Chemistry Commons^™

Identifying Conditions To Optimize Lactic Acid Production From Food Waste, Raymond M. Redcorn

Open Access Theses

There is an increased demand for lactic acid for the production of biopolymers and to aid nutrient removal in wastewater treatment. Food waste offers a source of soluble sugars to produce lactic acid, which does not increase land demand, but digestion conditions have yet to be optimized when co-digested with primary sludge. Food waste was collected from cafeteria waste bins, homogenized and seeded with primary sludge. A Box Behnken Response surface design was used to optimize lactic acid production based on pH, temperature, loading rate, and retention time. Subsequent experiments verified and refined those conditions to optimize for both yield …

Impact Of Nanostructure On Polymer-Based Nonvolatile Memory Devices, Seung Hyun Sung

Open Access Theses

Memory functionality is essential for many high-end electronic applications (e.g. , smart phones, personal computers). Particularly, organic nonvolatile memory devices based on polymer ferroelectric materials are a promising approach toward the development of low-cost memory due to the ease of processing and flexibility associated with the device. Here, we will focus on a memory device with a two-component active layer and a diode structure. This ferroelectric diode (FeD) has a nanostructured active layer, composed of ferroelectric and semiconducting polymers, and it can provide easy access to high-performance polymer-based memory devices. In order to create these nanostructured active layers, we …

Study Of Polyaniline For Use In An Organic Field Effect Transistor, Thomas Martin Sprinkle

Chemistry & Biochemistry Theses & Dissertations

Polyaniline's emeraldine base form was synthesized via chemical polymerization in HCl acidic media utilizing ammonium persulfate as the oxidant. Synthesis was done at room temperature and -30 'C and characterized for differences by X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry. Methanol soxhlet extraction was done to increase number average molecular weight from 77,400 to 81,000 and decrease the poly dispersity index from 3.82 to 2.14. Films were cast using N, N'- Dimethylpropyleneurea and N-Methylpyrrolidone and showed poor mechanical properties upon acidic doping.

Cyclic voltammetry was done with HC1 as the acidic media and an ITO coated slide as the …

Electrochemical Catalysis: A Dft Study, Li Li, Zi-Dong Wei

Journal of Electrochemistry

In this review, we focus on achievements in electro-catalysis based on the density function theory study. The relationships among the electrode potential, electronic structure of catalysts and electro-catalytic activity are summarized in three parts: the adsorption and desorption of species, electron transfer, and stability of catalysts. The electrode potential and the electronic structure (d-band center or Fermi (HOMO) energy) of catalysts significantly influence the formation, adsorption and desorption of surface species on electrode. The electro-catalytic activity can be improved by modulating the electrode potential and electronic structure of catalysts.

Electrocatalytic Oxidation Of Formate On Pd-Cu/C - Effect Of Dealloying Pretreatment, Kun Jiang, Ye Wang, Tao Lin, Wen-Bin Cai

Journal of Electrochemistry

Carbon supported highly dispersed Pd-Cu nanoalloy catalyst toward formate electrooxidation is prepared via one-pot synthesis by using ethylene glycol as the reducing agent and sodium citrate as the stabilizer. The as-prepared catalyst is structurally characterized by TEM and XRD. The Cu dealloyment is carried out through repetitive potential cycling of the Pd-Cu/C catalyst in an acidic solution. The dealloying effect on the performance of the Pd-Cu/C is investigated by using cyclic voltammetry and chronoamperometry, and the surface structural change of Pd-Cu/C is probed by in situ ATR-IR measurement. The results show that the as-prepared Pd-Cu/C processes a better long-term stability …

Synthesis Of Silver Nanoparticles Supported On Graphene Quantum Dots For Oxygen Reduction Reaction, Jian Ju, Wei Chen

Journal of Electrochemistry

Silver-based catalysts have been extensively investigated as the platinum substituted catalysts due to their high catalytic efficiency, low cost and long-term durability. In this study, the surfactant-free silver nanoparticles supported on graphene quantum dots were synthesized through a facile approach without addition of any other protecting ligands and reducing agents. The “surface-clean” silver nanoparticles had remarkable electrocatalytic performance towards oxygen reduction reaction (ORR) with the most efficient four-electron transfer process. Compared with commercial Pt/C catalyst, the hybrid nanoparticles showed comparable catalytic performance for ORR but much higher tolerance to methanol. Such silver nanoparticles supported on graphene quantum dots may have …

