Chemistry Commons^™

Characterization Of Biochars Produced From Peanut Hulls And Pine Wood With Different Pyrolysis Conditions, James W. Lee, Bob Hawkins, Michelle K. Kidder, Barbara R. Evans, A. C. Buchanan, Danny Day

Chemistry & Biochemistry Faculty Publications

Background

Application of modern biomass pyrolysis methods for production of biofuels and biochar is potentially a significant approach to enable global carbon capture and sequestration. To realize this potential, it is essential to develop methods that produce biochar with the characteristics needed for effective soil amendment.

Methods

Biochar materials were produced from peanut hulls and pine wood with different pyrolysis conditions, then characterized by cation exchange (CEC) capacity assays, nitrogen adsorption–desorption isotherm measurements, micro/nanostructural imaging, infrared spectra and elemental analyses.

Results

Under a standard assay condition of pH 8.5, the CEC values of the peanut hull-derived biochar materials, ranging from …

Synthesis Of Porous Carbon Nanosheets And Its Application In Sodium-Ion Battery, Jing-Fei Zhang, Jing Lu, Xiao-Yu Yang, Yun-Di Huang, Lin Xu, Dong-Mei Sun, Ya-Wen Tang

Journal of Electrochemistry

Owning to sodium’s high abundance, relatively low cost, similar chemical properties to Li and very suitable redox potential of E₀(Na⁺/Na) = -2.71 V versus SHE which is only 0.3 V above that of lithium, rechargeable sodium ion battery hold much promise as potential alternatives to current lithium ion batteries for energy storage applications. Carbon material is regarded as the most promising anode candidate for sodium ion battery. Particularly, carbon nanosheet with porous structure and high conductivity is expected to have improved sodium ion storage properties. In this paper, we present a two-step pyrolysis-based method for facile …

Applying Bayesian Machine Learning Methods To Theoretical Surface Science, Shane Carr

McKelvey School of Engineering Graduate Student Theses & Dissertations

Machine learning is a rapidly evolving field in computer science with increasingly many applications to other domains. In this thesis, I present a Bayesian machine learning approach to solving a problem in theoretical surface science: calculating the preferred active site on a catalyst surface for a given adsorbate molecule. I formulate the problem as a low-dimensional objective function. I show how the objective function can be approximated into a certain confidence interval using just one iteration of the self-consistent field (SCF) loop in density functional theory (DFT). I then use Bayesian optimization to perform a global search for the solution. …

Hybrid Aryl-Ether-Ketone And Hyperbranched Epoxy Networks, John Misasi

Dissertations

In this dissertation, relationships between chemical structures, cure kinetics and network architectures are correlated to bulk mechanical properties for novel, hybrid epoxy-amine networks. The work is split into two primary sections: the first is the synthesis and characterization of multifunctional glassy networks based on aryl-ether-ketone diamine curatives, while the second is based on the synthesis and characterization of hyperbranched epoxy polymers and their resulting networks.

Three aryl-ether-ketone (AEK) diamines of increasing molecular weights were synthesized and used to cure 4,4’-tetraglycidylether of diaminodiphenylmethane (TGDDM); the resulting networks were compared to 4,4’-diaminodiphenyl sulfone cured TGDDM. Architectural differences were created by varying cure …

Production And Harvest Of Microalgae In Wastewater Raceways With Resource Recycling, Alexander Colin Roberts

Master's Theses

Microalgae can be grown on municipal wastewater media to both treat the wastewater and produce feedstock for algae biofuel production. However the reliability of treatment must be demonstrated, as well as high areal algae productivity on recycled wastewater media and efficient sedimentation harvesting. This processes was studied at pilot scale in the present research.

