Chemistry Commons^™

Colorful "Stars" In The Dark, Chao Jing, Yi-Tao Long

Journal of Electrochemistry

Plasmonic nanoparticles such as Au and Ag with localized surface plasmon resonance (LSPR) property exhibit unique scattering and absorption features. The plasmonic scattering and absorption bands are mainly located at visible light region which can be easily applied in visual detections. By modulating the size, shape, and composition of gold and silver colloid solutions, plenty of colorimetric methods have been constructed for the detection of metal ions, biomolecules, and environmental contaminants, etc. For many years, the LSPR-based measurements are implemented in reagent tubes. Since 2000, the plasmon resonance scattering (PRS) light of metal nanoparticles captured by dark-field microscopy enables the …

Recent Advances In Electrochemical Impedance Spectroscopy-Based Pathogenic Bacteria Sensing, Tao Chen, Yuan-Hong Xu, Jing-Hong Li

Journal of Electrochemistry

Pathogenic bacteria have been throwing great threat on human health for thousands of years. Their real-time monitoring is in urgent need as it could effectively halt the spread of pathogenic bacteria and thus reducing the risk to human health. Up till now, diverse technologies such as electrochemistry, optics, piezoelectricity and calorimetry have been developed for bacteria sensing. Therein, electrochemical impedance spectroscopy (EIS)-based sensors show great potential in point-of-care bacterial analysis because of their low-cost, short read-out time, good reproducibility, and portable equipment construction. In this review, we will primarily summarize the typical applications of electrochemical impedance technology in bacteria sensing …

Metal-Organic Frameworks For Electrochemical And Electrochemiluminescent Immunoassay, Xiao-Li Qin, Zi-Ying Zhan, Sara Jahanghiri, Kenneth Chu, Cong-Yang Zhang, Zhi-Feng Ding

Journal of Electrochemistry

Development of ultrasensitive, highly accurate and selective immunosensors is significant for the early diagnosis, screening, and monitoring of diseases. Electrochemical and electrochemiluminescent (ECL) immunoassays have both attracted great attention and become a current research hotspot due to their advantages such as good stability, high sensitivity and selectivity, wide linear range, and good controllability. Metal-organic frameworks (MOFs), as a new class of porous crystalline materials, have been widely applied in electrochemical and ECL immunosensors owing to their large specific surface area, good chemical stability, as well as adjustable pore size and nanoscale framework structures. Various MOF nanomaterials with different properties for …

Boronate Affinity-Assisted Electrochemically Controlled Atrp For Ultrasensitive Electrochemical Aptasensing Of Carcinoembryonic Antigen, Qiong Hu, Shi-Qi Li, Yi-Yi Liang, Wen-Xing Feng, Yi-Lin Luo, Xiao-Jing Cao, Li Niu

Journal of Electrochemistry

As an acidic glycoprotein, carcinoembryonic antigen (CEA) is of great value as a broad-spectrum tumor marker in the differential diagnosis and surveillance of malignant tumors. In this work, we report an electrochemical aptasensor for the ultrasensitive and highly selective detection of CEA, taking advantage of the dual amplification by the boronate affinity-assisted electrochemically controlled atom transfer radical polymerization (BA-eATRP). Specifically, the BA-eATRP-based electrochemical aptasensing of CEA involves the capture of target antigens by nucleic acid aptamers, the covalent crosslinking of ATRP initiators to CEA antigens via the selective interactions between the phenylboronic acid (PBA) group and the cis-diol group of …

An Aptamer-Based Microelectrode With Tunable Linear Range For Monitoring Of K+ In The Living Mouse Brain, Yuan-Dong Liu, Jia-Run Li, Li-Min Zhang, Yang Tian

Journal of Electrochemistry

Potassium ion (K⁺) is widely involved in several physiopathological processes, and its abnormal changes are closely related to the occurrence of brain diseases of cerebral ischemia. In vivo acquirement of K⁺ variation is significant to understand the roles of K⁺ playing in brain functions. A microelectrode based on single-stranded DNA aptamers was developed for highly selective detection of K⁺ in brain, in which the aptamer probes were designed to contain an aptamer part for specific recognition of K⁺, an alkynyl group used for stable confinement of aptamer probe on the gold surface, and …

