Analytical Chemistry Commons^™

Single Particle Impact Electrochemistry: Analyses Of Nanoparticles And Biomolecules, Jian-Hua Zhang, Yi-Ge Zhou

Journal of Electrochemistry

Single particle impact electrochemistry (SPIEC) has grown rapidly in recent years and shown great promise in the analysis of nanoparticle properties as well as the detection of biomolecules including DNA, RNA, protein, enzyme, bacteria, virus, vesicles and others. This minireview summarizes recent advances in electroanalytical applications of SPIEC according to different analytical methods, i.e., direct electrolysis of nanoparticles or labeled nanoparticles, direct electrolysis of soft particles encapsulated redox molecule, indirect electrochemistry of particles, area and diffusion blocking, and changes in current magnitude and collision frequency.

Permanently Heated Micro-Wire Electrodes For Electrochemistry Above The Boiling Point, Zhihua Chang

Legacy Theses & Dissertations (2009 - 2024)

Heated micro-wire electrodes offer lots of advantages, such as, accurate temperature control, enhanced diffusion and accelerated reaction kinetics through micro-stirring effect, easy cleaning, and low cost, etc. Its application in high temperature electrochemistry has gained lots of interests since its debut in the mid-1990s. A maximum of 250 °C has been reported using heating pulses in duration of 5 ms. For various applications, permanently heating would be more useful. In this study, two types of micro-wire electrodes were successfully developed for electrochemistry above the boiling point with acetaminophen as model compound and a continuous heating time of at least 2 …

Electrochemical Detection Of Fentanyl Using Screen-Printed Carbon Electrodes With Confirmatory Analysis Of Fentanyl And Its Analogs In Oral Fluid Using Liquid Chromatography-Tandem Mass Spectrometry, Colby E. Ott

Graduate Theses, Dissertations, and Problem Reports (ETD)

Utilizing screen-printed carbon electrodes (SPCEs), a fast, simple, and sensitive approach toward the detection, identification, and quasi-quantitation of fentanyl was achieved both in an electrochemical cell and as a drop on the electrode surface. Electro-oxidation of fentanyl at the electrode was demonstrated using adsorptive stripping square-wave voltammetry between -0.5 V and +1.6 V with 100 mM Tris-HCl buffer at pH 8.5 as supporting electrolyte. Parameter optimization was conducted during method development to include supporting electrolyte and pH, electrochemical technique, pre-treatment and equilibration time, and various surface modifications. The simplest method utilizing an unmodified SPCE was determined to be appropriate for …

Electropolymerization Of Polyaniline In The Presence Of Ferricyanide: Electrochemical, Spectroscopic And Gravimetric Studies, Lucas Marinelli

Master's Theses

In this work, ferricyanide-doped polyaniline (PANI) is electropolymerized by constant current and cyclic voltammetry (CV) measurements with simultaneous monitoring of mass changes using electrochemical quartz crystal microbalance (eQCM). Raman spectroscopy, Fourier transform infrared spectroscopy and CV measurements confirm the incorporation of the ferricyanide into the film and indicate modified electrical conductivity. UV-Vis absorbance spectroscopy and Raman spectroscopy confirm the conducting ‘emeraldine-salt’ state and confirm the presence of polarons, i.e. charge carriers.

The addition of ferricyanide during electropolymerization of the PANI film results in an increase of polymerization rate as confirmed using eQCM. A decrease in counter ion ingress/egress and an …

High Resolution Imaging Of Single Nanoparticles And Two-Dimensional Nano-Material By Scanning Electrochemical Microscopy, Tong Sun

Dissertations, Theses, and Capstone Projects

Electrochemistry at nanostructured interfaces is of significant current interest. Metal nanoparticles (NPs) and two-dimensional semiconductor nanomaterial are particularly important because of their applications in catalysis, energy conversion and storage, sensors, and medicine. Electrocatalytic processes at such nanostructured interfaces are essential for the generation of hydrogen and other types of fuels and photochemical energy conversion. Nanoscale electrochemical experiments require the fabrication and characterization of nanometer-size electrochemical probes. The main advantages of the nanoprobes include very fast mass-transfer rate, high signal-to-noise ratio and extremely fine spatial resolution of electrochemical imaging. During my Ph.D. research, nanoscale disk-type platinum electrochemical probes were developed for …

