Chemistry Commons^™

Electrochemical Detection For The Corrosion Of Reinforcing Steel In Concrete During Immersion And Drying Cycles, Bing-Li Jia, Fa-He Cao, An-Na Chen, Jian-Qing Zhang

Journal of Electrochemistry

The corrosion behavior of reinforcing steel in concrete under dry-wet cycle condition has been studied by electrochemical noise(EN) compared with the electrochemical impedance spectroscopy(EIS),SEM micrographs and EDS.The statistical method has been employed to analyze the EN data of reinforcing steel in concrete,which revealed three different corrosion stages of reinforcing steel in concrete,including the dissolution of the passive film,the active corrosion and the cumulation of corrosion product.The wavelet transform has also been employed,which indicated that steel in concrete with pH 1 is associated with uniform corrosion,while steel in concrete with pH 3 and pH 7 are associated with localized corrosion,such as …

Preparation And Characterization Of The Silane-Phosphonic Acid Composite Passivation Coating For Electrogalvanized Steel, Yong Guan, Jian-Guo Liu, Chuan-Wei Yan

Journal of Electrochemistry

A new silane-phosphonic acid composite passivation coating process has been developed for the protection of electrogalvanized steel based on N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane(AAPTMS),γ-(2,3-epoxypropoxy)propyltrimethoxy-silane(GPTMS) and 1-hydroxy ethylidene-1,1-diphosphonic acid(HEDP).The results of X-ray photoelectron spectroscopy(XPS),Fourier transform infrared spectroscopy(FTIR),potentiodynamic polarization scan,electrochemical impedance spectroscopy(EIS) and neutral salt spray(NSS) tests indicated that the major structure of the prepared silane-phosphonic acid composite passivation coating consisted mainly of Si—O—Si and Si—O—P bonds.The area of white rust was not more than 5% of the total panal after 120 h NSS test,which could be compared favourably with the chromate colour passivation coating.However,the corrosion reaction on the anode of the silane-phosphonic acid composite passivation …

Electrochemical Behaviors Of Organic Coating/Matal Substrate Under Simulated Deep Sea Environment Partⅰ.Effects Of Seawater Pressure On Transportation Behavior Of Water Through Coating And Coating′S Protective Performance, Bin Liu, Zhi-Gang Fang, Tao Wang, Hong-Bin Wang

Journal of Electrochemistry

By means of electrochemical impedance spectroscopy(EIS),the electrochemical behaviors of organic coating/metal substrate were studied under simulated deep sea environment in the laboratory.Effects of seawater pressure on the transportation behavior of water through coating and the protective performance of coating were analyzed.The experimental results showed that,compared to normal pressured seawater,there were different impedance characteristics of coating in 3.5 MPa pressured seawater.The main observations were that high seawater pressure accelerated the process of water uptake and invalidation of coating,increased water absorption,and lowered the anti-corrosion property of coating.

Initial Stage Of Atmospheric Corrosion Of Ndfeb(M35) In A Simulated Marine Atmosphere, Chun-Ling Li, Yuan-Tai Ma, Ying Li, Fu-Hui Wang

Journal of Electrochemistry

This study detailed the atmospheric corrosion behaviour of sintered NdFeB(M35) in a simulated marine atmosphere with 80% relative humidity(RH).The dissolution and subsequent reaction of NaCl particles cause the attack of NdFeB.The corrosion presented three representative types:if the electrolyte covered magnetic phase and Nd-rich phase,the Nd-rich phase was corroded firstly due to galvanic effect;if the electrolyte covered magnetic phase,magnetic phase was corroded along the grain boundary;if the electrolyte located near the position of defects,corrosion progressed along with the defect because of low concentration of oxygen inside the defect.With corrosion progressing,local corrosion areas were mutually connected,with Nd-rich phase and grain boundary being …

Photoelectrochemical Properties Of N, S, And Cl Modified Nano Tio2 Thin Films, Hong Yun, Chang-Jian Lin, Jing Li, Rong-Gui Du

Journal of Electrochemistry

The nitrogen(N),sulfur(S) and chlorine(Cl) modified nano TiO₂ thin films were prepared by adding Ti(O-n-Bu)₄ as the precursor into concentrated HNO₃,H₂SO₄ and HCl Solutions,respectively,on different substrates in a sol-gel process.The photoelectrochemical performances of N,S and Cl modified nano TiO₂ thin films have been studied by UV-vis(DRS),photocurrent curves,EIS and OCP-time curves.N-modified TiO₂ nano films show better surface structure,which helps to improve the quantum efficiency of nano TiO₂ thin films.