A pilot facility was operated with nine CO₂-supplemented raceway ponds, each with a 33-m² surface area and a 0.3-m depth, continuously from March 6, 2013 through September 24, 2014. The ponds were operated as three sets of triplicates with two sets continuously fed …

Preparations And Properties Of Polybenzimidazole/Polyvinylbenzyl Crosslinked Composite Membranes For High Temperature Proton Exchange Membrane Fuel Cells, Jin-Kai Hao, Yong-Yi Jiang, Zhen Wang, Xiao-Jin Li, Zhi-Gang Shao, Bao-Lian Yi

Journal of Electrochemistry

In order to increase the chemical stability of polybenzimidazole (PBl) membrane, a highly stable polymer, poly vinyl. benzyl chloride (PVBC), was chosen as the macromolecular crosslinker, and 1H-1,2,4-triazol was adopted to prepare the crosslinked PBI-based membranes. The influence of the PVBC amount on membrane characteristic was investigated in detail. The results indi. cated that the crosslinked structure of the membrane effectively improved the chemical stability, and at the same time, the mem. brane presented good mechanical property and proton conductivity. The fuel cell performance for the membrane was tested with hy. drogen and oxygen single cell without humidification at 150 …

Highly Selective Hydrogenation And Hydrogenolysis Using A Copper-Doped Porous Metal Oxide Catalyst, Laurene Petitjean, Raphael Gagne, Evan Beach, Dequan Xiao, Paul Anastas

Chemistry and Chemical Engineering Faculty Publications

A copper-doped porous metal oxide catalyst in combination with hydrogen shows selective and quantitative hydrogenolysis of benzyl ketones and aldehydes, and hydrogenation of alkenes. The approach provides an alternative to noble-metal catalysed reductions and stoichiometric Wolff-Kishner and Clemmensen methods.

Synthesis, Characterisation, Electrochemical, And Spectroscopic Studies Of Cobaloximes: Unique Clues Of Cobalt(I) Species In Various Solvents, Michael John Celestine

Chemistry & Biochemistry Theses & Dissertations

With the dwindling amount of fossil fuels in the world’s reserve is said to run out in the future. The use of alternative fuels such as hydrogen can be produced from renewable sources. One source is the use of first row transition metal complexes that can harness the power of the sun to reduce protons to hydrogen. In this thesis we investigated a well-known hydrogen evolution catalyst in a quest to understand the behavior of different oxidation states that occur during the catalytic cycle.

In an attempt to synthesize a binuclear ruthenium(II) complex, [{Ru(phen)2}2{µmes(1,4-phO-Izphen)3}](PF6)4, as a possible photosensitizer for the …

Effect Of Adsorption Potential On Co Oxidation At Au@Pt Nanoparticles Electrodes, A Surface Enhanced Raman Spectroscopic Study, Pu Zhang, Yi Wei, Yong-Li Zheng, Yan-Xia Chen, Zhong-Qun Tian

Journal of Electrochemistry

The adsorption/oxidation of CO on the 55 nm [email protected] nm Pt nanoparticles electrode in both potentiodynamic and potentiostatic modes were investigated by surface enhanced Raman spectroscopy in a thin layer electrochemical flow cell under controlled mass transport, with the aim of clarifying the origin CO oxidation at lower electrode potentials (in current pre-wave region of corresponding cyclic voltammograms). Our results demonstrated that the CO oxidation kinetics differed significantly from the three kinds of different CO adsorption history, with almost no CO oxidation current in the pre-peak potential region after 0.35 V_RHE CO adsorption with or without subsequent holding the …

Synthesis And Electrochemical Performance Of Mn3O4/Graphene Composites, Shan-Shan Yang, Qian Zhang, Xiong-Gui Lin, Ming-Sen Zheng, Quan-Feng Dong

Journal of Electrochemistry

The Mn₃O₄/Graphene composites were synthesized by hydrothermal method with the in-situ redox reaction of graphene oxide (GO) and manganese acetate (Mn(Ac)₂). The phase structures and morphologies of the materials were characterized by XRD, SEM and TEM. The XPS and IR techniques were used for studying the residual function groups of reduced graphene oxide (RGO). The electrochemical performances of the hybrids were tested in a coin cell. Results showed that the composites prepared with the addition of ammonia water (RM-A) have better performance. The graphenes in RM-A were better-reduced and the Mn₃O_{4 …}

Synthesis, Structure And Electrochemical Performance Of Na2Mnsio4/C Cathode Material For Na-Ion Batteries, Shou-Ding Li, Jiang-Huai Guo, Yong Xie, Jin-Xiao Mi, Yong Yang

