Electrospun Nanofiber Metal Oxides for Reactive Sorption and Catalysis

Electrospun Nanofiber Metal Oxides for Reactive Sorption and Catalysis
Author: Faisal Alshafei
Publisher:
Total Pages: 209
Release: 2018
Genre:
ISBN:

Electrospun metal oxides is a new class of materials that have demonstrated auspicious potential and have been used in a wide range of applications. In this work, various smooth, continuous, and defect-controlled metal-polymer nanofibers were synthesized via electrospinning with diameters ranging from approximately 50 to 600 nm, and subsequently thermally treated to decompose the polymer (PVP or PEO) and form highly porous, fibrous metal (Cu-, Ni-, Mg-, and Ca-) oxide nanostructures. In the first part of this thesis, parameters that influence the electrospinning process were systematically investigated for PVP-Cu(NO3)2 systems. Both solution properties (polymer/metal concentration, polymer molecular weight, and solvent identity) and processing conditions (applied voltage, tip-of-needle to collector distance, extrusion rate, and humidity) were varied to probe the effect of these electrospinning factors on fiber quality prior to thermal treatment. The data collected demonstrated that factors that do not directly and strongly influence viscosity, conductivity and solvent evaporation (e.g., applied voltage, extrusion rate, and tip-of-needle to collecting plate distance) do not have substantial effects on fiber diameter and morphology. Subsequent thermal treatment of the electrospun nanofibers and choice of metal, however, were found to markedly impact the morphology of the formed fiber oxides (e.g., string-like structures or segmented particles). In the second part of this thesis, electrospun fiber metal oxide materials were tested in two main applications (high temperature CO2 removal and low-temperature H2S removal) and their performance was compared to materials prepared via traditional synthesis routes (e.g., sol-gel, co-precipitation, hydrothermal treatment, etc.) In the first application, CaO-based materials were tested as potential sorbents in sorption enhanced steam methane reforming (SE-SMR) to capture CO2 and shift the reaction towards producing more hydrogen. The electrospun CaO-nanofibers, when reacted with CO2, achieved complete conversion to CaCO3 and had an initial CO2 sorption capacity of 0.79gCO2/gsorbent at 873 K and 923 K (highest of all materials tested), as the macro-porosity imparted by the electrospinning process improved the CO2 diffusion through the CaCO3 product layers. Furthermore, when these electrospun sorbents were added to a commercial catalyst and tested in SE-SMR conditions, they had three to four times longer breakthrough times than CaO sorbents derived from natural sources (e.g., CaO-marble). To further improve the stability of CaO-based sorbents, chemical doping of Ca-supports with Mg, Al, Y, La, Zn, Er, Ga, Li, Nd, In, and Co was combined with electrospinning to yield mixed oxide materials with high sorption capacities (~0.4-0.7 gCO2/gsorbent) and improved durability (up to 17 cycles). It was demonstrated that metals that have high Tammann temperatures were effective at reducing sintering and CaO particle agglomeration by acting as spacers, thus, retaining the sorbent's initial sorption capacity upon repeated cycling. In the second application, CuO nanofibers with varying diameters (~70-650 nm) were prepared from two polymers (PEO and PVP) and reacted with H2S at ambient conditions to form CuS. The results from this study demonstrated that the sulfur removal capacity of CuO materials, whether prepared via electrospinning, hydrothermal treatment, sol-gel or co-precipitation, was strongly dependent on crystallite size (a linear relationship was established between CuO removal capacity and crystallite size and held true for all CuO materials with crystallites between 5-26 nm) and CuO purity (i.e., presence of residual carbon on the surface of the oxide). Indeed, properties such as surface area, pore volume and morphology (e.g., flowerlike, fiber-like, belt-like, etc.) were found to have an insignificant impact on removal capacity. This work offers fundamental insights into the design of multifunctional and highly porous metal oxide nanofibers for sorptive and catalytic applications.