Acetylcholinesterase Biosensor Platform Based On Bp2000 For The Detection Of Carbaryl, Ming-Han Zhang, Jun-Qiao Jiang, Jun-Jie Ge, Wei Xing

Journal of Electrochemistry

With the purpose of providing a new method for carbaryl (a pesticide) detection, on the basis of the principle that acetylcholinesterase (AChE) activity can be restrained by carbaryl, an AChE biosensor platform based on BP2000 (as a fixation) was constructed by dropping method. As a result, it revealed that AChE immobilized on BP2000 maintained its catalytic activity for acetylcholine (ATCl), and due to the introduction of the BP2000 material, the effective electrochemical surface area of the modified electrode was enlarged. In addition, the electrochemical oxidation at the modified electrode occurred at low potential (0.630 V) accompanied by proton transmission. The …

Comparing Laser Assisted Pulling And Chemical Vapor Deposition Methods In The Fabrication Of Carbon Ultramicro- And Nanoelectrodes, Theophilus Neequaye

Electronic Theses and Dissertations

Ultramicroelectrodes (UMEs) (limiting dimensions <~25 μm) and nanoelectrodes (<~100 nm) exhibit enhanced electrochemical properties compared to macroscopic electrodes. Their small sizes and enhanced properties make them well-suited for various interesting and important applications such as measuring redox-active species in nonaqueous solvents, studying intermediates of fast electrochemical reactions, and investigating electrochemical and electrocatalytic properties of single nanoparticles. While UMEs are commercially available, nanoelectrode fabrication is still largely confined to research labs. Various methods for constructing nanoelectrodes have been reported and continue to be developed, but most require considerable expertise, and comparisons between different fabrication processes are lacking. In this work, a comparison of laser-assisted pulling and chemical vapor deposition (CVD) methods of electrode fabrication is made with the aim of optimizing production of carbon nanoelectrodes for single nanoparticle electrochemical measurements. By examining effects of pulling parameters, post-pulling treatments, and CVD processing, electrodes as small as ~50 nm were successfully produced.

3d-Printed Fluidic Devices And Incorporated Graphite Electrodes For Electrochemical Immunoassay Of Biomarker Proteins, Abdulhameed Alabdulwaheed

Electronic Theses and Dissertations

Biomarkers are measurable indicators of health status or disease state that can be used for diagnosis and may help guide patient treatment strategies. Enzyme-linked immunosorbent assays (ELISA) and other many clinical techniques currently used for measuring biomarker proteins lack sensitivity, demand high analysis cost, are often not well-suited for measuring multiple biomarkers in a single sample, and require long analysis times. Here, we demonstrate simple, low-cost 3D-printed flow-through devices with integrated electrodes modified with gold nanoparticles (AuNPs) for electrochemical immunoassays of S100B, a biomarker protein related to conditions like skin cancer and brain injuries. Flow-through devices are fabricated from photocurable-resin …

Photoelectrochemical Studies On Non-Noble Metal Based Catalysts Towards Tandem Solar Water Splitting, Arun Siddarth Sridhar

Dissertations

Photoelectrochemical (PEC) water splitting makes direct use of solar energy incident on semiconductor photoelectrodes, and it is a convenient, economic option to produce high purity hydrogen at low temperatures. The use of multiple light absorbers can increase overall solar energy utilization and provide a solution to the trade-off between overall band gap and band edge positioning of photoelectrodes specific to solar water oxidation and water reduction. The study of non-noble metal based catalysts for hydrogen evolution reaction (HER) and oxygen evolution reactions (OER) are essential for economic practical commercialization of photo-electrolyzers. This dissertation focuses on the use of a variety …