Scanning Photoelectrochemical Microscopic Study In Photoinduced Electron Transfer Of Supramolecular Sensitizers-Tio2 Thin Films Systems, Sheng-Ya Zhang, Min Yao, Ze Wang, Tian-Jiao Liu, Rong-Fang Zhan, Hui-Qin Ye, Yan-Jun Feng, Xiao-Quan Lu

Journal of Electrochemistry

Crafting charge transfer channels at titanium dioxide (TiO₂) based photoanodes remain a pressing bottleneck in solar-to-chemical conversion technology. Despite the tremendous attempts, TiO₂ as the promising photoanode material still suffers from sluggish charge transport kinetics. Herein, we propose an assembly strategy that involves the axial coordination grafting metalloporphyrin-based photosensitizer molecules (MP) onto the surface-modified TiO₂ nanorods (NRs) photoanode, forming the composite MP/TiO₂ NRs photoelectrode. As expected, the resulted unique MP_B/TiO₂ NRs photoelectrode displays significantly improved photocurrent density as compared to TiO₂ NRs alone and MP_A/TiO₂ NRs photoelectrode. Scanning …

N–((2–Acetylphenyl)Carbamothioyl)Benzamide: Synthesis, Crystal Structure Analysis, And Theoretical Studies, Akin Oztaslar, Hakan Arslan

Karbala International Journal of Modern Science

N–((2–Acetylphenyl)carbamothioyl)benzamide has been synthesized and characterized. The molecular conformation of the investigated compound is stabilized by C16–H16B⋅⋅⋅O2ⁱ (i: 1+x, y, z) intermolecular and C14–H14⋅⋅⋅S1, N2–H2⋅⋅⋅O2, and N2–H2⋅⋅⋅O1 intramolecular H–bonds. All DFT calculations have been implemented at the B3LYP level with the 6–311G(d,p) basis set. The optimized molecular structure parameters have been compared with the experimental one in the solid phase. The energy gap, global chemical reactivity descriptor parameters, MEP, Fukui functions, DoS, NLO, and NBO analysis were also computed and investigated. The intermolecular interactions and their energies are evaluated using Hirshfeld surface and energy framework analyses. To determine …

Methods Of Magneto-Optical Spectroscopy And Analysis For Porphyrins And Polymer Thin-Films, Emigdio E. Turner

Chemistry and Chemical Biology ETDs

This dissertation describes the construction of two high precision magneto-polarimeters for performing Faraday rotation and Magnetic Circular Dichroism (MCD) measurements of polymer thin-films. There is a focus in materials science on the development of thin-film magneto-optically active materials. These materials could allow for the construction of a thin-film optical diode, an important device for next-generation photonic technology. Upon completion of the Faraday rotation spectrometer, two publications were generated from Faraday rotation measurements of novel polymer thin-film materials.

With growing interest by materials scientists in magneto-optically active transition-metal containing materials, an MCD spectrometer was constructed to study these materials. This spectrometer …

Tio2 Crystallization At Room Temperature And Preparation Of Transparent Carbon Counter Electrode For Low-Cost Dye-Sensitized Solar Cells, Muhammad Iqbal Syauqi, Afiten Rahmin Sanjaya, Mohammad Jihad Madiabu, Munawar Khalil, Jarnuzi Gunlazuardi

Makara Journal of Science

We developed a low-cost dye-sensitized solar cell (DSSC) using TiO₂ fabricated via rapid breakdown anodization (RBA) and ultrafast room-temperature crystallization (URTC). The prepared TiO₂ was deposited on a self-made fluorine-doped tin oxide (FTO) conductive glass, and the FTO/TiO₂ system was sensitized using curcumin dye. The DSSC was constructed by sandwiching the FTO/TiO₂/curcumin electrode with an I⁻/I₂ electrolyte and a transparent carbon counter electrode prepared using a liquid–liquid interface system. The characterization results showed that the TiO₂ freshly prepared via URTC was transformed into an anatase crystalline phase, which exhibited a 3.10 …

