Mass Spectrometry, Jabez D. Campbell

Graduate Theses/Dissertations

Nanomaterials are a relatively new class of materials that have many applications which span a wide host of fields from medical products to consumer products. The possible compositions and forms of nanomaterials are just as varied as the applications. Therefore, a versatile characterization method is needed for researchers and regulators alike to ensure nanomaterials are properly used. Single Particle Inductively Coupled Plasma Mass Spectrometry (SP-ICP-MS) is a functional method that could fill the characterization need in the nanomaterial research field. Using data from both SP-ICP-MS tests and data from literature established characterization methods, the viability of making SP-ICP-MS the standard …

Analysis Of Forensically Relevant Evidence Using Electrochemistry, Spectroscopy, And Mass Spectrometry Tools, Colby Edward Ott

Graduate Theses, Dissertations, and Problem Reports (ETD)

Forensic science relies on the use of multiple techniques in the assessment of evidence to increase the accuracy and reliability of the results. However, with the rapidly changing drug landscape due to the introduction of novel psychoactive substances, many traditional screening methods are no longer sensitive or selective enough for use. Additionally, many screening methods such as chemical color tests are prone to false positive and negative results and are subjective. Therefore, the goal of this dissertation was to develop a novel analytical scheme that can provide a more efficient, rapid, and sensitive method that will facilitate adoption in the …

Establishing The Relative Composition Of Functionalized Thiols In Mixed Ligand Gold Nanoparticles By 1h-Nmr Spectroscopy, Matthias Carroll

All Master's Theses

Functionalized gold nanoparticles (AuNPs) are of interest for their optical and electrical properties, specifically the surface plasmon resonance phenomenon and potential applications for medicine and nano-circuitry. In this study, the ligand composition of small (~5 nm diameter) thiol functionalized AuNPs with mixed ligand monolayers was investigated to better understand how the molar feed ratio of ligands used during their synthesis influences the composition of ligands on the particle’s surface. The system under study was a combination of two ω-functionalized thiols, mercapto ethoxy ethoxy ethanol (MEEE) and mercapto pentyl trimethyl ammonium chloride (MPTMA). UV/Visible spectrophotometry, dynamic light scattering, and electron …

Photoelectrochemical Sensing Based On Zr-Mofs For Homocysteine Detection, Wen-Xia Dong, Guang-Ming Wen, Bin Liu, Zhong-Ping Li

Journal of Electrochemistry

Due to the independent form of the light source and detection system, photoelectrochemical (PEC) sensor has the advantages of low background, high sensitivity and simple operation. So far, PEC systems have been widely used in the fields including the actual detection of metal ions, biological antibodies or antigens in environmental pollutants. When the photosensitive material is irradiated by a light source with an energy being equal to or greater than its band gap, electrons (e^-) transition occurs from the valence band to the conduction band, leaving a hole (h⁺), at the same time, the generated electron-hole …

Structure Analysis Of Pemfc Cathode Catalyst Layer, Rui-Qing Wang, Sheng Sui

Journal of Electrochemistry

The sluggish oxygen reduction reaction (ORR) on the cathode of the proton exchange membrane fuel cell (PEMFC) has always been one of the key factors limiting its commercialization. The optimization of the cathode catalytic layer structure plays an important role in improving fuel cell performance and reducing production costs. In this paper, two different catalysts (platinum nanoparticles (Pt-NPs) and platinum nanowires (Pt-NWs)) were prepared by using catalyst coated substrate (CCS) method. By constructing a double-layer catalytic layer structure, we analyzed the effect of different catalytic layer structures by performing a single cell test. The results showed that the dense platinum …

Investigating Thermodynamics And Kinetics Of Methylene Blue And Eriochrome Black-T Adsorption On Activated Carbon Prepared From Coconut Husk, Abdul Rahman Wahoud, Lotfi Abdul Samed Bawazer

Hadhramout University Journal of Natural & Applied Sciences

In this research, the adsorption process was studied for methylene blue eriochrome black-T from aqueous solutions on the surface of activated carbon prepared from coconut husk by chemical activation with potassium hydroxide. The results show that the adsorption isotherm for methylene blue follows the Langmuir model while it follows the Freundlich model and the maximum adsorption capacity was 909 mg/g for methylene blue and 262 mg/g for eriochrome black-T. The equilibrium contact time reached in about 90 minutes at lower concentrations and 120 minutes at higher concentrations. Two simplified kinetic models including pseudo-first-order and pseudo-second-order equations were selected to follow …

Mathematical Expression And Quantitative Analysis Of Impedance Spectrum On The Interface Of Glassy Carbon Electrode, Lei Cheng, Pu-Xuan Yan, You-Jun Fan, Hua-Hong Zou, Hong Liang

Journal of Electrochemistry

Glassy carbon electrode (GCE) is a common basic electrode for various electrochemical sensors, and the detection properties are determined by its interfacial characteristics. In this paper, we established an equivalent circuit including electrolyte resistance (R_el), charge transport resistance (R_ct), diffusion impedance (R_di, C_di), electrochemical (oxidation/reduction) reaction impedance (R_R, C_R), surface adsorption impedance (R_ads , C_ads), double-layer capacitance (C_DL), and derived the mathematical expression for the equivalent circuit. The R_el and C_DL are contributed by inactive …