Biosensing And Catalysis Applications Of Nanoporous Gold (Npg) And Platinum-Speckled Nanoporous Gold (Npg-Pt) Electrodes, Christopher J. Freeman

Theses and Dissertations

The importance of porous materials has risen substantially in the last few decades due to their ability to reduce the size and cost of bioanalytical devices and fuel cells. First, this work aims to describe the fabrication of nanoporous gold (NPG) electrodes that are resistant to electrode passivation due to fibrinogen biofouling in redox solutions. The effect on potentiometric and voltammetric experiments was seen as a deviation from ideal behavior on planar gold electrodes, whereas NPG electrodes were consistently behaving in a Nernstian fashion at low concentrations of ferri-ferrocyanide (£100 mM). An improvement in electrode behavior on NPG electrodes versus …

The Electrochemical Deposition Of Samarium And Europium Dissolved In Ionic Liquid Solvent, Bea Martinez

UNLV Theses, Dissertations, Professional Papers, and Capstones

Rare-earth elements include the lanthanide series in the periodic table with the addition of scandium and yttrium. China produces approximately 95% of the world’s rare-earths supply and is the largest consumer of the world’s rare earth supply. Domestic production of rare-earth metals is a priority in the US. The domestic demand for rare-earth elements is largely based on their use in electronic devices, catalytic converters, and more importantly defense applications. Therefore, China’s monopoly of rare-earth elements is viewed as a threat to national security. Although capital investments have resulted in an increase in domestic mining and refining of rare-earth materials, …

Electrochemical Time Of Flight For Rapid And Direct Measurement Of Diffusion Coefficients, Jonathan C. Moldenhauer

Graduate Theses and Dissertations

The determination of diffusion coefficients is of fundamental importance to the understanding of electrochemistry and sensors. Developing a method by which diffusion coefficients of Red/ox active analytes can be determined quickly and elegantly, would be a great advancement over presently accepted methods. This dissertation reports the reviving electrochemical time of flight (ETOF), and developing a method that allows for empirical determination of diffusion coefficients from a single measurement. ETOF is a generate and detect experiment where the time an electrochemically generated species takes to transit a known distance is measured and related to the diffusion coefficient of the species. The …

An Electrochemical Characterization Of A Vanadium-Based Deoxydehydration Catalyst, Joel Eric Baker

Graduate Theses and Dissertations

Alternative methods for the conversion of polyols into olefins, be it for carbon storage or hydrocarbon fuel production, have become prevalent in today’s chemical industry. One process in particular, deoxydehydration (DODH) has been proven effective in taking sustainable biomass derivatives and converting them through the utilization of various homogenous metal catalysts. While this process may show productive yields and material conversion, it is hindered by the need of a sacrificial reductant. This makes a novel process economically unviable and relatively unused outside of scientific research. That fact begs the question: Can the process be improved? It is proposed here that …

Adsorption Behavior Of Rhodamine 6g On Silver Surfaces Studied By Electrochemical Surface-Enhanced Raman Spectroscopy, Chan-Juan Chen, Cheng Zong, Guo-Kun Liu, Bin Ren

Journal of Electrochemistry

Rhodamine 6G (R6G) is one of the most common probe molecules employed in single molecule surface-enhanced Raman spectroscopy (SM-SERS). The study in adsorption behavior of R6G will help understand the interactions between R6G and surface. In this paper, we used electrochemical surface-enhanced Raman spectroscopy (SERS) to study the potential-dependent adsorption behavior of R6G on silver electrodes. Our results show that when the potential moved negatively, the orientation of R6G on silver surface changed from vertical to inclined adsorption. This result indicates that the abnormal SM-SERS spectra of R6G observed in the former SM-SERS studies from other research groups are due …

Fabrication Of Riboflavin Electrochemical Sensor Based On Au Nanoparticles/Polydopamine/Carbon Nanotubes Modified Glassy Carbon Electrode, Hua-Ping Peng, Mei-Ling Yu, Xin Liu, Pan Liu, Wei Chen, Ai-Lin Liu, Xin-Hua Lin