Electrochemical Fabrication Of Two-Dimensional Flower-Like Pt Nanostructures For Methanol Electrocatalytic Oxidation, Xia Wang, Jun Hu, Yong-Jun Li

Journal of Electrochemistry

Two-dimensional flower-like Pt nanostructures (2D FPNs) were fabricated on glassy carbon substrates by galvanostatical electrochemical technique. The electrolyte was the HAuCl₄ + HClO₄ aqueous solution without addition of any structure-directing organic reagent, which made as-prepared Pt nanostructures cleaner, exhibiting much higher reactivity. Scanning electron microscopic images revealed that 2D FPNs were spherical Pt nano-flowers constructed by the smallest building blocks, nano-leaves. The number density of spherical Pt nano-flowers can be tuned by controlling the electrodeposition time. High resolution transmission electron microscopic images indicated that each nano-leaf was formed by growing along Pt(111) direction. Electrocatalytic activities of as-prepared 2D …

Effecting Of Dissolved Oxygen On Microbial Fuel Cells Based On Pseudomonas Aeruginosa, Chang-Li Cao, Li-Xiang Chen, Ran-Ran Wu, Ken-Lin Chang, Feng Zhao

Journal of Electrochemistry

In this work, the reaction between the electron shuttle secreted by Pseudomonas aeruginosa and anode was studied by measuring cyclic voltammogram and open circuit potential. The effect of dissolved oxygen on the oxidation reaction of anode was explored. It was demonstrated that the reaction was a diffusion-controlled and reversible process. The anode was a little affected when the dissolved oxygen of inocula was low (0 ~ 1.6 mg·L^-1). The polarization curves showed that the current output of microbial fuel cells decreased 7% with the impact of dissolved oxygen.

Recent Progress In The Mechanistic Understanding Of Formic Acid Oxidation On Pt Electrode, Jie Xu, Dao-Chuan Jiang, Dong Mei, Zheng-Da He, Yan-Xia Chen

Journal of Electrochemistry

This article reviews the recent progress in understanding of the mechanisms for formic acid oxidation on Pt electrode. There are two pathways for formic acid oxidation on Pt electrode: (1) Indirect Pathway through which HCOOH is oxidized to CO₂ through CO_ad intermediate. This pathway contributes only 1% of the total current; (2) Direct Pathway where HCOOH is oxidized directly to CO₂. The results from IR Spectroscopy, single-crystal electrochemistry and DFT calculation all support that the bridge-bonded formate is neither the intermediate of direct pathway nor the precursor for CO_ad formation in indirect pathway. Possible mechanism …

Preparation Of Pt-Tio2/Graphene Composites With High Catalytic Activity Towards Methanol Oxidation And Oxygen Reduction Reaction, Li Qi, Ying Yin, Wen-Guang Tu, Bing-Bing Wu, Zhao-Sheng Wang, Jian-Guo Liu, Jun Gu, Zhi-Gang Zou

Journal of Electrochemistry

A series of graphene-supported TiO₂ nanoparticles (TiO₂/G) with different TiO₂ contents were prepared by a facile hydrothermal method, and then the Pt-TiO₂/G catalysts were successfully prepared by reducing Pt-precursor with microwave technique. Compared with Pt-G catalysts, the catalytic performance toward oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) of Pt-TiO₂/G catalysts was improved due to the addition of TiO₂. However, the excessive TiO₂ would lead to a poor catalytic performance of Pt-TiO₂/G catalysts because of the low electrical conductivity of TiO₂.