Hydrothermal Reduction Synthesis Of Lifepo4 And Its Electrochemical Performance, Hong-Li Zou, Guang-Hui Zhang, Pei-Kang Shen

Journal of Electrochemistry

The cathode materials of LiFePO₄ were prepared via a hydrothermal reduction method using FeCl₃ as Fe source and iron as a reducing agent.The results showed that ferric salt could be reduced to ferrous salt completely under the hydrothermal condition and pure-phase LiFePO₄ was obtained based on the test results of XRD and FTIR.Carbon-coated LiFePO₄ was synthesized by pyrolysisng glucose at high temperature.The morphologies of pure LiFePO₄ displayed cluster-like while the LiFePO₄/C displayed sphere-like particles.The electrochemical test showed that the LiFePO₄/C had good rate performance,while LiFePO₄ delivered much lower discharge capacity.

Effects Of Solvents And Electrolyte Salts On The Electrochemical Reduction Of Oxygen In Non-Aqueous Electrolytes, Yan-Yan Tian, Wei Wu, Jun Gao, Yong Yang

Journal of Electrochemistry

The electrochemical reduction processes of oxygen in different non-aqueous solvents such as acetonitrile(MeCN),propylene carbonate(PC) and their mixtures were investigated by cyclic voltammetry method.The results indicated a one electron reduction of oxygen to O^2-occured in these systems as a first step reduction,no matter whether in tetrabutylammonium hexafluorophosphate(TBAPF₆)/MeCN or TBAPF₆/PC electrolyte.However,the CV curves in 0.1 mol·L^-1 TBAPF₆/MeCN showed a couple of reversible redox peaks,indicating that the reduction process of oxygen was irreversible in the 0.1 mol·L^-1 TBAPF₆/PC electrolyte.In the PC-based electrolyte,the reduction current peak reduced largely and the oxidation peak …

Corrosion Electrochemical Behavior Of Am60 Magnesium Alloys In Automobile Engine Coolants, Ling-Jie Li, Sha Wang, Yin Xiao, Jun Lan, Jing-Lei Lei, Sheng-Tao Zhang, Fu-Sheng Pan

Journal of Electrochemistry

The polarization measurements and electrochemical impedance spectroscopy(EIS) were used to study the corrosion electrochemical behavior of AM60 magnesium alloys in three kinds of commercial coolants for automobile engine.Results show that the tested commercial coolants are slightly corrosive to AM60 magnesium alloys and their corrosivity varies from coolant to coolant.The coolant C is the least corrosive among the studied commercial coolants and the coolant A is more corrosive than the coolant B and C.The coolant C appears to be the most promising coolant for automobile engine made by magnesium alloys.The coolant resistivity plays an important role in the corrosion of AM60 …

Study Of The 11-Ferrocenylalkanethiol Redox-Induced Structure Changes By Flow-Injection Electrochemical Surface Plasmon Resonance, Xiu-Juan Xiao, Yong-Hui He, Juan Xiang, Bin Ren

Journal of Electrochemistry

Redox-induced orientation changes of self-assembled monolayers(SAMs) of 11-ferrocenylundecanethiol(FcC₁₁SH) were studied by the flow-injection electrochemical surface plasmon resonance(FI-EC-SPR).Results indicated that there existed two mechanisms concerning the redox-induced structure change of the self-assembled monolayer of ferrocenylalkanethiols:the electrostatic repulsion between the positively charged surface and the ferricenium cation and that among the cations led to a decrease in the tilt angle of the alkanethiol chain;upon Fc oxidation,the Fc group rotated from a tilted conformation to a position where the cyclpentyldiene plane became perpendicular to the electrode.