Preparation Of Modified Titanium Based Pbo2 Electrode And Its Rapid Detection Of Cod, Qi Sun, Yan-He Han, Xiao-Lu Fu

Journal of Electrochemistry

In the traditional Ti/β-PbO₂ electrode, the crystal lattice difference between β-PbO₂ and Ti matrix is large, and the prepared electrode is easy to fall off and has a short service life. It needs to be modified in actual use. Based on the advantages of α-PbO₂ material and Ag material in terms of adhesion and conductivity, respectively, the above two materials are selected as the intermediate layer of Ti/β-PbO₂ electrode to improve electrode performance. In this paper, by preparing Ti/α/β-PbO₂ and Ti/Ag/β-PbO₂ electrodes …

Fundamentals Of Electrochemical Impedance Spectroscopy For Macrohomogeneous Porous Electrodes, Xiang Li, Qiu-An Huang, Wei-Heng Li, Yu-Xuan Bai, Jia Wang, Yang Liu, Yu-Feng Zhao, Juan Wang, Jiu-Jun Zhang

Journal of Electrochemistry

Electrochemical impedance spectroscopy (EIS) can be used to diagnose charge transfer reactions and mass transport in porous electrodes. The charge transfer reactions include interfacial charge accumulation and charge conduction as well as electrochemical reaction. In this paper, the complex phasor method is developed under the macrohomogeneous assumption to build an impedance model of porous electrodes for clarifying several vague expressions in the traditional approaches. The following researches are carried out: (1) Identifying characteristic parameters for the porous electrodes, including electrode electronic conductivity σ₁, electrolyte ionic conductivity σ₂, interface charge transfer conductivity g_ct, unit area …

Hemoglobin-Modified Core–Shell Fe3o4@Au Nanostructures For The Electrochemical Detection Of Acrylamide, Endang Saepudin, Tri Yuliani, Mochammad Arfin Fardiansyah Nasution, Munawar Khalil, Jong Wook Hong, Tribidasari Anggraningrum Ivandini

Makara Journal of Science

In this study, electrochemical detection of acrylamide using hemoglobin (Hb)-modified core–shell Fe₃O₄@Au nanostructures was conducted. Fe₃O₄ nanoparticles (~4.9 nm) and core–shell Fe₃O₄@Au (5.0–6.4 nm) nanostructures were successfully synthesized by the thermal decomposition method. Electrochemical investigation revealed that the optimum amount of Hb of 2 mg/mL could be immobilized in 0.1 M acetate buffer solution (pH = 6). Moreover, the detection of acrylamide using Fe₃O₄@Au/Hb was evaluated by the cyclic voltammetry technique. A linear calibration curve (R² = 0.98) in the concentration range of …

Two-Dimensional Monolayer Salt Nanostructures Can Spontaneously Aggregate Rather Than Dissolve In Dilute Aqueous Solutions, Wenhui Zhao, Yunxiang Sun, Weiduo Zhu, Jian Jiang, Xiaorong Zhao, Dongdong Lin, Wenwu Xu, Xiangmei Duan, Joseph S. Francisco, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

It is well known that NaCl salt crystals can easily dissolve in dilute aqueous solutions at room temperature. Herein, we reported the first computational evidence of a novel salt nucleation behavior at room temperature, i.e., the spontaneous formation of two-dimensional (2D) alkali chloride crystalline/non-crystalline nanostructures in dilute aqueous solution under nanoscale confinement. Microsecond-scale classical molecular dynamics (MD) simulations showed that NaCl or LiCl, initially fully dissolved in confined water, can spontaneously nucleate into 2D monolayer nanostructures with either ordered or disordered morphologies. Notably, the NaCl nanostructures exhibited a 2D crystalline square-unit pattern, whereas the LiCl nanostructures adopted non-crystalline 2D hexagonal …

Doping Of Conjugated Polymers: Preparation, Characterization And Device Fabrication, Kan Tang

Dissertations

Semiconducting conjugated polymers (CPs) as emerging materials for advanced electronic applications such as sensors, OPVs, and OEFTs has become an intriguing research topic in the past decades. It opens a new avenue of “flexible” electronics, which has shown great potential in next-generation electronic devices.

However, due to the nature of CP materials and related solution processing techniques, unlike almost perfectly crystalline silicon materials, CPs in the solid-state often exhibit much lower crystallinity if it is not complete amorphous, which severely hinder the electronic property and optical property of the materials. The crystallinity of CPs in a film is often uniquely …

Degumming Of Hemp Fibers Using Combined Microwave Energy And Deep Eutectic Solvent, Bulbul Ahmed

LSU Master's Theses

Hemp is considered as one of the sustainable agricultural fiber materials. Degumming or surface modification of hemp bast is needed to produce single fibers for ensuing textile and industrial applications. The traditional degumming process necessitates a high amount of alkali, which causes detrimental environmental pollution. This study offers a new method to degum hemp fibers with reduced use of harmful alkali and precious water resources. In this work, hemp bast fibers were degummed by using combined microwave energy and deep eutectic solvent (DES). The properties of hemp fibers manufactured by this method were investigated and compared with the traditional alkali …