Does A Plastron Improve Heat Transfer?, Madani A. Khan, Jeffrey Alston, Andrew Guenthner

STAR Program Research Presentations

Superamphiphobic surfaces strongly repel both water and oils. In this work, aluminum coupons are processed by sanding with various grit of sand paper to impart microscale roughness. Subsequent submersion of the aluminum substrate in boiling water grows nanoscale grass-like structures. The oxide layer of Al is slightly soluble in water. During a fast diffusion/equilibrium, Al₂O₃ nanograss grows on the surface. A low energy coating is then deposited on the surface. The micro and nanoscale features create re-entrant structures that trap air enabling contact liquid to be in a Cassie-Baxter state. Superamphiphobicity of the samples were confirmed by …

Persistent Hepatic Structural Alterations Following Nanoceria Vascular Infusion In The Rat, Michael T. Tseng, Qiang Fu, Khoua Lor, G. Rafael Fernandez-Botran, Zhong-Bin Deng, Uschi M. Graham, D. Allan Butterfield, Eric A. Grulke, Robert A. Yokel

Chemistry Faculty Publications

Understanding the long-term effects and possible toxicity of nanoceria, a widely utilized commercial metal oxide, is of particular importance as it is poised for development as a therapeutic agent based on its autocatalytic redox behavior. We show here evidence of acute and subacute adverse hepatic responses, after a single infusion of an aqueous dispersion of 85 mg/kg, 30 nm nanoceria into Sprague Dawley rats. Light and electron microscopic evidence of avid uptake of nanoceria by Kupffer cells was detected as early as 1 hr after infusion. Biopersistent nanoceria stimulated cluster of differentiation 3⁺ lymphocyte proliferation that intermingled with nanoceria-containing …

Fundamental Studies On Copper Zeolites For Catalytic No X Abatement, Anuj Arun Verma

Open Access Dissertations

Stringent regulations in mobile NOx emissions have resulted in the development of Standard Selective Catalytic Reduction (SCR) as the dominant NOx abatement technology in lean burn diesel engines. Standard SCR is a reaction of nitric oxide (NO) with ammonia (NH₃), in the presence of oxygen (O ₂) to form nitrogen (N₂) and water (H₂O). Copper containing zeolites show commercially viable SCR performance. Cu-SSZ-13 (CHA framework), a member of this family, is a preferred catalyst for SCR applications because it shows exceptional hydrothermal stability in addition to commercially viable SCR performance. Our work focuses …

Preparation & Characterization Of High Purity Cu2 Znsn(Sxse1-X)4 Nanoparticles, Bethlehem G. Negash

Open Access Theses

Research in thin film solar cells applies novel techniques to synthesize cost effective and highly efficient absorber materials in order to generate electricity directly from solar energy. Of these materials, copper zinc tin sulfoselenide (Cu₂ZnSn(S_xSe_1-x) ₄) nanoparticles have shown great promise in solar cell applications due to optimal material properties as well as low cost & relative abundance of materials.^1,2 Sulfoselenide nanoparticles have also a broader impact in other industries including electronics³, LED ⁴, and biomedical research⁵. Of the many routes of manufacturing these class of semiconductors, …

Correlating Molecular Architecture Of A Radical Polymer Based Copolymer With Its Electrical Transport Properties, Holly Chan

Open Access Theses

The design and synthesis of electrically-conductive macromolecules can lead to significant improvements in the performance of polymer-based energy conversion devices (e.g., thermoelectric devices). For these organic electronic devices, conjugated polymers have dominated the area of conductive polymers; however, these materials are usually synthesized using conditions that lead to poorly-defined polymers. Furthermore, in these increasingly-standard polymers, the charge transport ability of the polymer thin films is largely affected by the degree of crystallinity, which is a difficult property to control in a reproducible fashion. Therefore, we seek to explore a new class of amorphous, non-conjugated polymers containing a stable radical …

Horseradish Peroxidase-Attapulgite Clay Nanocomposites: Fabrication And Application To Sensing The Extracellular H2O2 Released From Cells, Ping Wu, Chen-Xin Cai