Electrodeposition Of Lead Dioxide From Dluoroborate Solutions, Chun-Mei Kong, Yong-Ming Tang, Wen-Zhong Yang, Xiao-Yuan Yang

Journal of Electrochemistry

The PbO₂ anodes were prepared on platinum from fluoroborate media and its doped solutions by electrodeposition technique.Elecchemical and pysicochemical properties of these PbO₂ films were studied by cyclic voltammetry methods,XRD and SEM.The results showed that the presence of BF₄-increased PbO₂ electrodeposition rate;the prepared lead dioxide consisted of β-PbO₂;the preferential orientation of crystals and surface morphology were affected a lot by doping F-and Fe³⁺.The FB/F-Fe-PbO₂ electrode exhibited regular-shaped layers with compact morphology.Furthermore,increasing current density also change the preferential orientation of PbO₂ crystals.

Research On Nafion/Sio2 Composite Membrane In All Vanadium Redox Flow Battery, Dong-Dong Liu, Mao-Cai Lin, Tao Guan, Qing-Chun Yu

Journal of Electrochemistry

The Nafion117/SiO₂ composite membrane was prepared by sol-gel method.The results showed that,during composite membrane preparation process,the ratio of MeOH and TEOS did not affect the penetration rate of VO²⁺ basically,however,the lowest permeability of 427×10-9cm²/s in the membrane was achieved while hydrolysis time was 10 min and natural drying for 24 h after hydrolysis,which reduced by 52 times than that in Nafion117 membrane.The SEM tests proved that SiO₂ grains grew bigger in the composite membrane during the natural drying,and most of the holes in Nafion117 were filled.Single cell test showed the battery power efficiency was improved …

Electrochemical Performance Of Zinc Tetra (Trifluoroethoxy) Phthalocyaninate In Aqueous And Nonaqueous Solvents, Xiao-Shan Wu, Li-Ying Huang, Jin-Que Zhang, Shan-Lan Zhu

Journal of Electrochemistry

The cyclic voltammetric performance of ZnPcF in N,N-dimethylformaide(DMF),dimethyl sulfoxide(DMSO) solution and phosphate buffer solutions(PBS) has been examined.The results showed that four pairs of redox peaks appeared in nonaqueous solvents,and the values of half-wave redox potential were 0.558 V,-0.761 V,-1.034 V,-1.417 V,respectively,exhibiting four quasi-reversible phthalocyanine ligand based one-electron transfers.In PBS only two redox peaks were observed and the values of half-wave redox potential were-0.885 V,-1.104 V,exhibiting irreversible behavior characteristics.Comparing to the zinc phthalocyanine(unsubstitute ZnPc),introducing electron-withdrawing groups-trifluoroethoxyl to the peripheral sites of the phthalocyanines shifts the redox processes of the complex toward positive potentials.

Study On Preparing Technology And Corrosion Resistance Of Ti/Zr Based Chromium-Free Chemical Conversion Coating On Zinc Electroplating Layer, Yong Guan, Jian-Guo Liu, Chuan-Wei Yan

Journal of Electrochemistry

In this paper,we obtained environmental-friendly chromium-free chemical conversion coating on the non-cyanide alkaline zinc electroplating layer by employing the optimized Ti/Zr based conversion technique.At the same time,the performances of the Ti/Zr based conversion coating were compared with chromate colour passivation coating.The corrosion resistances of the conversion coatings were investigated by using neutral salt spray(NSS) test,potentiodynamic polarization and electrochemical impedance spectroscopy(EIS).The results showed that the white rust appeared after 96 hours when the NSS test was performed on the Ti/Zr based conversion coating,which was close to the corrosion resistance rating of chromate colour passivation coating.Compared with the chromate passivation coating,the Ti/Zr …

The Roles Of The Width Of Gas/Liquid/Solid Three-Phase Boundary Zone Of Dispersion Water Films In Atmospheric Corrosion Of Metals, Jia Wang, Jing Jiang

Journal of Electrochemistry

The roles of TPB(Three-Phase Boundary) width in the corrosion processes of metals under dispersed water films were investigated by electrochemical techniques combined with contact angle measurement.It is found that both cathodic limiting current density and corrosion current density linearly increases with increasing the TPB width,confirming the important role of TPB width in gas/liquid/solid multiphase corrosion systems.Based on above results,the effect of water film thickness on atmospheric corrosion rate was quantitatively evaluated by the TPB width.