Development Of Graphene And Graphene Derivative Advanced Functional Additives: Mechanism And Application In Asphalt Formulations And Thermal Interface Management Materials, Dana Pinson

Dissertations

The overarching focus of my research is the use of graphene and graphene derivatives to enhance polymer properties. My first focus area was the prevention of oxidative degradation of asphalt through the incorporation of a graphene oxide (GO) -based nanoparticle filler to enhance oxygen barrier properties. Primary amine terminated polyisobutylene was synthesized via cationic polymerization followed by post polymerization chain end modification in a range of molecular weights and covalently grafted via the primary amine to graphene oxide aerogel (aGO) to create a polyisobutylene grafted graphene oxide (PIB-g-GO) nanoparticle. PIB-g-GO was then mixed into a substitute asphalt matrix at various …

Supramolecular Design Of 3d-Printable Hydrogels For Functional Materials, Miao Tang

Dartmouth College Ph.D Dissertations

Additive manufacturing, more commonly known as 3D-printing, is bringing about a grand technological transformation in material design and fabrication. In contrast to traditional fabrication techniques, 3D-printing features rapid prototyping, complex and customized 3D structural designs, and multi-material integration. Among current 3D-printing systems, direct-ink-writing (DIW) exhibits unique functionalities due to its mild operation conditions and the ability to integrate various organic and inorganic entities. Although supramolecular binding motifs are increasingly utilized in 3D-printing designs, the optimization of 3D-printable inks remains largely empirical. In this thesis, we present two strategies to rationally design supramolecularly crosslinked 3D-printable hydrogels, including (1) micro-crystallization and (2) …

Covalent Adaptable Networks For Wood Coatings, Jachin Boaz Clarke

Materials Engineering

Wood swells and shrinks causing problems with seasonal humidity. Applying thick coatings of reactive finishes based on cross-linked polyurethane, epoxy, or polyesters can slow moisture-vapor exchange. However, the use of thick coatings leads to cracking and crazing sooner than thin finishes. This research proposes the addition of 3.3 mol % triazabicyclodecene, a conventionally used covalent adaptable network catalyst, in a commercially available polyester-based wood coating. The self-healing of the wood coating is tested using DMA stress relaxation and compression molding. The result from DMA renders inconclusive and compression molding indicates the novel wood coating oxidizes at elevated temperatures. The wood …

Sers For The Detection Of Trace Materials, Omari Kirkland

Dissertations, Theses, and Capstone Projects

In this dissertation are presented three projects that contribute to the body of research on SERS in the forensic, heritage, and semiconductor fields. The first project, Charge-Transfer mapping on GaN/Ag, a silver-decorated nanopillar semiconductor substrate fabricated from the GaN is used with the Raman probe Rhodamine 6 G (R6G) to map the effect of the nanofeatures on the CT resonance. The second project, in collaboration with Marco Leona from the Metropolitan Museum of Art, explores the use of AgNIFs to identify colorants used on textile fiber samples from four 19th century works of Japanese art. The final project analyzes the …

The Effect Of The Carbon Nanotubes’ Surface Area On The Morphology And Performance Of Cellulose Acetate Nanocomposite Membranes In Nanofiltration Applications, Nouran Elbadawi

Theses and Dissertations

Population increase and climate change have significantly affected the availability of fresh water for consumption. Studies by UNESCO showed that more than 28% of the world population didn’t have access to clean safe drinking water in 2020. This situation is expected to get more serious over the coming 30 years with the limited availability of natural fresh water sources. The need to find solutions from alternative non-freshwater resources for drinking or irrigation is becoming a necessity. Within the context of desalination technologies, thousands of investigations are conducted to find the cheapest most efficient way of water treatment aiming at expanding …

A Computational Study Of Adsorptive Desulfurization In Metal Organic Frameworks, Kyle Concha