Journal of Electrochemistry

The nanostructured attapulgite clay was employed as a support matrix for immobilizing horseradish peroxidase (HRP). FTIR and electrochemical methods demonstrated that HRP had been effectively assembled on attapulgite surface with the formation of HRP-attapulgite nanocomposites. The HRP-attapulgite hybrid was deposited on the glassy carbon (GC) electrode forming the HRP-attapulgite/GC electrode. Cyclic voltammetric results showed a pair of well-defined redox peaks, which were ascribed to direct electron transfer (DET) of HRP, with the formal potential E₀′ = -335 mV (vs. SCE) in the phosphate buffer solution (PBS, pH 7.0). The dependence of E₀′ on solution pH indicated …

The Ionic Diffusion Model For The Solid Oxide Cathode And Its Verification By The Electrolysis Of Ta2O5 In Molten Cacl2, Hua-Lin Chen, Zhi-Yong Wang, Xian-Bo Jin, George Z. Chen

Journal of Electrochemistry

The deoxidation speed of a solid oxide cathode in molten CaCl₂ can be estimated by the PRS steady diffusion model of O^2-, which correlates the deoxidation speed with the precursor porosity, P, the metal-to-oxide molar volume ratio, R, and the cathode volume shrinkage S. The PRS model indicates that the porosity of the oxide cathode has important influence on the deoxidation speed, and provides a very simple equation for the prediction of the optimal cathode porosity. For the electrolysis of Ta₂O₅, the porosity of the cathode is better to be within 50%. …

Effects Of Oxygen Coverage And Hydrated Proton Model On The Dft Calculation Of Oxygen Reduction Pathways On The Pt(111) Surface, Li-Hui Ou, Sheng-Li Chen

Journal of Electrochemistry

DFT calculation is used to study various possible steps in the oxygen reduction reaction (ORR), including the adsorption and dissociation process of O₂ and the serial protonation process of dissociated products to form H₂O on the Pt(111) surface. By using slabs of different sizes, and different numbers of pre-adsorbed oxygen atoms, the coverage effects on the pathways are investigated. The calculated results using different hydrated proton models are also compared. It is shown that the initial step of the ORR is the formation of a protonated end-on chemisorbed state of OOH*, which can transform to an unprotonated …

Reduction Of Ketoximes To Amines By Catalytic Transfer Hydrogenation Using Raney Nickel And 2-Propanol As Hydrogen Donor, Katherynne E. Taylor

Honors Theses

Ketoximes successfully underwent hydrogenolysis and hydrogenation under catalytic transfer conditions with Raney Nickel and 2-propanol as a hydrogen donor. Ketoximes were reduced to primary amines when 2% KOH was included in the reaction. In the absence of KOH N-isopropyl-secondary-amines were obtained in good yields.

Study Of The Structure-Property Relationships That Determine The Effects Of Latexes And Starch Containing Latex Emulsions On The Performance Of The Barrier Coatings (Sub-Coat) For Paper, Joanna Marie Monfils

Master's Theses

The history of carbonless paper dates back to the 1940s. Before this, a carbon copy sheet was needed between sheets of paper to be able to produce one or more copies simultaneously during writing. The pressure from a pen or typewriter would help deposit the ink of the carbon paper onto the blank sheet of paper under the original written sheet to create a “carbon copy.” This method did however, have its disadvantages. Not only did it produce a limited number of copies, but it was also a messy process. So came the creative process of using microencapsulated dyes to …

Homochiral Metal-Organic Materials: Design, Synthetic And Enantioseletive Separation, Shi-Yuan Zhang

USF Tampa Graduate Theses and Dissertations

Owing to the growing demand for enantiopurity in biological and chemical processes, tremendous efforts have been devoted to the synthesis of homochiral metal-organic materials (MOMs) because of their potential applications in chiral separation and asymmetric catalysis. In this dissertation, the synthetic strategies for homochiral MOMs are discussed keeping the focus on their applications. Two distinct approaches have been taken to synthesize chiral structures with different topologies and accessible cavities. The chiral MOMs have been utilized in enantioselective separation of racemates.