Comparative Studies On The Deterioration Process Of Organic Coatings Under Immersed And Cyclic Wet-Dry Conditions By Eis, Yu-Nan Li, Jia Wang, Wei Zhang

Journal of Electrochemistry

Under the immersed and wet-dry cyclic conditions,the deterioration processes of the organic coatings on carbon steel surface have been comparatively studied by using electrochemical techniques.The wet-dry cycles were carried out in the alternating conditions of 12 h by immersing in a 3.5% sodium chloride solution and drying at 25 ℃ and 50% RH.Coating resistance,Rf,coating capacitance,Cf,and double layer capacitance,Cd,were monitored continuously and separately under above two conditions.The percentages of the intenfacial active area,Aw,were estimated from the obtained double layer capacitance,Cd.According to the EIS characteristics,the entire deterioration processes under above two mentioned conditions can be divided into three main stages,consisting of the …

Electroless Deposition And Characterization Of Nickel Coating In Lead-And Cadmium-Free Bath, Fang-Zu Yang, Ming-Hui Chen, Xia-Jing Huang, Zhong-Qun Tian, Shao-Min Zhou

Journal of Electrochemistry

Technology of electroless nickel deposition in lead-and cadmium-free bath was developed.Coating′s morphology,composition,structure and electrochemical activity were characterized by SEM,EDS,XRD and electrochemical methods.The results showed that,the deposition rate of nickel in self-catalysing was 22.4 μm·h^-1,which was increased by the increase of bath temperature and pH value.The effect of sodium hypophosphite on deposition rate was much more remarkable compared with nickel sulfate.The obtained nickel coating was 7.8% in phosphor weight content,having compact and neat surface morphology,amorphous structure,and good electrochemical corrosion resistance in sodium chloride solution.

Study On Aluminum Foils For Aluminum Electrolytic Capacitor, Hui-Zhong Tan, Guo-Qing Qian, Wen-Bao Wang, Lan Sun, Chang-Jian Lin

Journal of Electrochemistry

Scanning electron microscopy(SEM),X-ray diffraction(XRD),weight-loss method and electrochemical testing method were employed to study the chemical compositions and corrosion behaviors of hard foil and soft foil.The results showed that the surface morphology,chemical composition and crystal structure of hard foil and soft foil are different.It is found from electrochemical tests that the soft foil is suitable to the corrosion under low acidity conditions,which provides the base for developing the corrosion techniques under low acidity conditions.

The Sol-Gel Synthesis And Electrochemical Performance Of Li3V2(Po4)3/C Cathode Material For Lithium Ion Battery, Li-Ying Liu, Lian Chen, Hai-Yan Zhang, Yu-Chun Zhai

Journal of Electrochemistry

Li₃V₂(PO₄)₃/C was synthesized by sol-gel method with citric acid as chelate and C sources. Physical and electrochemical performances of as-prepared materials were characterized through XRD, SEM and galvanostatic charge-discharge tests,etc. The results showed that products produced by calcining at 800 ℃ for 12 h had a single phase crystal structure and relatively small particle sizes with uniform distribution. At 0.1 C, 0.5 C and 1 C, the initial specific discharge capacities were 153.0, 143.1 and 130.6 mAh·g^-1, respectively, and capacity efficiencies were 93.1%, 85.4% and 77.3% after 50 cycles, respectively. …

Eis Study On The Change Of Resistance And Water Absorption During The Failure Graduation Of Inorganic Zinc-Rich/Epoxy/Aliphatic Polyurethane Composite Coatings, Shao-Ping He, Jin-Ping Xiong, Yu-Ming Tang, Yu Zuo

Journal of Electrochemistry

The failure process of inorganic zinc-rich/micaceous iron oxide epoxy/aliphatic polyurethane composite coatings in 3.5% NaCl solution under ultraviolet radiation(UV) was studied with Electrochemical Impedance Spectroscopy(EIS).The result shows that the protective property of the coating was enhanced with the increase of total coating thickness,but the degree of improvement reduced gradully as the coating thickness increased.The shielding effect of the micaceous iron oxide epoxy was mainly reflected in the initial period of the service process,while in later period the coating performance largely depended on the zinc-rich primer.The change of the water uptake in the composite coating presented a 'three-stage' characteristic.The thinner the …