Journal of Electrochemistry

As a promising cathode material for sodium ion batteries, pure phase Na₂MnSiO₄/C nanocomposite was successfully synthesized by a sol-gel method with a citric acid as a complex agent. The as prepared material was characterized by XRD, FTIR, SEM and TEM techniques. XRD and Rietveld refinement results indicated that the sample was indexed as monoclinic structure with space group of Pn. It was observed by SEM and TEM that the obtained product consisted of micro-scaled secondary particles, which were composed of NaMnSiO₄ nanocrystallites and amorphous carbon network. More importantly, the uniform carbon network in the …

Tungsten Carbide/Carbon Electrode Material Synthesized By Block Copolymer Template Method, Xiao-Ling Lang, Ye-Kun Jiang, Mei-Qin Shi, Ling-Zhi Kang, Chun-An Ma

Journal of Electrochemistry

At present, one of the major hurdles for commercialization of system with direct methanol fuel cell (DMFC) is still the requirement of a significant amount of platinum (Pt) catalyst to achieve an acceptable power density. Pt and Pt-based metals are expensive due to limited supplies. In order to find the catalyst alternative to the Pt metal, we selected tungsten carbide (WC) and its composites as the study object. We synthesized WC with carbon materials as the suitable support to modify the electronic structure and to increase the specific surface area of WC. In this study, tungsten carbide/carbon (WC/C) was prepared …

Mechanism Study On The Electrocatalytic Oxidation Of Acetylene To Oxalic Acid, Xiu-Li Song, Rui-Long Jia, Wen-Yan Dong, Zhen-Hai Liang

Journal of Electrochemistry

A new method of electrocatalytic synthesis oxalic acid from acetylene was explored and the synthesized oxalic acid was characterized by Ultraviolet-visible spectrophotometry (Uv-vis) and Infrared spectroscopy (IR). First-principles calculations were carried out to examine the adsorption of acetylene over the Pt(111) surface. The electrocatalytic oxidation behavior of acetylene has been investigated on a Pt electrode by cyclic voltammetry (CV) and steady-state polarization in Na₂SO₄ solution. The formation mechanism of oxalic acid in the Na₂SO₄ solution was proposed and the transfer coefficients of the reaction were calculated. The results show that acetylene molecule tends to …

Preparation And Characterization Of Carbon Supported Pd-Sb Composite Nanocatalysts For Formic Acid Electrooxidation, Long-Long Wang, Xiao-Lu Cao, Ya-Jun Wang, Jin-Hao Ping, Qiao-Xia Li

Journal of Electrochemistry

Palladium is considered as an efficient anode catalyst with high catalytic activity for electrooxidation of formic acid. To further improve the catalytic activity and stability, alloying or surface modification with Sb is an effective way. In this work, the well dispersed carbon supported Pd-Sb composite nanocatalysts (Pd-Sb/C) were synthesized by traditional impregnation reduction method with trisodium citrate as the complexing agent, sodium borohydride as the reducing agent. The morphologies of Pd-Sb/C and the effects of molar ratio of Pd to Sb on the electrocatalytic properties of Pd-Sb/C for HCOOH electrooxidation were studied. The XRD and XPS analyses on the as-prepared …

Effect Of Carbon Nanotubes On Anodic Properties Of Ti/Ru-Ir-Sn Oxides, Feng Lian, Yong-Lei Xin, Bo-Jiang Ma, Li-Kun Xu

Journal of Electrochemistry

The Ru-Ir-Sn metal oxide anodes coated on titanium (Ti/Ru-Ir-Sn) were prepared by thermal decomposition. The effects of amounts of carbon naotubes (CNTs) on anodic properties were studied by TGA, SEM, EDS, cyclic voltammetry, EIS, polarization measurements and accelerated life test. The thermogravimetric analysis and EDS spectrum data showed that the high temperature oxidation decomposition of CNTs did not take place under the condition of the sintering temperature of 470 ℃, and the CNTS still existed in the anode coating in an element form. Compared with the contrast samples, the surface crack of the coating increased, but remained typical morphology. Adding …

Analysis Of The Fabrication Conditions In Organic Field-Effect Transistors, Rachel M. Rahn, Yan Zhao, Jianguo Mei