Chiral variants of the prototypal metal-organic framework MOF-5, δ-CMOF-5 and [lambda]-CMOF-5, have been synthesized by preparing MOF-5 in the presence …

Electrocatalytic Oxidation Of Glycerol At The Platinum Electrode Modified With An Nd-Fe-Moo42- Cyano-Bridged Mixed Coordination Polymer, Yong-Jun Ma, Yu-Xiu Tian, Jing Liu, Min Zhou, Jing Ding, Zhi-Mei Jin, Xiang-Mei Wang

Journal of Electrochemistry

A platinum electrode decorated with the ordered Nd-Fe-MoO₄^2- cyano-bridged mixed coordination polymer was successfully prepared by electrodeposition in virtue of the lyotropic liquid crystal soft template methods, and electrocatalytic oxidation behavior of glycerol was investigated on the chemically modified electrode by cyclic voltammetry. The influences of experimental factors such as the concentrations of H⁺ and SO₄^2- in electrolytes, glycerol concentration and scan rate on the electrocatalytic activity of glycerol at the modified electrode were also studied. It indicated that the proper amount of SO₄^2- in weakly acidic electrolyte could help to improve the …

Synthesis Of Platinum Nanocrystallites And Possible Electrocatalytic Properties For Methanol, Lei-Lei Lu, Bao-Zhong Du, Sha Sun, Jin-Fen Niu, Jie Zhao

Journal of Electrochemistry

Platinum nanocrystallites were synthesized by the colloidal method using oxamide as the stabilizer. The morphologies and electrocatalytic performances for methanol of platinum nanocrystallites prepared at different pH values and with different reactant ratios of precursor and stabilizer were investigated. It was found that the platinum nanocrystallites synthesized at pH=5 and with the reactant ratio of 1:20 showed the best electrocatalytic activity for methanol. The peak current density reached up to 1709 μA·cm^-2. Furthermore, the electrocatalytic activity of platinum nanocrystallites for methanol reduced significantly although the cyclic voltammograms in the blank solution were not obviously changed after exposing in …

Effect Of Temperature On The Self-Humidifying Open-Cathode Proton Exchange Membrane Fuel Cell, Si-Chen Zhao, Ben Wang, Qiu-Hong Jia, Ming Han, Yu-Hong Xie

Journal of Electrochemistry

Based on the experiments about the output characteristics of a home-made temperature-controlled PEMFC system with atmospheric pressure and no external humidifying condition in different loading voltages and operating temperatures, the optimum operating temperature at different loading voltages can be obtained by tracking the output characteristics of PEMFC operating over a range of temperatures. By analyzing the fitted data the kinetic parameters are evaluated and the effect of different operating temperatures on the PEMFC performance is discussed from a view of electrode kinetics.

Preparation Of Pt/H-Tio2 Catalyst With Improved Catalytic Performance For Methanol Electrooxidation, Jin Han, Zhi-You Zhou, Qiang Wang, Miao-Qiang Lv, Chi Chen, Shi-Gang Sun

Journal of Electrochemistry

White TiO₂ nanorods were synthesized by hydrothermal method with TiCl₄ as a precursor. As-synthesized TiO₂ nanorods were further subjected to high-temperature (550 ^oC) heat treatment for 2 h under H₂ atmosphere to prepare gray black hydrogen-treated TiO₂ (H-TiO₂) nanorods with oxygen vacancies and Ti³⁺ interstitial atoms. The Pt nanoparticles of 1.9 nm were supported on these two types of TiO₂ nanorods to form Pt/TiO₂ and Pt/H-TiO₂ catalysts. XRD data indicates that the crystal structure of TiO₂ was still reserved as rutile after hydrogen treatment, but the surface …

Electro-Catalytic Oxidation Of Hydrogen Peroxide On Au/ L-Methionine /Gc Electrode, Jian-Feng Fan, Xue-Mei Luo, Jing Li, Lou-Zhen Fan

Journal of Electrochemistry

The modified electrodes have been fabricated by generation of Au nanoparticle chains, which was produced by reaction between HAuCl4 and sodium citrate without any additional capping agents or surfactants. The self-assembled Au nanoparticles were attached to the surface of glassy carbon electrode (GCE) layer by layer, using L-methionine (L-Met), thiourea (TU), allyl thiourea (ATU) and polyvinylpyrrolidone (PVP) as a crosslinking agent, respectively. The experimental results showed that the electrochemical performance of the different modified electrodes varied in [Fe(CN)₆]^3-/4- solution. The Au/L-Met/GCE exhibited an excellent electrochemical property, which is superior to other modified electrodes. In addition, the catalysis …