Systematic Approach To Electrostatically Induced 2d Crystallization Of Nanoparticles At Liquid Interfaces, Sumit Kewalramani, Suntao Wang, Yuan Lin, Huong Giang Nguyen, Qian Wang, Masafumi Fukuto, Lin Yang

Faculty Publications

We report an experimental demonstration of a strategy for inducing two-dimensional (2D)crystallization of charged nanoparticles on oppositely charged fluid interfaces. This strategy aims to maximize the interfacial adsorption of nanoparticles, and hence their lateral packing density, by utilizing a combination of weakly charged particles and a high surface charge density on the planar interface. In order to test this approach, we investigated the assembly of cowpea mosaic virus (CPMV) on positively charged lipid monolayers at the aqueous solution surface, by means of in situX-ray scattering measurements at the liquid–vapor interface. Theassembly was studied as a function of the solution …

The Distribution Of Dna Translocation Times In Solid-State Nanopores, Jiali Li, David Talaga

Department of Chemistry and Biochemistry Faculty Scholarship and Creative Works

This paper systematically investigates the effects of solution viscosity, applied voltage and DNA chain length on the distribution of DNA translocation times through 8 ± 2 nm diameter silicon nitride nanopores. Linear dsDNA translocation events were selected based on the magnitude of current blockage and accumulated into scatter plots of current blockage and event duration (translocation time). The translocation time distribution was fitted to the solution of a Smoluchowski-type equation for 1D biased diffusion to a sink. The DNA drifting speed under bias and diffusion constant were extracted from the fits as functions of solution viscosity, applied voltage and DNA …

Work Towards The Isolation And Characterization Of The Muscle Isoform Of Glucose 1,6-Bisphosphatase, Caleb J. Hiller

Theses and Dissertations

Glucose 1,6-bisphosphate is an important small molecule involved in the regulation of glycolysis. Four enzymes synthesize this compound. One enzyme is known to degrade it, glucose 1,6-bisphosphatase. Other groups have produced work that indicates that there are two isoforms of this enzyme, one predominant in the brain and one in the muscle. This thesis contains the work performed in attempts to isolate and characterize the muscle isoform of glucose 1,6-bisphosphatase. While this enzyme was not isolated, much was learned about it and the results from this work may help in the future identification of this enzyme.

Vibrationally Promoted Electron Emission At A Metal Surface: Electron Kinetic Energy Distributions, Jerry L. Larue, Tim Schäfer, Daniel Matsiev, Luis Velarde, N. Hendrick Nahler, Daniel J. Auerbach, Alec M. Wodtke

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

We report the first direct measurement of the kinetic energy of exoelectrons produced by collisions of vibrationally excited molecules with a low work function metal surface exhibiting electron excitations of 64% (most probable) and 95% (maximum) of the initial vibrational energy. This remarkable efficiency for vibrational-to-electronic energy transfer is in good agreement with previous results suggesting the coupling of multiple vibrational quanta to a single electron.

[Fe-Fe]-Hydrogenase Reactivated By Residue Mutations As Bridging Carbonyl Rearranges: A Qm/Mm Study, Stefan Motiu, Valentin Gogonea

Chemistry Faculty Publications

In this work, we found aqueous enzyme phase reaction pathways for the reactivation of the exogenously inhibited [Fe-Fe]-hydrogenases by O2, or OH−, which metabolizes to H2O (Dogaru et al., Int J Quantum Chem 2008, 108; Motiu et al., Int J Quantum Chem 2007, 107, 1248). We used the hybrid quantum mechanics/molecular mechanics (QM/MM) method to study the reactivation pathways of the exogenously inhibited enzyme matrix. The ONIOM calculations performed on the enzyme agree with experimental results (Liu et al., J Am Chem Soc 2002, 124, 5175), that is, wild-type [Fe-Fe]-hydrogenase H-cluster is inhibited by oxygen metabolites. An enzyme spherical region …

Design, Synthesis & Biological Activity Of Novel Protein Tyrosine Phosphatase (Ptp) Mimetics, Sridhar Reddy Kaulagari

