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Articles 1 - 30 of 109

Full-Text Articles in Nanoscience and Nanotechnology

Electrocatalysts With High Activity And Stability For Polymer Electrolyte Membrane Fuel Cells, Zhongxin Song Sep 2018

Electrocatalysts With High Activity And Stability For Polymer Electrolyte Membrane Fuel Cells, Zhongxin Song

Electronic Thesis and Dissertation Repository

In addressing the activity and durability challenges facing electrocatalysts in polymer electrolyte membrane fuel cells (PEMFCs), atomic layer deposition (ALD) is emerging as a powerful technique for deposition of noble metals and transition metal oxides due to its exclusive advantages over other methods. The primary advantages of ALD are derived from the sequential, self-saturating, gas-surface reactions, and angstrom level control that take place during the deposition process. Therefore, ALD possesses the advantage in precisely control the particle size and uniform distribution on the substrate. By forming chemical bonds between the initial layer of ALD precursor and support atoms during the ...


Surface Area And Electrocatalytic Properties Of Feni Nanoparticles For The Oxygen Evolution Reaction (Oer), James Burrow May 2018

Surface Area And Electrocatalytic Properties Of Feni Nanoparticles For The Oxygen Evolution Reaction (Oer), James Burrow

Chemical Engineering Undergraduate Honors Theses

Iron-nickel bimetallic electrocatalysts have recently emerged as some of the best candidates for the oxygen evolution reaction (OER) in alkaline electrolyte. Understanding the effects of composition and morphology of iron-nickel nanoparticles is crucial for optimization and enhanced electrocatalyst performance. Both physical surface area and electrochemical surface area (ECSA) are functions of morphology. In this study, four different iron-nickel nanoparticle catalysts were synthesized. The catalysts were varied based on morphology (alloy versus core-shell) and composition (low, medium, and high stabilizer concentration). Brunauer-Emmett-Teller (BET) surface area analysis was conducted on three of the synthesized iron-nickel nanoparticles using a physisorption analyzer while electrochemical ...


Degradation Of Orange G Through Persulfate Activated Nanoscale Zerovalent Iron Composites And Boron-Doped Diamond Electrodes, Suzana Ivandic May 2018

Degradation Of Orange G Through Persulfate Activated Nanoscale Zerovalent Iron Composites And Boron-Doped Diamond Electrodes, Suzana Ivandic

Chemical Engineering Undergraduate Honors Theses

Properly treated wastewater is necessary for water reuse and to avoid unnecessary impacts on the environment. The poultry industry utilizes large amounts of water for poultry processing. The need for innovative ways to treat organic contaminants in the poultry wastewater industry is especially necessary due to increased poultry consumption. The U.S. Department of Agriculture projected Americans would consume approximately 92 pounds of chicken per person in 2017.1 Dissolved air flotation (DAF) is currently used in poultry wastewater treatment, but DAF does not remove organic contaminants efficiently per effluent standards. Implementation of processes that degrade contaminants directly would benefit ...


Spectro-Electrochemical Platforms For Dynamic Analyses Of Catalytic Cascade Systems, Nalin I. Andersen Apr 2018

Spectro-Electrochemical Platforms For Dynamic Analyses Of Catalytic Cascade Systems, Nalin I. Andersen

Nanoscience and Microsystems ETDs

The development of spectro-electrochemical platforms that facilitate the dynamic analyses of complex catalytic cascade systems was explored in this research. These systems facilitated multiple modalities of catalysts and were used as platforms for monitoring catalytic transformations quasi-in situ. The analytical platforms allowed for the characterization of intermediates and products using surface-enhanced Raman spectroscopy (SERS). The design and fabrication of these devices proved to be reproducible, made of materials that can be manipulated for multiple applications, and incorporate fluid mechanics, electrochemistry, and multimodal catalysis. Microfluidic technology offers capabilities for understanding catalytic cascade systems by providing precise dynamic control of complex ...