Pulse Electrodeposition Of Pd-Ni Alloy Nanoparticles For Electrocatalytic Oxidation Of Formic Acid, Fang-Zu Yang, Jun-Pei Yue, Zhong-Qun Tian, Shao-Min Zhou

Journal of Electrochemistry

The Pd-Ni alloy nanoparticles with nickel atomic contents of 12.0%, 16.4% and 22.6% were successfully electrodeposited from a Pd-Ni alloy electrolyte by square wave pulse plating. The alloy nanoparticles were in the spherical shape with a diameter of 50 ~ 80 nm. As the growth potential of the alloy was negatively shifted, the nickel content of the alloy was increased, and the size of the nanoparticles was almost the same, whereas the number, the degree of crosslinking and the real active area of the nanoparticles were increased. As the nickel content of the alloy nanoparticles increased, the peak current for …

Fabrication And Impedance Performance Of Gradient Lani0.6Fe0.4O3-δ-Gd0.2Ce0.8O2 Composite Cathodes For Intermediate Temperature Solid Oxide Fuel Cell, Yang Li, Bo Huang, Meng Yuan, Zhi-Qiu Zhang, Zong-Yao Liu, Xu-Chen Tang, Xin-Jian Zhu

Journal of Electrochemistry

A LNF-GDC composite cathode with a gradual change in the composition between ScSZ electrolyte and LNF cathode was fabricated to reduce the cathode polarization resistance (R_p). The gradual change in composition between ScSZ electrolyte and LNF cathode shows the decreases in the charge transfer resistance (R_ct) and gas phase diffusion resistance (R_d). The results revealed that the Rp value, measuring 0.452 Ω·cm² at 750 °C, was the lowest for LNF-GDC composite cathodes with three layers and gradient changes in composition between ScSZ and LNF (Cathode C),, whereas the Rp value of 70%LNF-30%GDC composite …

Study On Carbon Supported Pd Catalysts Modified By Phosphomolybdic Acid For H2O2 Electrocatalytic Reduction, Li-Mei Sun, Cheng Zhang, Ying-Rong Bao, Hong-Xia Li

Journal of Electrochemistry

The Pd/C catalyst was prepared with the chemical reduction method, and phosphomolybdic acid (PMA) was modified on the Pd/C catalyst using the dipping method. The compositions and structures of the Pd/C and Pd/C modified by phosphomolybdic acid (PMA-Pd/C) catalysts were characterized with X-ray diffraction and Fourier Transform infrared spectroscopy analyses. The electrocatalytic activity and stability of the catalysts for the reduction of hydrogen peroxide (H₂O₂) were studied using cyclic voltammetry and chronoamperometry. The results showed that the phosphomolybdic acid was tightly fixed on the surface of Pd/C catalyst through the chemical interaction. The eletrocatalytic activity of …

Synthesis And Electrochemical Properties Of Lico1-XMgXMno4 And Lico1-XAlXMno4 (X= 0, 0.02, 0.05, 0.1) As Positive Materials For Lithium-Ion Batteries, Mei-Ling You, Qing-Song Tong, Xiu-Hua Li, Min Lin, Xing-Kang Huang, Yong Yang

Journal of Electrochemistry

The Al-doped and Mg-doped LiCoMnO₄ materials were synthesized through solid-state reaction. The effects of doping amounts of Mg and Al on the initial capacities, discharge plateaus, and cycle performances were investigated. The morphologies and structures of the as-prepared materials were studied by scanning electron microscopy and powder X-ray diffraction. The results indicate that the as-prepared samples were composed of uniform, well-crystallized particles. The pristine LiCoMnO₄ possessed an initial capacity of 87.0 mAh·g^-1, while LiCo_0.98Mg_0.02MnO₄ and LiCo_0.98Al_0.02MnO₄ delivered 91.3 and 93.6 mAh·g^-1, respectively. The proper …