USF Tampa Graduate Theses and Dissertations

Protein phosphorylation is a post translational modification of proteins in which a serine, a threonine or a tyrosine residue is phosphorylated by an enzyme, kinase. Phosphorylation of proteins is a reversible and very important regulatory mechanism that occurs in both prokaryotes and eukaryotes. Phosphorylation turns many protein enzymes on and off, preventing or causing many diseases such as diabetes, cancer and rheumatoid arthritis. The phosphorylation on tyrosine residues of proteins is essential for transmission of signals for cell growth, proliferation and differentiation. Protein tyrosine phosphatases (PTPs) in concert with protein tyrosine kinases (PTKs) regulate many signal transduction pathways by controlling …

A Highly Efficient Bismuth Salts-Catalyzed Route For The Synthesis Of Alpha-Aminophosphonates, Antara Banik, Sahil Batta, Debasish Bandyopadhyay, Bimal K. Banik

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

A convenient synthesis of different types of α-amino phosphonates via one-pot solvent-free three component reactions of aldehydes, amines and phosphites catalyzed by bismuth salts has been investigated. Bismuth triflate is found to be the most effective catalyst for this reaction.

Interaction-Dependent Pcr: Identification Of Ligand-Target Pairs From Libraries Of Ligands And Libraries Of Targets In A Single Solution-Phase Experiment, Lynn M. Mcgregor, David J. Gorin, Christoph E. Dumelin, David R. Liu

Chemistry: Faculty Publications

Interaction-dependent PCR (IDPCR) is a solution-phase method to identify binding partners from combined libraries of small-molecule ligands and targets in a single experiment. Binding between DNA-linked targets and DNA-linked ligands induces formation of an extendable duplex. Extension links codes that identify the ligand and target into one selectively amplifiable DNA molecule. In a model selection, IDPCR resulted in the enrichment of DNA encoding all five known protein-ligand pairs out of 67 599 possible sequences.

The Molecular Transport And Intercalation Of Guest Molecules Into Hydrogen–Bonded Metal-Organic Frameworks (Hmofs), Greg Anthony Hogan

Dissertations

The process of molecular transport and intercalation has been widely studied for many years, resulting in the discovery of molecular frameworks that are capable of hosting guest molecules or ions. Layered and porous metal-organic frameworks (MOFs) have been found to have applications in the field of catalysis, storage, separations, and ion-exchange. While MOFs are perhaps stronger materials, HMOFs have the advantage of being easily modifiable and more flexible. Because HMOFs have not been extensively studied for their ability to host molecules, and because their ability to withstand guest loss and guest exchange is essentially unknown, here we report the synthesis …

Dockomatic - Automated Ligand Creation And Docking, Casey W. Bullock, Reed B. Jacob, Owen M. Mcdougal, Greg Hampikian, Tim Andersen

Chemistry and Biochemistry Faculty Publications and Presentations

Background: The application of computational modeling to rationally design drugs and characterize macro biomolecular receptors has proven increasingly useful due to the accessibility of computing clusters and clouds. AutoDock is a well-known and powerful software program used to model ligand to receptor binding interactions. In its current version, AutoDock requires significant amounts of user time to setup and run jobs, and collect results. This paper presents DockoMatic, a user friendly Graphical User Interface (GUI) application that eases and automates the creation and management of AutoDock jobs for high throughput screening of ligand to receptor interactions.

Results: DockoMatic allows the user …

Importance Of Electronic Relaxation For Inter-Coulombic Decay In Aqueous Systems, Craig P. Schwartz, Shervin Fatehi, Richard J. Saykally, David Prendergast

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Inspired by recent photoelectron spectroscopy experiments on hydroxide solutions, we have examined the conditions necessary for enhanced (and, in the case of solutions, detectable) inter-Coulombic decay (ICD)—Auger emission from an atomic site other than that originally excited. We present general guidelines, based on energetic and spatial overlap of molecular orbitals, for this enhancement of inter-Coulombic decay-based energy transfer in solutions. These guidelines indicate that this decay process should be exhibited by broad classes of biomolecules and suggest a design criterion for targeted radiooncology protocols. Our findings show that photoelectron spectroscopy cannot resolve the current hydroxide coordination controversy.