Graphene As A Solid-State Ligand For Palladium Catalyzed Cross-Coupling Reactions, Yuan Yang Jan 2018

Graphene As A Solid-State Ligand For Palladium Catalyzed Cross-Coupling Reactions, Yuan Yang

Theses and Dissertations

Palladium-catalyzed carbon-carbon cross-coupling reactions have emerged a broadly useful, selective and widely applicable method to synthesize pharmaceutical active ingredients. As currently practiced in the pharmaceutical industry, homogeneous Pd catalysts are typically used in cross-coupling reactions. The rational development of heterogeneous catalysts for cross-coupling reactions is critical for overcoming the major drawbacks of homogeneous catalysis including difficulties in the separation, purification, and quality control process in drug production. In order to apply heterogeneous catalysis to flow reactors that may overcome this limitation, the catalyst must be strongly bound to a support, highly stable with respect to leaching, and highly active. While ...


Surface And Structural Modification Of Carbon Electrodes For Electroanalysis And Electrochemical Conversion, Yan Zhang Jan 2018

Surface And Structural Modification Of Carbon Electrodes For Electroanalysis And Electrochemical Conversion, Yan Zhang

Theses and Dissertations--Chemistry

Electrocatalysis is key to both sensitive electrochemical sensing and efficient electrochemical energy conversion. Despite high catalytic activity, traditional metal catalysts have poor stability, low selectivity, and high cost. Metal-free, carbon-based materials are emerging as alternatives to metal-based catalysts because of their attractive features including natural abundance, environmental friendliness, high electrical conductivity, and large surface area. Altering surface functionalities and heteroatom doping are effective ways to promote catalytic performance of carbon-based catalysts. The first chapter of this dissertation focuses on developing electrode modification methods for electrochemical sensing of biomolecules. After electrochemical pretreatment, glassy carbon demonstrates impressive figures-of-merit in detecting small, redox-active ...


The Role Of Microenvironment Reagent Solubility On Reaction Kinetics Of 4-Nitrophenol Reduction, Michael P. Zeevi, Andrew Harrison, Christina Tang Jan 2018

The Role Of Microenvironment Reagent Solubility On Reaction Kinetics Of 4-Nitrophenol Reduction, Michael P. Zeevi, Andrew Harrison, Christina Tang

Undergraduate Research Posters

The Role of Microenvironment Reagent Solubility on Reaction Kinetics of 4-Nitrophenol Reduction

Michael Zeevi1 with Andrew Harrison1 and Christina Tang, PhD1

1Department of Chemical and Life Science Engineering, VCU School of Engineering

Introduction: Nanoparticles are of increasing interest due to their high surface area to volume ratio, as well as that they enable fine-tuning of the reaction microenvironment. Through flash nanoprecipitation, core-shell polymer nanoreactors were formed by directed self-assembly. Using the reduction of 4-nitrophenol as a model reduction reaction, we investigated the effect of reagent solubility in the nanoreactor microenvironment’s on nanoreactor kinetics.

Methods: The ...


Fabrication And Modification Of Titania Nanotube Arrays For Harvesting Solar Energy And Drug Delivery Applications, Ahmed El Ruby Abdel Rahman Mohamed Dec 2017

Fabrication And Modification Of Titania Nanotube Arrays For Harvesting Solar Energy And Drug Delivery Applications, Ahmed El Ruby Abdel Rahman Mohamed

Electronic Thesis and Dissertation Repository

The fast diminishing of fossil fuels in the near future, as well as the global warming caused by increasing greenhouse gases have motivated the urgent quest to develop advanced materials as cost-effective photoanodes for solar light harvesting and many other photocatalytic applications. Recently, titania nanotube arrays (TNTAs) fabricated by anodization process has attracted great interest due to their excellent properties such as: high surface area, vertically oriented, highly organized, one-dimensional, nanotubular structure, photoactivity, chemical stability and biocompatibility. This unique combination of excellent properties makes TNTAs an excellent photoanode for solar light harvesting. However, the relatively wide band gap energy of ...


Synergistic Interactions Of H2 And N2 With Molten Gallium In The Presence Of Plasma, Maria L. Carreon, Daniel F. Jaramillo-Cabanzo, Indira Chaudhuri, Madhu Menon, Mahendra K. Sunkara Dec 2017

Synergistic Interactions Of H2 And N2 With Molten Gallium In The Presence Of Plasma, Maria L. Carreon, Daniel F. Jaramillo-Cabanzo, Indira Chaudhuri, Madhu Menon, Mahendra K. Sunkara

Physics and Astronomy Faculty Publications

The present study examines the interaction of hydrogen and nitrogen plasmas with gallium in an effort to gain insights into the mechanisms behind the synergetic effect of plasma and a catalytic metal. Absorption/desorption experiments were performed, accompanied by theoretical-computational calculations. Experiments were carried out in a plasma-enhanced, Ga-packed, batch reactor and entailed monitoring the change in pressure at different temperatures. The results indicated a rapid adsorption/dissolution of the gas into the molten metal when gallium was exposed to plasma, even at a low temperature of 100 °C. The experimental observations, when hydrogen was used, indicate that gallium acts ...