Journal of Electrochemistry

A novel electrochemical platform for the high sensitivity detection of riboflavin was constructed by Au nanoparticles/polydopamine/carbon nanotubes (Au-PDA-MWCNTs) nanocomposite modified glassy carbon electrode. The Au-PDA-MWCNTs nanocomposite was synthesized by in situ reduction method. The characteristics of the as-prepared Au-PDA-MWCNTs nanocomposite modified electrodes were investigated by using UV-Vis spectroscopy, scanning electron microscopy (SEM) and electrochemical methods. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to study the electrochemical behavior of riboflavin (RF) at Au-PDA-MWCNTs nanocomposite modified electrodes. The results demonstrated that the present electrochemical sensor exhibited a wide linear range from 5×10^-9 mol•L^-1to 1×10^-5 mol•L …

Development Of Single And Array Electro-Chemical Sensors For Real-Time Trace Metal Analysis In Aqueous Environmental Media, Yuanyuan Yang

Wayne State University Dissertations

Detection of trace metals has great importance in environmental and biological applications. While traditional electrochemical techniques have played critical roles in this field, their usefulness is limited by temporal resolution, Hg toxicity and stability concerns. Recently, we developed a method using fast-scan cyclic voltammetry (FSCV) at carbon-fiber microelectrodes (CFMs) to achieve rapid measurement of metal ions with high sensitivity, selectivity, and stability. Through optimizations this method showed strengths in real-time trace metal analysis. ‬‬‬‬‬‬

‪Analytical selectivity was improved via covalent functionalization on CFMs. We employed diazonium electrochemical reduction followed by click chemistry to create robust covalent attachments. We showcased its …

Building And Optimizing A Spectroelectrochemical System For The Study Of Shewanella Putrefaciens, Jonathan Muscolino

Master's Theses

Shewanellaceae are among the most widely studied electroactive microorganisms. This study reports on Shewanella putrefaciens under anaerobic conditions during applied potential while monitored by spectroscopy. The attachment of the microbe Shewanella putrefaciens onto an indium tin oxide electrode was found to occur after 2 hr of +0.2 V applied potential. Microbial detachment occurred with a 5 mV/s scan rate cyclic voltammogram from +0.2 V to -0.5 V to +0.2 V. This was confirmed through use of a spectroelectrochemical apparatus utilizing a standard 3 electrode setup with evanescent wave spectroscopy.

Fabrication And Application Of Cytochrome P450 Electrochemcial Biosensor In Drug Metabolism, Xuan Xu, Ju-Sheng Lu, Song-Qin Liu

Journal of Electrochemistry

The process of drug metabolism plays an important role in drug efficacy and toxicity in vivo. Thus, the development of cheap, continent, rapid and high-throughput method for drug metabolism studies has great guiding significance for the design of new drugs, the determination of drug dosage and the detection of clinical drugs. Since the key role played by Cytochrome P450 (CYP450) in phase-I drug reaction, the constructed CYP450 enzyme biosensor can be used for the initial screening of drugs. It is found that the replacement of coenzyme NADPH with an electrode is to provide two electrons demanded in the catalytic reaction. …

Plasma Treated Mesoporous Tio2 Thin Films For Energy Storage Applications, Allen D. Reed

Theses and Dissertations--Chemistry

Mesoporous TiO₂ films treated with N₂/argon plasma or H₂ plasma were studied for use in photoelectrochemical water splitting and electrochemical supercapacitors, respectively. Cubic-ordered mesoporous thin films were prepared by a templated sol-gel method. UV-Vis absorbance spectra indicated that nitrogen plasma treatment significantly reduced the band gap of the TiO₂. XPS analysis showed that nitrogen atoms are incorporated into substitutional sites, rather than interstitial. Photocatalytic activity of nitrogen-doped TiO₂ films was evaluated by chronoamperometry and linear sweep voltammetry. Compared to pristine TiO₂, plasma-treated films showed remarkable photocurrent enhancement (up to 240 times) …

Enzyme-Based Dna Electrochemical Biosensors: Recent Trends, Chun-Shui Lin, Yi-Ru Wang, Xi Chen

Journal of Electrochemistry

DNA electrochemical sensors have greatly promoted the development of biosensors for their high sensitivity, good selectivity, short analysis time and low cost. To further improve the detection sensitivity and selectivity, protein enzymes, functional nucleic acid enzymes etc. are often used due to the advantages of high catalytic efficiency and specificity. This review demonstrates the research progress of electrochemical sensors based on enzymatic amplification and analyses some existing problems of electrochemical sensors.