The Summer Undergraduate Research Fellowship (SURF) Symposium

Polymer-based organic field-effect transistors have raised substantial awareness because they enable low-cost, solution processing techniques, and have the potential to be implemented in flexible, disposable organic electronic devices. The performance of these devices is highly dependent on the processing conditions, as well as the intrinsic properties of the polymer. Processing conditions play an important role in semiconductor film formation and device performance. These factors may provide an important link between structure and performance. In this study, an empirical analysis tool, Process Scout, was applied to assess processing factors such as polymer concentration and silicon modification. This sanctioned the creation of …

Synthesis, Characterization, And Thermoelectric Properties Of Radical Siloxanes, Arnold J. Eng, Bryan Boudouris, Edward P. Tomlinson, Martha Emily Hay

The Summer Undergraduate Research Fellowship (SURF) Symposium

More than half of the annual energy consumption in the United States is lost as waste heat. Polymer-based thermoelectric devices have the potential to utilize this waste heat both sustainably and cost-effectively. Although conjugated polymers currently dominate research in organic thermoelectrics, the potential of using polymers with radical pendant groups have yet to be realized. These polymers have been found to be as conductive as pristine (i.e., not doped) poly(3-hexylthiophene) (P3HT), a commonly-used charge-transporting conjugated polymer. This could yield promising avenues for thermoelectric material design as radical polymers are more synthetically tunable and are hypothesized to have a high Seebeck …

Secondary Organic Aerosol Formation From The Β-Pinene+No3 System: Effect Of Humidity And Peroxy Radical Fate, C. M. Boyd, J. Sanchez, L. Xu, Alexis J. Eugene, T. Nah, W. Y. Tuet, Marcelo I. Guzman, N. L. Ng

Chemistry Faculty Publications

The formation of secondary organic aerosol (SOA) from the oxidation of β-pinene via nitrate radicals is investigated in the Georgia Tech Environmental Chamber (GTEC) facility. Aerosol yields are determined for experiments performed under both dry (relative humidity (RH) < 2 %) and humid (RH = 50 % and RH = 70 %) conditions. To probe the effects of peroxy radical (RO₂) fate on aerosol formation, "RO₂ + NO₃ dominant" and "RO₂ + HO₂ dominant" experiments are performed. Gas-phase organic nitrate species (with molecular weights of 215, 229, 231, and 245 amu, which likely correspond to molecular formulas of C₁₀H₁₇NO₄, C₁₀H₁₅NO₅, C₁₀H₁₇NO …

Synthesis Of Graphene Wrapped Li-Rich Layered Metal Oxide And Its Electrochemical Performance, Meng-Yan Hou, Ke Wang, Xiao-Li Dong, Yong-Yao Xia

Journal of Electrochemistry

In present work, lithium-rich layered transition metal oxide (LLO) was synthesized by a co-precipitation method in combination with a solid-state reaction. The graphene wrapped Li-rich layered oxide composite (LLO/Gra) was obtained by sintering the LLO/GO composite at 300 ^oC for 30 min in an air. The morphologies and the electrochemical performances were characterized by means of SEM, TEM, XRD, XPS, EIS and charge/discharge tests. The results indicated that the LLOe particles were uniformly wrapped with graphene. The resulting material exhibited better rate capability than that of pristine LLO since the wrapped graphene demonstrated the enhanced electronic conductivity. Accordingly, the …

Enhancing Stability Of Pem Fuel Cell Catalysts Via Support Changing, Xiao-Hong Xie, Zi-Dong Wei

Journal of Electrochemistry

The Pt/C catalyst with highly dispersed Pt nanoparticles supported on carbon has been widely used as the state-of the-art catalyst in proton exchange membrane fuel cells (PEMFCs), while the durability of Pt/C is one of the major barriers for large-scale applications of PEMFCs. Thus, enhancing the stability of Pt/C has been a hot issue in this field. In this review, we summarize the recent progress in enhancing the catalyst stability in the view of support material. The future prospects of the PEMFCs catalyst should focus on adopting more stable supports or strengthening the interactions between Pt and supports.