Multiscale Modeling For Host-Guest Chemistry Of Dendrimers In Solution, Seung Ha Kim, Monica H. Lamm Oct 2017

Multiscale Modeling For Host-Guest Chemistry Of Dendrimers In Solution, Seung Ha Kim, Monica H. Lamm

Monica H. Lamm

Dendrimers have been widely used as nanostructured carriers for guest species in a variety of applications in medicine, catalysis, and environmental remediation. Theory and simulation methods are an important complement to experimental approaches that are designed to develop a fundamental understanding about how dendrimers interact with guest molecules. This review focuses on computational studies aimed at providing a better understanding of the relevant physicochemical parameters at play in the binding and release mechanisms between polyamidoamine (PAMAM) dendrimers and guest species. We highlight recent contributions that model supramolecular dendrimer-guest complexes over the temporal and spatial scales spanned by simulation methods ranging ...


Interfacial Charge Distributions In Carbon-Supported Palladium Catalysts, Radhika Rao, Raoul Blume, Thomas W. Hansen, Erika Fuentes, Kathleen Dreyer, Simona Moldovan, Ovidiu Ersen, David D. Hibbitts, Yves J. Chabal, Robert Schlögl, Jean-Philippe Tessonnier Aug 2017

Interfacial Charge Distributions In Carbon-Supported Palladium Catalysts, Radhika Rao, Raoul Blume, Thomas W. Hansen, Erika Fuentes, Kathleen Dreyer, Simona Moldovan, Ovidiu Ersen, David D. Hibbitts, Yves J. Chabal, Robert Schlögl, Jean-Philippe Tessonnier

Chemical and Biological Engineering Publications

Controlling the charge transfer between a semiconducting catalyst carrier and the supported transition metal active phase represents an elite strategy for fine turning the electronic structure of the catalytic centers, hence their activity and selectivity. These phenomena have been theoretically and experimentally elucidated for oxide supports but remain poorly understood for carbons due to their complex nanoscale structure. Here, we combine advanced spectroscopy and microscopy on model Pd/C samples to decouple the electronic and surface chemistry effects on catalytic performance. Our investigations reveal trends between the charge distribution at the palladium–carbon interface and the metal’s selectivity for ...


Ion Size Effects On The Properties Of Charge Regulating Electric Double Layers, Divya Jyoti Prakash Jul 2017

Ion Size Effects On The Properties Of Charge Regulating Electric Double Layers, Divya Jyoti Prakash

Nanoscience and Microsystems ETDs

The behavior of charged interfaces formed in various systems like colloidal solution, fuel cells, battery, electro-deposition, catalysis is governed by the properties of electrical double layer(EDL). Civilized model with charge regulation boundary condition determined by thermodynamic equilibrium at the interface has been used to model electrical double layer and shows that size of the solvent plays a critical role in characterizing the properties of EDL using classical density functional theory.This thesis investigates the impact of ion size in electrolyte solutions on the electrical double layer formed at the interface using a similar model. It is found that ion ...


Graphite And Graphene-Oxide Based Pgm-Free Model Catalysts For The Oxygen Reduction Reaction, Joseph Henry Dumont Jul 2017

Graphite And Graphene-Oxide Based Pgm-Free Model Catalysts For The Oxygen Reduction Reaction, Joseph Henry Dumont

Nanoscience and Microsystems ETDs

The world currently relies heavily on fossil fuels such as coal, oil, and natural gas for its energy. Fossil fuels are non-renewable, that is, they draw on finite resources that will eventually dwindle, becoming too expensive or too environmentally damaging to retrieve. One alternative source of energy are fuel cells, electrochemical devices that convert chemical energy to cleanly and efficiently produce electricity. They can be used in a wide range of applications, including transportation, stationary, portable and emergency power sources. Their development has been slowed by the high cost of PGM electrocatalysts needed at both electrodes as well as sluggish ...