Electrochemical And Surface Enhanced Raman Spectroscopic Studies Of Benzimidazole On Nickel Electrode, Ping-Jie Wei, Ya-Xian Yuan, Min-Min Xu, Jian-Lin Yao, Ren-Ao Gu

Journal of Electrochemistry

By measuring cyclic voltammograms and polarization curves, the inhibition effects of benzimidazole (BMIH) concentration in acetonitrile system on a nickel electrode were investigated. It was found that the oxidation and the corrosion potentials shifted positively, and the oxidation current decreased with the increase in the concentration of BIMH. Potential dependent adsorption and film formation behavior of BMIH on the nickel electrode were investigated by in situ SERS spectroscopy. With the potential moving from negative direction to positive direction, the complexes made of BIMH and nickel were formed, preventing the nickel electrode from corrosion. In addition, the 0.001 mol·L^-1 of …

Modified-Electrodes For Redox-Magnetohydrodynamic (Mhd) Pumping For Microfluidic Applications, Christena Kayl Nash

Graduate Theses and Dissertations

A new microfluidic pumping and stirring technique was demonstrated for lab-on-a-chip applications. Microfluidics was accomplished via redox-MHD, which takes advantage of a body force (F_B) that is generated when there is a net movement of ions in solution (j) in the presence of a perpendicular magnetic field (B), according to the equation F_B = j×B. In this work the movement of ions in solution was generated using electrodes modified with the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) rather than a redox species in solution, which can interfere with analyte detection and with biological species. …

Investigation And Characterization Of Pt-Modified Au Catalysts And Polymer Composites By Electrochemistry, Raman And Surface Enhanced Raman Spectroscopy (Sers), Ranjani Muralidharan

USF Tampa Graduate Theses and Dissertations

This dissertation thesis consists of six chapters. The main focus of this study is the need for understanding the reaction mechanism and intermediates formed on Pt-modified Au surface as anode catalysts in the formic acid fuel cells. Chapter 1 gives an introduction to formic acid and methanol fuel cells, an overview of the current catalysts employed at the anode of the fuel cells, specifically the Pt-modified Au electrodes as potential catalysts and the different deposition methods for preparing this catalytic surface. Information about different electrochemical methods used like cyclic voltammetry and potential step method along with other characterization methods and …

Fabrication And Characterization Of High Surface Area Gold Electrodes, Madhura S. Damle

Theses and Dissertations

High surface area gold electrodes are very good substrates for biosensors, catalysis and drug delivery. Their performance is characterized by good sensitivity, low detection limit and high signal. As a result, extensive research is being carried out in this field using different approaches of fabrication to generate high surface area porous electrodes of different morphology, pore size and structure. The morphology of the electrodes can be changed based on whether the approach involves a template or not, types of metal deposition, method and time of dealloying etc. The deposition of metal can be carried out using various approaches such as …

Microfluidics Guided By Redox-Magnetohydrodynamics (Mhd) For Lab-On-A-Chip Applications, Vishal Sahore

Graduate Theses and Dissertations

Unique microfluidic control actuated by simply turning off and on microfabricated electrodes in a small-volume system was investigated for lab-on-a-chip applications. This was accomplished using a relatively new pumping technique of redox-magnetohydrodynamics (MHD), which as shown in this dissertation generated the important microfluidic features of flat flow profile and fluid circulation. MHD is driven by the body force, FB = j × B, which is the magnetic part of the Lorentz force equation, and its direction is given by the right hand rule. The ionic current density, j, was generated in an equimolar solution of potassium ferri/ferro cyanide by applying …