Pt/C Modified Proton Exchange Membrane For Improved Fuel Cell Performance, Zhi Cui, Chao Wang, Shui-Yun Shen, Feng-Jing Jiang, Jun-Liang Zhang

Journal of Electrochemistry

The property of proton exchange membrane greatly affects the performance of proton exchange membrane fuel cells (PEMFC). During the operation of a PEMFC, the water produced at the cathode, the water vapor from the humidified feed gas and the water migrated by electro-dragging will reach a balance in the membrane and determine the resistance of PEMFC, and thus affect the performance of PEMFC. Normally, the PEMFC performance strongly depends on the relative humidity of the feed gas, and the performance decreases at lower humidity as a result of lower proton conductivity of the membrane. In this paper, we proposed to …

Recent Research Progress For Non-Pt-Based Oxygen Reduction Reaction Electrocatalysts In Fuel Cell, Ping Song, Ming-Bo Ruan, Jing Liu, Guang-Jun Ran, Wei-Lin Xu

Journal of Electrochemistry

The expensive Pt-based catalyst suffers from its susceptibility to time-dependent drift, methanol crossover, and carbon monoxide (CO) deactivation, which will block the large-scale commercial application of fuel cells. It is, therefore, necessary to develop efficient, low-cost, highly stable non-precious metal oxygen reduction reaction (ORR) catalysts with high catalytic performance. Here, we will pay attention to the research progress of non-precious metal and heteroatom-doped (N, B, P, S, F) metal-free ORR catalysts. Importantly, we mainly focus on the work developed by Xu’s group with the Fe-based non-precious metal and F/NF-doped metal-free ORR catalysts. The purpose of these works is to improve …

Preparation And Properties Of Binary Oxides CoXCr1-XO3/2 Electrocatalysts For Oxygen Evolution Reaction, Tai-Lai Yang, Wen-Yan Dong, Hui-Min Yang, Li Zhang, Zhen-Hai Liang

Journal of Electrochemistry

Binary metal mixed oxides of Co and Cr with nominal compositional formulas, Co_xCr_1-xO_3/2 (x=0, 0.2, 0.4, 0.6, 0.8 and 1.0), were obtained by thermal decomposition method. The morphologies, crystal forms and valence states of the catalyst powders were analyzed by SEM, XRD and XPS, respectively. And the electrochemical properties, overpotentials and stabilities of Co_xCr_1-xO_3/2 electrodes for oxygen evolution reaction (OER) in an alkaline solution were evaluated by linear sweep voltammetry (LSV), staircase voltammetry and chronoamperometry, respectively. The results indicated that the mixtures of Co₃O₄ and eskolaite-Cr_{2 …}

Synthesis And Electrochemical Properties Of Cnts/V2O5 Hollow Microspheres, Liang Hao, Lai-Fa Shen, Jie Wang, Jia-Jia Zhu, Xiao-Chen Zhao, Xiao-Gang Zhang

Journal of Electrochemistry

The carbon nanotubes/vanadium oxides (CNTs/V₂O₅) hollow microspheres (VOC) were prepared via solvothermal process. The effects of the ratio for CNTs to V₂O₅ on the morphologies, structures and electrochemical performances were systemically investigated. The results indicate that CNTs dramatically enhanced the rate performances of VOC composite electrodes. When the ratio of CNTs is 7.1%, the VOC composite electrode exhibited the best electrochemical performance, which delivered a specific capacitance of 346 F·g^-1 at 0.5 A·g^-1 and maintained 75% at 8 A·g^-1 in 5 mol L^-1 LiNO₃. A hybrid capacitor …

Porous Co3O4 Hollow Nanospheres Cathode Catalyst For High-Capacity And Long-Cycle Li-Air Batteries, Tong Liu, Na Li, Qing-Chao Liu, Xin-Bo Zhang

Journal of Electrochemistry

In this paper, a high specific surface area of porous Co3O4 hollow nanospheres was successfully synthesized via hydrothermal carbonization at 140 °C, followed by calcination using cobalt nitrate hexahydrate (Co(NO3)2·6H2O), hexamethylenetetramine (HMT), sucrose, and sodium citrate (Na3C6H5O7). The porous Co3O4 hollow nanospheres consisted of nanoparticles with high specific surface area of mesoporous structure, and could provide active reaction sites for OER and ORR. When used as lithium-air battery cathode catalyst, the Co3O4/Super P (SP) electrode exhibited excellent cycle performance, resulting in high capacity and long life of lithium-air batteries.