Metal Oxide-Based Nanofibers and Their Applications

Metal Oxide-Based Nanofibers and Their Applications
Author: Vincenzo Esposito
Publisher: Elsevier
Total Pages: 461
Release: 2021-10-25
Genre: Technology & Engineering
ISBN: 0128209070

Metal Oxide-based Nanofibers and their Applications provides an in-depth overview on developments surrounding the synthesis, characterization properties, and applications achieved by scientific leaders in the area. Sections deal with the theoretical and experimental aspects of the synthesis and methodologies to control microstructure, composition and shape of the nanofibrous metal oxides, review the applications of metal oxide nanofibers in diverse technologies, with special focus on the relation between the structural, morphological and compositional features of the nanofibers, cover applications of metal oxide nanofibers in the fields of sensing (biosensing, gas sensing), and consider biomedical and cleaning technologies. Lastly, a final section covers their application in energy generation and storage technologies (e. g. piezoelectric, solar cells, solid oxide fuel cells, lithium-ion batteries, supercapacitors, and hydrogen storage are reviewed. Reviews electrospinning methods for the synthesis and design of nanocomposites and hybrid metal oxide nanofibers Discusses applications of metal oxide nanofibers in sensing, biomedical fields, cleaning technologies, and energy Emphasizes the structural, morphological and compositional properties of nanofibers and their effect on device performance

Development of Chemically Active Metal Oxide Composite Nanofiber Filters for Water Treatment

Development of Chemically Active Metal Oxide Composite Nanofiber Filters for Water Treatment
Author: Katherine E. Greenstein
Publisher:
Total Pages: 189
Release: 2016
Genre: Electrospinning
ISBN:

In this study, we develop electrospun nanofiber filters that harness nano-scaled hematite (Fe2O3) for sorption of inorganic contaminants (e.g., As, Pb) and nano-scaled titanium dioxide (TiO2) for use with ultraviolet (UV) and visible light as an advanced oxidation process (AOP) for removal of emerging organic contaminants (e.g., benzotriazole, carbamazepine, DEET). Most importantly, we strive to optimize both reactivity and material strength to develop cohesive, durable filtration platforms that overcome barriers to use of nanomaterials in water treatment (e.g., concerns over leaching of nanoparticles deployed as suspensions). Herein, we first demonstrate reactivity optimization of pure (though brittle) TiO2 nanofiber photocatalysts by noble metal catalyst (Au) surface loading. Additionally, we optimize polymer-Fe2O3 composite nanofibers for reactivity while maintaining material flexibility by coating the doped polymer with additional Fe2O3 surfaces available for metal/metalloid uptake. Finally, we apply reactivity optimization and strategies to maintain material strength in the development of carbon/TiO2 nanofiber composites used for (photo)chemical filtration of water containing emerging organic contaminants. Ultimately, we find that nanofiber composites exhibit substantial reactivity and structural integrity in water treatment platforms. Outcomes of this work contribute to making nanomaterials, which have been studied for decades but have yet to be commercially employed for water treatment, practical for chemically active water filtration.

Metal Oxide Nanofiber Catalysis

Metal Oxide Nanofiber Catalysis
Author: Daniel Patrick Noon
Publisher:
Total Pages: 217
Release: 2015
Genre:
ISBN:

The synthesis of solids with finely turned nanostructures that offer superior catalytic performance is a major challenge in heterogeneous catalysis for gas phase reactions. Industrial catalysts are almost universally composed of quasi-spherical nanoparticles, or powders plagued with particle agglomeration, migration and sintering problems that lead to deactivation. In this work, quasi-cylindrical nanofibers are electrospun and extensively utilized for the oxidative coupling of methane (OCM), as well as for propylene epoxidation and the catalytic partial oxidation (CPO) of methane. Electrospun nanofibers of metal oxides may be tuned to have high surface areas but typically possess no internal porosity, reducing diffusion limitations that would lengthen the exposure of target intermediate oxidation products to unselective catalysis. Additionally, experiments and density functional theory (DFT) studies have previously shown that pentagonal Ag nanowires exhibit higher selectivity than conventional particles in ethylene epoxidation since their surfaces are terminated mainly by the (100) surface facet rather than the lowest energy (111) facet that dominates particles. Hence, nanofibers may elevate catalytic performance in broad range of partial oxidation reaction schemes. Research into the oxidative coupling of methane, or, the catalytic conversion of methane to ethane and ethylene by molecular oxygen, almost exclusively utilized powders and failed to result in viable catalyst despite four decades of intense, global efforts. Accordingly, the use of catalytic nanofibers provides a potentially fruitful path towards a solution. Here, nanofiber fabrics of La2O3-CeO2 were electrospun and used in fixed bed OCM reactors to achieve 70% selectivity and 16% yield for C2+ hydrocarbons at a CH4/O2 feed ratio of 7 and remarkably low feed temperature of 470 ?C. Powders of La2O3-CeO2 documented in the literature exhibit similar selectivity and yield, but with the feed at 715 ?C. The electrospun fabrics used in this research were found to have dense nanofibers of diameters typically within the 20 - 200 nm range and, accordingly, surface areas of 10 - 20 m2/g as well as thinner fibers tending towards both higher C2+ selectivity and CH4 conversion. While performing reaction engineering studies using the aforementioned fabrics, it was found that designing reactors comprising dual catalytic La2O3-CeO2 fabric beds with inter-stage O2 injection and cooling pushes yields to 21%. Moreover, a novel in-situ microprobe sampling technique for acquiring spatial temperature and concentration profiles within these OCM reactors was developed, providing a means to formulate and validate detailed chemical kinetic mechanisms. This has led to the discovery of prompt H2 formation in OCM, a feature previously unidentified that may break ground in mechanism refinement. Additionally, spatial concentration and temperature profiles were acquired in fixed bed reactors comprising La2O3-CeO2 fabrics doped with varying levels of Ir and fed CH4/O2 mixtures to gain insight into the transition from OCM to the catalytic partial oxidation of methane. It was found that, in general, OCM and CPO appear to occur both in parallel and sequentially in a fixed bed, evidenced by the temporary rise and subsequent destruction of C2+ hydrocarbons when the catalyst is doped with 0.05 wt% Ir. Clearly, this sampling technique has broad applicability in catalysis research over a limitless number of reactions for the acquisition of comprehensive data sets potentially useful for formulating and refining detailed chemical kinetic mechanisms (DCKM), thus furthering a fundamental understanding of the catalysis and advancing faster towards the development of higher performing materials.

Metal Oxide-Based Photocatalysis

Metal Oxide-Based Photocatalysis
Author: Adriana Zaleska-Medynska
Publisher: Elsevier
Total Pages: 372
Release: 2018-04-09
Genre: Technology & Engineering
ISBN: 0128116331

Metal Oxide-Based Photocatalysis: Fundamentals and Prospects for Application explains the principles and fundamentals of metal oxide-based photocatalysis and the requirements necessary for their use in photocatalysis. It also discusses preparation methods for photocatalysis, and the advantages, disadvantages and achievements of the most important metal oxides (TiO2, ZnO, Fe2O3, Ta2O3, CuO, NiO, Cr2O3, RuO2, etc.). The book concludes with the most important photocatalytic applications and an overview of the future. Applications are organized by potential needs and solutions, addressing such areas as water treatment, hydrogen production, air treatment, chemical synthesis, and applications in medicine and construction. Provides coverage of applications, presenting needs and solutions Covers essential applications, such as water treatment, hydrogen production, air depollution, medical applications, and much more Includes the characterization of the most important metal oxides used in heterogeneous photocatalysis

Metal Oxide Nanostructures from Electrospun Carbon Templates

Metal Oxide Nanostructures from Electrospun Carbon Templates
Author: Dickson Andala
Publisher: LAP Lambert Academic Publishing
Total Pages: 252
Release: 2012-03
Genre:
ISBN: 9783848434541