Theses

Fossil fuel usage has been related to several concerns about the environment and human health. One of these concerns is related to fuels containing Organic Sulfur Compounds (OSCs) which upon burning produce hazardous compounds such as SO₂ which contributes to acid rain and affects respiratory health. Removal of these OSCs is an important field of study as it can prevent the production of SO_x compounds. One technique to remove OSCs is Adsorptive Desulfurization (ADS) in which Metal Organic Frameworks (MOFs) are potential candidates to be used as adsorbents. Two archetypal MOFs, HKUST-1 and Cu₃HHTP₂, …

Deep Euteceic Solvents-Assisted Synthesis Of Novel Network Nanostructures For Accelerating Formic Acid Electrooxidation, Jun-Ming Zhang, Xiao-Jie Zhang, Yao Chen, Ying-Jian Fan, You-Jun Fan, Jian-Feng Jia

Journal of Electrochemistry

Deep eutectic solvents (DESs) have been reported as a type of solvent for the controllable synthesis of metal nanostructures. Interestingly, flower-like palladium (Pd) nanoparticles composed of staggered nanosheets and nanospheres are spontaneously transformed into three-dimensional (3D) network nanostructures in choline chloride-urea DESs using ascorbic acid as a reducing agent. Systematic studies have been carried out to explore the formation mechanism, in which DESs itself acts as a solvent and soft template for the formation of 3D flower-like network nanostructures (FNNs). The amounts of hexadecyl trimethyl ammonium bromide and sodium hydroxide also play a crucial role in the anisotropic growth and …

Fe Nanoparticles Encapsulated In N-Doped Porous Carbon For Efficient Oxygen Reduction In Alkaline Media, Chun-Yan Li, Rui Zhang, Xiao-Jie Ba, Xiao-Le Jiang, Yao-Yue Yang

Journal of Electrochemistry

Rational design and synthesis of non-precious-metal catalyst plays an important role in improving the activity and stability for oxygen reduction reaction (ORR) but remains a major challenge. In this work, we used a facile approach to synthesize iron nanoparticles encapsulated in nitrogen-doped porous carbon materials (Fe@N-C) from functionalized metal-organic frameworks (MOFs, MET-6). Embedding Fe nanoparticles into the carbon skeleton increases the graphitization degree and the proportion of graphitic N as well as promotes the formation of mesopores in the catalyst. The Fe@N-C-30 catalyst showed the excellent ORR activity in alkaline solutions (E₀ = 0.97 V vs. RHE, E_{1/2 …}

P-Doped Ru-Pt Alloy Catalyst Toward High Performance Alkaline Hydrogen Evolution Reaction, Rong-Qin Huang, Wei-Ping Liao, Meng-Xuan Yan, Shi Liu, Yuan-Ming Li, Xiong-Wu Kang

Journal of Electrochemistry

Electrocatalytic water splitting represents grand promise for hydrogen fuel in modern energy equipment, and the design and fabrication of higher performance catalysts are at the central. Herein, we report the sequential phosphorus (P)-doping into ruthenium (Ru) nanoparticles (Ru-P/C) by thermal annealing of Ru nanoparticles in phosphine (PH₃) atmosphere and deposition of extremely low concentration of platinum (Pt) to obtain P-doped Ru-Pt alloy catalyst supported on carbon nanotubes (CNTs), which is denoted as (Ru-P)#Pt/C. The data by X-ray diffraction spectroscopy and transmission electron microscopy show that the Ru nanoparticles existed in the form of hexagonal close-packed (hcp) phase with …

Photophysical And Photochemical Processes In Small Molecules And Materials For Solar Energy Conversion, Ethan Lambert

Honors Theses

The work covered in this thesis all falls under the theme of photophysical processes after light and matter interact. Those of primary interest are Raman scattering induced vibrations and excited state dynamics probed by transient absorption spectroscopy. Small molecules are studied with Raman spectroscopy and computational chemistry. These studies unearth the shifts in vibrational frequency as a function of charge transfer or receipt and how a quantitative assay of natural orbital populations and delocalization can offer both the nature and magnitude of this charge transfer. Further, a method is presented that builds upon previous work within the academic family tree; …

Diffusion Of Ionic Liquid-Modified Polymer Nanoparticles Through Nasal Mucus, Mary Vanlandingham