A Study Of Iron-Nitrogen-Carbon Fuel Cell Catalysts: Chemistry – Nanostructure – Performance, Michael J. Workman Mar 2017

A Study Of Iron-Nitrogen-Carbon Fuel Cell Catalysts: Chemistry – Nanostructure – Performance, Michael J. Workman

Nanoscience and Microsystems ETDs

Fuel cells have the potential to be a pollution-free, low-cost, and energy efficient alternative to the internal combustion engine for transportation and small-scale stationary power applications. The current state of fuel cell technology has already achieved two of these three lofty goals. The remaining barrier to wide-scale deployment is the high cost, which is primarily caused by dependence on large amounts of platinum to catalyze the energy conversion reactions. To overcome this barrier and facilitate the integration of fuel cells into mainstream applications, research into a new class of catalyst materials that do not require platinum is needed.

There has ...


Tunable Nanocomposite Membranes For Water Remediation And Separations, Sebastián Hernández Sierra Jan 2017

Tunable Nanocomposite Membranes For Water Remediation And Separations, Sebastián Hernández Sierra

Theses and Dissertations--Chemical and Materials Engineering

Nano-structured material fabrication using functionalized membranes with polyelectrolytes is a promising research field for water pollution, catalytic and mining applications. These responsive polymers react to external stimuli like temperature, pH, radiation, ionic strength or chemical composition. Such nanomaterials provide novel hybrid properties and can also be self-supported in addition to the membranes.

Polyelectrolytes (as hydrogels) have pH responsiveness. The hydrogel moieties gain or lose protons based on the pH, displaying swelling properties. These responsive materials can be exploited to synthesize metal nanoparticles in situ using their functional groups, or to immobilize other polyelectrolytes and biomolecules. Due to their properties, these ...


Characterization Of Molecular Communication Based On Cell Metabolism Through Mutual Information And Flux Balance Analysis, Zahmeeth Sayed Sakkaff Dec 2016

Characterization Of Molecular Communication Based On Cell Metabolism Through Mutual Information And Flux Balance Analysis, Zahmeeth Sayed Sakkaff

Computer Science and Engineering: Theses, Dissertations, and Student Research

Synthetic biology is providing novel tools to engineer cells and access the basis of their molecular information processing, including their communication channels based on chemical reactions and molecule exchange. Molecular communication is a discipline in communication engineering that studies these types of communications and ways to exploit them for novel purposes, such as the development of ubiquitous and heterogeneous communication networks to interconnect biological cells with nano and biotechnology-enabled devices, i.e., the Internet of Bio-Nano Things. One major problem in realizing these goals stands in the development of reliable techniques to control the engineered cells and their behavior from ...


Metal Assisted Chemical Etching, Inayat Bajwa May 2016

Metal Assisted Chemical Etching, Inayat Bajwa

Protocols and Reports

No abstract provided.


Doped Tio2 Nanowires For Applications In Dye Sensitized Solar Cells And Sacrifical Hydrogen Production, Qasem Alsharari Apr 2016

Doped Tio2 Nanowires For Applications In Dye Sensitized Solar Cells And Sacrifical Hydrogen Production, Qasem Alsharari

Electronic Thesis and Dissertation Repository

This thesis explores the synthesis of metal oxide 1-D nanowires using a sol-gel method in supercritical carbon dioxide (sc-CO2), as an environmental friendly enabling solvent. Porous nanowires were synthesized and their performance was tested in dye sensitized solar cell and sacrifical hydrogen production. Titanium isopropoxide (TIP) was used as a precursor for titania synthesis while copper, bismuth and indium were examined as dopants, respectively. The sol-gel reactions were catalyzed by acetic acid in CO2 at a temperature of 60 °C and pressure of 5000 psi. It was observed that acetic acid/monomer ratio > 4 produced nanowires while a ...


Characterizing Graphitic Carbon With X-Ray Photoelectron Spectroscopy: A Step-By-Step Approach, Raoul Blume, Dirk Rosenthal, Jean-Philippe Tessonnier, Henan Li, Axel Knop-Gericke, Robert Schlögl Sep 2015

Characterizing Graphitic Carbon With X-Ray Photoelectron Spectroscopy: A Step-By-Step Approach, Raoul Blume, Dirk Rosenthal, Jean-Philippe Tessonnier, Henan Li, Axel Knop-Gericke, Robert Schlögl

Chemical and Biological Engineering Publications

X-ray photoelectron spectroscopy (XPS) is a widely used technique for characterizing the chemical and electronic properties of highly ordered carbon nanostructures, such as carbon nanotubes and graphene. However, the analysis of XPS data—in particular the C 1s region—can be complex, impeding a straightforward evaluation of the data. In this work, an overview of extrinsic and intrinsic effects that influence the C 1s XPS spectra—for example, photon broadening or carbon–catalyst interaction—of various graphitic samples is presented. Controlled manipulation of such samples is performed by annealing, sputtering, and oxygen functionalization to identify different C[BOND]C bonding ...