Combination And Applications Of Time-Resolved Surface Plasmon Resonance Spectroscopy And Electrochemical Methods, Yu Bao, Yan Mao, Wei Wang, Zheng-Gang Li, Li Niu

Journal of Electrochemistry

Electrochemical-surface plasmon resonance (EC-SPR) technique, developed in recent years, is a new technology which combines time-resolved surface plasmon resonance spectroscopy and electrochemical methods. Surface plasmon resonance (SPR) is a physical phenomenon generated by optical coupling using a metallic thin film and is very sensitive to optical analysis. The principles of SPR and EC-SPR are briefly introduced and the applications of the combination of SPR spectroscopy with electrochemical techniques are reviewed in this paper. This new technology has been widely used in such research areas as reaction dynamics, biochemical sensors, electrode/electrolyte interfaces, kinetic parameters and bimolecular interactions.

Electrochemical Behavior Of Imidacloprid, Jie-Qiong Wang, Wang Zhang, Ming Chen, Guo-Wang Diao

Journal of Electrochemistry

The electrochemical behavior of imidacloprid（IDP）on glassy carbon electrode has been investigated by cyclic voltammetry. The result shows that the electrochemical reduction of IDP is irreversible and controlled by diffusion. At 25 ℃, the numbers of the electrons transferred of IDP in the electrochemical reaction are four. The diffusion coefficient of IDP is 2.44×10⁶ cm²·s^-1 and the diffusion activation energy is calculated to be 9.33 kJ·mol^-1.

Studies Toward The Development Of A Microelectrode Array For Detection Of Dopamine Through Redox Cycling, Anupama Aggarwal

Graduate Theses and Dissertations

Redox cycling is an electrochemical technique that cycles the reversible redox species between its oxidative states repeatedly on generator and collector electrodes. Two or more individually-addressable microelectrodes located close to each other allow redox cycling to be possible. Electrochemical behavior of a biologically important molecule, dopamine is examined under redox cycling conditions. To our knowledge, this is the first report on detection of physiological concentration of dopamine in presence of up to 100 times excess ascorbate with the use of redox cycling, without the involvement of polymer coating such as Nafion®.

Microfabrication was used to produce different geometries (parallel bands …

Synthesis, Extraction, Dissolution, And Voltammetry Of F-Species In A Room Temperature Ionic Liquid Solvent, Wendy Jacqueline Pemberton

UNLV Theses, Dissertations, Professional Papers, and Capstones

Room temperature ionic liquids (RTILs) are salts that are liquids from as low as -96 °C to up to 100 °C. RTILs are of high interest in many fields of study because of their negligible vapor pressure, high electrochemical stability, high conductivity, and wide electrochemical windows. These diverse solvents have recently been used in organic synthesis, as extraction solvents, and as electrochemical solvents. It is as a direct result of the multifunctional capabilities of these RTIL solvents that they are examined in this work. The ability to probe the chemistry of lanthanides and actinides is based on the unique properties …

In-Situ Surface Enhanced Raman Scattering Electrochemical Investigation Of 4-Aminoantipyrine On Silver Electrode, Li-Jun Zhang, Wei Song, Ling Chen, Zong-Rang Zhang, Hai-Feng Yang

Journal of Electrochemistry

In this paper, 4-AAP was self-assembled on silver surface to form monolayers. Surface-enhanced Raman Spectroscopy (SERS) was used to in-situ investigate the adsorption mechanism of the 4-aminoantipyrine(4-AAP) on silver surface dependent on shifting potentials and the effect of solution pH. Based on density functional theory(DFT) calculation of vibration modes,approximate assignment of 4-AAP SERS spectrum was conducted. In situ SERS spectral electrochemical experiments indicated that the 4-AAP monolayers experience a dynamic adsorption process from a tilted fashion to a more vertical mode for benzene ring and more parallel for pyrine ring with the potential applied toward more negative voltages. The complete …