Syntheses And Electrochemical Performances Of Li4Ti5O12 Anode Materials For Lithium Ion Battery, Yong-Long Zhang, Xue-Bu Hu, Yao-Qiong Wang, Dong-Hai Huang

Journal of Electrochemistry

Series of spinel lithium titanate (Li₄Ti₅O₁₂) materials were synthesized by one-step solid-state reaction using lithium acetate and TiO₂ as raw materials under different temperatures (750/800/850 °C) and atmospheres (N₂/air). The as-prepared Li₄Ti₅O₁₂ materials were investigated by thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, cyclic voltammotry and charge-discharge test to analyze their crystal structures, microstructures and electrochemical performances. The results show that the Li₄Ti₅O₁₂（L-800N）material obtained at 800 °C under nitrogen atmosphere exhibited better electrochemical performance and smaller particle size. The initial …

Flavour Chemicals In Electronic Cigarette Fluids, Peyton A. Tierney, Clarissa D. Karpinski, Jessica E. Brown, Wentai Luo, James F. Pankow

Chemistry Faculty Publications and Presentations

Background: Most e-cigarette liquids contain flavour chemicals. Flavour chemicals certified as safe for ingestion by the Flavor Extracts Manufacturers Association may not be safe for use in e-cigarettes. This study identified and measured flavour chemicals in 30 e-cigarette fluids.

Methods: Two brands of single-use e-cigarettes were selected and their fluids in multiple flavour types analysed by gas chromatography/mass spectrometry. For the same flavour types, and for selected confectionary flavours (eg, bubble gum and cotton candy), also analysed were convenience samples of e-cigarette fluids in refill bottles from local ‘vape’ shops and online retailers.

Results: In many liquids, total flavour chemicals …

Effect Of Maleic Acid On The Selectivity Of Glucose And Fructose Dehydration And Degradation, Ximing Zhang

Open Access Dissertations

5-Hydroxymethyfurfural (HMF), a platform chemical can upgrade to a variety of fuels and polymers, can be manufactured from lignocellulose. This study focuses on the Lewis and Brønsted acid effect on hexose dehydration for HMF production. We report the positive effect of maleic acid, a dicarboxylic acid used as Brønsted acid, on the selectivity of hexose dehydration to 5-hydroxymethyfurfural (HMF), and subsequent hydrolysis to levulinic and formic acids. We also describe the kinetic analysis of a Lewis acid (AlCl ₃) alone and in combination with HCl or maleic acid to catalyze the isomerization of glucose to fructose, dehydration of fructose …

Electrochemical Monitoring Of Cell Wall-Regulated Transient Extracellular Oxidative Burst From Single Plant Cells, Jun-Tao Liu, Yan-Ling Liu, Zhi Cheng, Shi-Jing Chen, Wei-Hua Huang

Journal of Electrochemistry

Oxidative burst by rapid, transient generation of reactive oxygen species (ROS) is a fundamental process for plant disease defense and signal transduction. ROS can be protective or toxic depending on their concentrations, and critical balance between ROS production and scavenging is regulated by complex and perfect mechanisms in plant cells. However, the process of rapid and transient ROS burst from plant cells and their regulatory mechanisms are far from being completely understood, owing to the methodological obstacles in real-time monitoring such a fast process. In this work, we showed the application of microelectrode electrochemistry with high spatiotemporal resolution to monitor …

Naio4 Oxidation Of Mussel Adhesive Protein Film And Its Corrosion Protection For Mg-1.0ca Alloy, Rui-Qing Hou, Ping-Li Jiang, Shi-Gang Dong, Chang-Jian Lin

Journal of Electrochemistry

The effect of oxidation of mussel adhesive protein (Mefp-1) film on the corrosive resistance for Mg-1.0Ca alloy was investigated by scanning electron microscopy (SEM), atom force microscopy (AFM), electron probe microanalysis (EPMA), Infrared reflection absorption spectroscopy (IRAS) and electrochemical methods. The results showed that the NaIO₄ induced oxidation of the pre-formed Mefp-1 film with porous morphology involved structural change of the DOPA group in the protein and resulted in a more uniform film with net-like morphology. The protein film without oxidation had an increasing resistance for the corrosion of Mg-1.0Ca alloy up to 7 days exposure. After oxidation, Epit …