Nanonickel Catalyst Reinforced With Silicate For Methane Decomposition To Produce Hydrogen And Nanocarbon: Synthesis By Co-Precipitation Cum Modified Stöber Method, Upm Ashik, Wma Wan Daud May 2015

Nanonickel Catalyst Reinforced With Silicate For Methane Decomposition To Produce Hydrogen And Nanocarbon: Synthesis By Co-Precipitation Cum Modified Stöber Method, Upm Ashik, Wma Wan Daud

upm ashik

Co-precipitation cum modified Stöber method is a continuous process avoiding application of higher temperature treatment before supporting nanometal with SiO2, irrespective of pre-preparation methods. We have conducted the co-precipitation process without undertaking calcination under air in order to avoid even a partial particle agglomeration and hence maintained average particle size [similar]30 nm after enforcing with SiO2. This is the first report adopting such an unceasing preparation for preparing metal/silicate nanostructures. Furthermore, n-Ni/SiO2 nanostructured catalysts were used for thermocatalytic decomposition of methane to produce hydrogen and carbon nanotubes. The catalyst was found to be very stable and the ...


Designed Synthesis Of Nanoporous Organic Polymers For Selective Gas Uptake And Catalytic Applications, Pezhman Arab Jan 2015

Designed Synthesis Of Nanoporous Organic Polymers For Selective Gas Uptake And Catalytic Applications, Pezhman Arab

Theses and Dissertations

Design and synthesis of porous organic polymers have attracted considerable attentions during the past decade due to their wide range of applications in gas storage, gas separation, energy conversion, and catalysis. Porous organic polymers can be pre-synthetically and post-synthetically functionalized with a wide variety of functionalities for desirable applications. Along these pursuits, we introduced new synthetic strategies for preparation of porous organic polymers for selective CO2 capture.

Porous azo-linked polymers (ALPs) were synthesized by an oxidative reaction of amine-based monomers using copper(I) as a catalyst which leads to azo-linkage formation. ALPs exhibit high surface areas of up to ...


Gas Sensing Properties And P-Type Response Of Ald Tio2 Coated Carbon Nanotubes, Catherine Marichy, Nicola Donato, Mariangela Latino, Marc Georg Willinger, Jean-Philippe Tessonnier, Giovanni Neri, Nicola Pinna Jan 2015

Gas Sensing Properties And P-Type Response Of Ald Tio2 Coated Carbon Nanotubes, Catherine Marichy, Nicola Donato, Mariangela Latino, Marc Georg Willinger, Jean-Philippe Tessonnier, Giovanni Neri, Nicola Pinna

Chemical and Biological Engineering Publications

Amorphous titanium dioxide-coated carbon nanotubes (CNTs) were prepared by atomic layer deposition (ALD) and investigated as sensing layers for resistive NO2 and O2 gas sensors. By varying ALD process conditions and CNT structure, heterostructures with different metal oxide grain size, morphology and coating thickness were synthesized. Higher responses were observed with homogeneous and continuous 5.5 nm thick films onto CNTs at an operating temperature of 150 °C, while CNTs decorated with either discontinuous film or TiO2 nanoparticles showed a weak response close to the one of device made of bare CNTs. An unexpected p-type behavior in presence of the ...


Au@Tio2 Nanocomposites For The Catalytic Degradation Of Methyl Orange And Methylene Blue: An Electron Relay Effect, Mohammad Mansoob Khan Dr, J. Lee, M. H. Cho Aug 2014

Au@Tio2 Nanocomposites For The Catalytic Degradation Of Methyl Orange And Methylene Blue: An Electron Relay Effect, Mohammad Mansoob Khan Dr, J. Lee, M. H. Cho

Dr. Mohammad Mansoob Khan

Au@TiO2 nanocomposites were used for the catalytic degradation of methyl orange and methylene blue by NaBH4. A detail pathway for step by step reduction, oxidation and complete mineralization of intermediates into the respective end-products was established by UV-vis spectroscopy, chemical oxygen demand, ion chromatography and cyclic voltammetry (CV). CV studies confirmed that the dyes were reduced and oxidized to the end-products by NaBH4 in the presence of Au@TiO2 nanocomposites and O2•, •OH and HO2• radicals generated in-situ. Results suggest that Au@TiO2 nanocomposites not only assist in the decolorization of dyes, but also promote their complete mineralization into ...