Honors Theses

Mucosal barriers are a natural defense system for preventing the entry of foreign objects into the body; however, they pose as obstacles for effective drug delivery. Coated polymer nanoparticles have been proven to possess improved rates of diffusion across mucus compared to their uncoated, or bare, counterparts. When choline-based ionic liquids (ILs) are introduced to an aqueous system, their dissociation leads to an increase in solution conductivity which ultimately reduces the viscosity of mucus without significantly affecting its structure. Additionally, ILs are highly tunable, so they work well in a range of pHs and conductivities, making ILs an ideal choice …

A Synthetic Approach To The Optimization Of Silicon-Rosindolizine Swir Fluorophores, Timothy Lewis

Honors Theses

Fluorophores emitting within the near-infrared (700 – 1000 nm) or shortwave-infrared (1000 – 1700 nm) regions of the electromagnetic spectrum are of particular interest for their potential to supplement or even outright replace commonly used biological imaging techniques, such as magnetic resonance imaging and computed tomography scanning. Various characteristics make these molecules particularly appealing to researchers, such as their ease of synthetic tunability, generally low toxicity, and high solubility in biological media in comparison to other NIR- and SWIR-emissive fluorophores. Different molecular skeletons have been examined for use as the core of these imaging agents, such as squaraine, cyanine, and …

Synthesis And Characterization Of Sodium Cathode Materials, He Zhou

McKelvey School of Engineering Graduate Student Theses & Dissertations

As sodium batteries hold great promise as a next-generation energy storage device to replace lithium batteries, the development of sodium battery materials has become increasingly urgent. The current study aims to investigate two potential sodium-ion battery cathode materials, Sodium Vanadium Phosphate, and Sodium Manganese Hexacyanoferrate, optimize the experimental procedures, conduct a systematic analysis of material properties and characterization, and ultimately determine the ideal synthesis conditions for these materials.

In the first part of the study, we focused on optimizing the synthesis of Sodium Vanadium Phosphate. By investigating various synthesis conditions, such as annealing temperature, pressure, ascorbic acid content, and material …

Evaluation Of Promising Eco-Friendly Flame Retardants For Bio-Based Rigid Polyurethane Foams Based On Modified Castor Oil, Prasadi Abeysinghe Arachchilage

Electronic Theses & Dissertations

Fossil fuel derivatives in the polyurethane industry are gradually being replaced with environmentally friendly alternative bio-based resources. Vegetable-oil-based polyols are emerging bio-based resources that can decrease cost competitiveness in polyurethane markets, reduce environmental impacts, and meet the urgent need for green and sustainable development strategies. Among this, interest is the use of castor oil to make polyurethane because of its inedibility and the fact that it contains many functionalizable chemical groups. However, the poor thermal stability and low load-bearing capacity of castor-oil-based rigid polyurethane foam limits its application. Two methods were used to address these limitations: (i) more hydroxyl groups …

Electrochemical Properties Of Mof-Derived Nickel Compounds For High-Performance Supercapacitors And Electrocatalysts, Shiva Bhardwaj

Electronic Theses & Dissertations

There are various forms in which humans use energy in daily life. From applications that require a high energy density to long-term storage, the requirements for energy usage are diverse. Therefore, with the continuous increase in users worldwide, more practical energy-driven sources are required, allowing manufacturers to look toward emerging functional materials. An emerging class of functional porous materials referred to as metal-organic framework (MOF) has received considerable attention over the past two decades, partially because of their potential use in various applications, including gas storage, molecular separations, electrocatalyst, and energy devices. For example, metal oxide and hydroxide-based MOF materials …

Halide Substitution Of Ternary Bismuth Chalcogenides For Photovoltaic Applications, Thomas Boggess

Theses and Dissertations

Semiconductors play an integral part in modern society. From computing to LEDs their use is ubiquitous, and no field is more reliant on them than that of power generation. Current political movements have seen a push to decrease reliance on traditional forms of power generation, which relies on fossil fuels, to renewable sources such as solar power. However, current commercial solar panels, based on silicon, are lacking in efficiency, only reaching between 18% and 22% efficiency.¹ In recent years, materials called perovskites have been garnering significant attention as possible replacements for silicon cells due to their favorable optoelectronic properties. …