Highly Visible Light Active Ag@Zno Nanocomposites Synthesized By Gel-Combustion Route, Mohammad Mansoob Khan Dr, S. A. Ansari, J. Lee, M. H. Cho Aug 2014

Highly Visible Light Active Ag@Zno Nanocomposites Synthesized By Gel-Combustion Route, Mohammad Mansoob Khan Dr, S. A. Ansari, J. Lee, M. H. Cho

Dr. Mohammad Mansoob Khan

Highly visible light active 1% and 3% Ag@ZnO nanocomposites were synthesized via a gel combustion route using citric acid as a fuel. The formation of the nanocomposites with enhanced properties was confirmed using a range of characterization techniques, photocatalysis and photoelectrochemical studies. Compared to the pristine ZnO nanoparticles, the Ag@ZnO nanocomposites exhibited enhanced visible light photocatalytic activity for the degradation of methylene blue and photoelectrochemical response. A mechanism was proposed to account for the photocatalytic activities of the Ag@ZnO nanocomposite that showed the surface plasmon resonance (SPR) of Ag is an effective way of enhancing the visible ...


Functional Carbons And Carbon Nanohybrids For The Catalytic Conversion Of Biomass To Renewable Chemicals In The Condensed Phase, John Matthiesen, Thomas Hoff, Chi Liu, Charles Pueschel, Radhika Rao, Jean-Philippe Tessonnier Jun 2014

Functional Carbons And Carbon Nanohybrids For The Catalytic Conversion Of Biomass To Renewable Chemicals In The Condensed Phase, John Matthiesen, Thomas Hoff, Chi Liu, Charles Pueschel, Radhika Rao, Jean-Philippe Tessonnier

Chemical and Biological Engineering Publications

The production of chemicals from lignocellulosic biomass provides opportunities to synthesize chemicals with new functionalities and grow a more sustainable chemical industry. However, new challenges emerge as research transitions from petrochemistry to biorenewable chemistry. Compared to petrochemisty, the selective conversion of biomass-derived carbohydrates requires most catalytic reactions to take place at low temperatures (< 300 °C) and in the condensed phase to prevent reactants and products from degrading. The stability of heterogeneous catalysts in liquid water above the normal boiling point represents one of the major challenges to overcome. Herein, we review some of the latest advances in the field with an emphasis on the role of carbon materials and carbon nanohybrids in addressing this challenge.


Highly Photoactive Sno2 Nanostructures Engineered By Electrochemically Active Biofilm, S. A. Ansari, Mohammad Mansoob Khan Dr, M. O. Ansari, J. Lee, M. H. Cho Feb 2014

Highly Photoactive Sno2 Nanostructures Engineered By Electrochemically Active Biofilm, S. A. Ansari, Mohammad Mansoob Khan Dr, M. O. Ansari, J. Lee, M. H. Cho

Dr. Mohammad Mansoob Khan

This paper reports the defect-induced band gap narrowing of pure SnO2 nanostructures (p-SnO2) using an electrochemically active biofilm (EAB). The proposed approach is biogenic, simple and green. Systematic characterization of the modified SnO2 nanostructures (m-SnO2) revealed EAB-mediated defects in pure SnO2 nanostructures (p-SnO2). m-SnO2 nanostructures in visible light showed the enhanced photocatalytic degradation of p-nitrophenol and methylene blue compared to p-SnO2 nanostructures. Photoelectrochemical studies, such as electrochemical impedance spectroscopy and linear scan voltammetry, also revealed a significant increase in the visible light response of m-SnO2 compared to p-SnO2 nanostructures. The enhanced activities of m-SnO2 in visible light was attributed to ...


Band Gap Engineered Tio2 Nanoparticles For Visible Light Induced Photoelectrochemical And Photocatalytic Studies, Mohammad Mansoob Khan Dr, S A. Ansari, D Pradhan, D H. Han, J Lee, M. H. Cho Dec 2013

Band Gap Engineered Tio2 Nanoparticles For Visible Light Induced Photoelectrochemical And Photocatalytic Studies, Mohammad Mansoob Khan Dr, S A. Ansari, D Pradhan, D H. Han, J Lee, M. H. Cho

Dr. Mohammad Mansoob Khan

Visible light-active TiO2 (m-TiO2) nanoparticles were obtained by an electron beam treatment of commercial TiO2 (p-TiO2) nanoparticles. The m-TiO2 nanoparticles exhibited a distinct red-shift in the UV-visible absorption spectrum and a much narrower band gap (2.85 eV) due to defects as confirmed by diffuse reflectance spectroscopy (DRS), photoluminescence (PL), X-ray diffraction, Raman spectroscopy, electron paramagnetic resonance, transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS) and linear scan voltammetry (LSV). The XPS revealed changes in the surface states, composition, Ti4+ to Ti3+ ratio, and oxygen deficiencies in the m-TiO2. The valence band XPS, DRS and PL results ...


Structure And Energetics Of Nanoparticles And Ionomer Films In Fuel Cell Catalyst Layers, Qianping He Dec 2013

Structure And Energetics Of Nanoparticles And Ionomer Films In Fuel Cell Catalyst Layers, Qianping He

Doctoral Dissertations

Improving the durability and utilization efficiency of the platinum-on-carbon (Pt/C) catalyst is of vital importance to the commercialization of the polymer electrolyte membrane fuel cell (PEMFC). This body of work provides molecular level insights to aid the fulfillment of this goal. Chapter 1 describes the use of molecular dynamics (MD) simulation in an effort to understand the Pt/C degradation issue from the nano-adhesion point of view. The roles of catalyst nanoparticle size, shape, Pt/C surface oxidation and the extent of ionomer film hydration are investigated to study their effects on nano-particle adhesion. It is found that the ...


Optimization Of Gold Nanoparticles Synthesis By Stainless Steel For H2o2 And Glucose Detection, T. H. Han, Mohammad Mansoob Khan Dr, J. Lee, M. H. Cho Sep 2013

Optimization Of Gold Nanoparticles Synthesis By Stainless Steel For H2o2 And Glucose Detection, T. H. Han, Mohammad Mansoob Khan Dr, J. Lee, M. H. Cho

Dr. Mohammad Mansoob Khan

The synthesis of (+)AuNPs procedure using a stainless-steel mesh was optimized. The optimal synthetic parameters were found to be one piece of stainless-steel mesh (22.5 cm2 in surface area) in 100 mL of a 1 mM precursor, precursor solution pH 4, and reaction temperature of 30°C. Under the optimal conditions, the as-synthesized (+)AuNPs were highly positively charged (+24.2 mV). Therefore, the as-synthesized (+)AuNPs act as a peroxidase mimic and provide a simple, fast, highly sensitive and selective colorimetric method for H2O2 detection with a detection limit of 0.06 mM in the linear range from 0.06 ...


Novel Ag@Tio2 Nanocomposite Synthesized By Electrochemically Active Biofilm For Nonenzymatic Hydrogen Peroxide Sensor, Mohammad Mansoob Khan Dr, S. A. Ansari, J. Lee, M. H. Cho Jul 2013

Novel Ag@Tio2 Nanocomposite Synthesized By Electrochemically Active Biofilm For Nonenzymatic Hydrogen Peroxide Sensor, Mohammad Mansoob Khan Dr, S. A. Ansari, J. Lee, M. H. Cho

Dr. Mohammad Mansoob Khan

A novel nonenzymatic sensor for H2O2 was developed based on an Ag@TiO2 nanocomposite synthesized using a simple and cost effective approach with an electrochemically active biofilm. The optical, structural, morphological and electrochemical properties of the as-prepared Ag@TiO2 nanocomposite were examined by UV-vis spectroscopy, x-ray diffraction, transmission electron microscopy and cyclic voltammetry (CV). The Ag@TiO2 nanocomposite was fabricated on a glassy carbon electrode (GCE) and their electrochemical performance was analyzed by CV, differential pulse voltammetry and electrochemical impedance spectroscopy. The Ag@TiO2 nanocomposite modified GCE (Ag@TiO2/GCE) displayed excellent performance towards H2O2 sensing at −0.73 V ...