Halide Exchange And Transport In Halide Perovskite Lattices, Temban Acha Billy

Department of Chemistry: Dissertations, Theses, and Student Research

In recent years, metal-halide perovskites (MHPs) have risen quickly to prominence as promising materials across a variety of fields, from photovoltaics to optoelectronics in general. We show here a facile solution growth for creating a variety of mixed halide MAPbBr_3-xI_x crystals, which we will use to study halide exchange and transport in halide perovskites. We generated a calibration curve between the optical response and chemical composition in mixed Br/I MHPs at room temperature. All mixed Br/I MHP crystals were subjected to measurements of photoluminescence (PL) and Raman spectroscopy. A subset of mixed-halide MHP crystals exhibited multiple emission …

Biosynthesis Of Copper Nanoparticles Using Hylocereus Costaricensis Peel Extract And Their Photocatalytic Properties, Suriati Eka Putri, Netti Herawati, Ahmad Fudhail, Diana Eka Pratiwi, Sumiati Side, Abd Rahman, Susilo Sudarman Desa, Nur Ahmad, Subaer Junaedi, A. Surleva

Karbala International Journal of Modern Science

A green chemistry method was used for the first time to synthesize copper nanoparticles (Cu-NPs) using CuSO4 as a precursor and red dragon fruit (Hylocereus costaricensis) peel wasted extract as a bio-reductor. Cu-NPs produced were then used as a photocatalysts for acid orange 7 (AO7) dyes degradation. The results showed that the smallest average crystallite size of the products ranged from 8.84 - 8.86 nm, and the FCC crystal structure had a surface area of 244.38-278.85 m2g-1. Furthermore, the optimum degradation of AO7 dye occurred at a ratio of 1:3 with a percentage of 81.07% for four cycles. These findings …

Hollow Mn3o4 Nanoparticles For Catalytic Oxidation Of Alkenes In Air, Nathan R. Loutsch

Honors Thesis

Oxidized hydrocarbons (epoxides, alcohols, carboxylic acids, ketones, and aldehydes) have many uses including fuel production, pollution treatment, and chemical synthesis. These compounds can be formed by oxidizing alkenes and alkanes with the assistance of a catalyst. Heterogeneous catalysts have greater recyclability, but traditionally have lower activity and selectivity. Due to the increased relative surface area, nanomaterials can overcome some of the physical limitations. The Hoefelmeyer lab developed a new nanomaterial: hollow Mn3O4 nanoparticles. Sensitive synthetic conditions have been optimized. Due to the increased relative number of edge and corner atoms, the reactive properties of most small nanomaterials increase. Because of …

Excitation Power Dependence Of Blinking In Copper-Indium-Sulfide Quantum Dots, Nicholas Chambers

Physics Undergraduate Honors Theses

Under continuous excitation, quantum dots exhibit random transitions between fluorescent ON states and non-fluorescent OFF states --- a phenomenon known as blinking. A physical description of the mechanism responsible for blinking that applies broadly to many types of quantum dots remains under debate. We study the blinking behavior of the non-toxic CuInS2 quantum dot, a system that has seen little investigation at the single-particle level. In particular, the optical properties of CuInS2 quantum are often improved by adding ZnS to the nanoparticles, but this addition leads to complex structural-optical property relationships that are even less understood. To probe the relationship …

Developing Methods For Pattern Transfer In Photoelectrochemical Lithography, Ashlyn Descarpentrie

Chemistry & Biochemistry Undergraduate Honors Theses

The microprocessor industry has historically been driven by the goal of shrinking devices. To create features small enough to fit on such devices, photolithography has conventionally been used in the micropatterning of noble metal surfaces. Photolithography is a complicated and expensive process that involves a cleanroom, metallization processes, and photoresist. While this investment makes sense for high revenue applications, a number of microelectronic devices do not require nanometer-scale patterned features. Examples of such applications include specific types of antennae, sensing electrodes, and photocatalysts. Photolithography for these devices is thus too costly in both money and energy. The Coridan lab has …