The work covered herein discusses for the first time various techniques used in the fabrication of metal oxide nanofibers and nanotubes from eletrospun carbon fibers as templates. The nanofibers were prepared by electrospinning metal oxide precursor inside a polymer matrix. The metal oxide tubes were by tubes by fiber templating. This was followed by calcination to yield the nanofibers and nanotubes. Their morphological, structural, optoelectronic and catalytic properties are also discussed. Among key applications they have found utilization as catalyst supports. Palladium nanoparticles have been supported on Titanium dioxide nanofibers and applied in Heck-coupling reactions. Similarly, included is the effect of impurities on the metal oxide tubes properties done by doping with metal ions. In addition, photocatalytic behavior of metal oxides nanofibers have also been discussed.

Design, Fabrication, and Characterization of Multifunctional Nanomaterials

Design, Fabrication, and Characterization of Multifunctional Nanomaterials
Author: Sabu Thomas
Publisher: Elsevier
Total Pages: 610
Release: 2021-11-24
Genre: Science
ISBN: 012820883X

Design, Fabrication, and Characterization of Multifunctional Nanomaterials covers major techniques for the design, synthesis, and development of multifunctional nanomaterials. The chapters highlight the main characterization techniques, including X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, and scanning probe microscopy.The book explores major synthesis methods and functional studies, including: Brillouin spectroscopy; Temperature-dependent Raman spectroscopic studies; Magnetic, ferroelectric, and magneto-electric coupling analysis; Organ-on-a-chip methods for testing nanomaterials; Magnetron sputtering techniques; Pulsed laser deposition techniques; Positron annihilation spectroscopy to prove defects in nanomaterials; Electroanalytic techniques. This is an important reference source for materials science students, scientists, and engineers who are looking to increase their understanding of design and fabrication techniques for a range of multifunctional nanomaterials. Explains the major design and fabrication techniques and processes for a range of multifunctional nanomaterials; Demonstrates the design and development of magnetic, ferroelectric, multiferroic, and carbon nanomaterials for electronic applications, energy generation, and storage; Green synthesis techniques and the development of nanofibers and thin films are also emphasized.

Nanofiber Research

Nanofiber Research
Author: Mohammed Rahman
Publisher: BoD – Books on Demand
Total Pages: 256
Release: 2016-10-19
Genre: Science
ISBN: 9535125281

This book titled Nanofiber Research - Reaching New Heights contains a number of latest research results on growth and developments on material fibers in nanoscale. It is a promising novel research area that has received a lot of interest in recent years. This book includes interesting reports on cutting-edge science and technology related to synthesis, morphology, control, self-assembly and prospective application of nanofibers. I hope that the book will lead to systematization of nanofiber science, creation of new nanofiber research field and further promotion of nanofiber technology. This potentially unique work offers various approaches on the implementation of nanofibers. As it is widely known, nanotechnology presents the control of matter at the nanoscale and nano-dimensions within few nanometers, whereas this exclusive phenomenon enables us to regulate and control novel applications with nanofibers. This book presents an overview of recent and current nanofibers fundamental, significant applications and implementation research worldwide. It examined the methods of nanofiber synthesis, types of fibers used and potential applications associated with nanofiber researches. It is an important booklet for research organizations, governmental research centers, academic libraries and R

Adsorption through Advanced Nanoscale Materials

Adsorption through Advanced Nanoscale Materials
Author: Chandrabhan Verma
Publisher: Elsevier
Total Pages: 729
Release: 2023-08-14
Genre: Technology & Engineering
ISBN: 0443184577

Adsorption through Advanced Nanoscale Materials: Applications in Environmental Remediation brings together the latest developments in the utilization of advanced nanoadsorbents in wastewater treatment, pollution control, removal and remediation, gas separation and other environmental applications. The book begins by providing an overview of absorption, adsorbents and nanoadsorbents, introducing properties, classification, synthesis, characterization, enhancement of adsorption capabilities, principles and advantages and disadvantages of nanoadsorbents. Other sections cover the preparation of advanced nanoadsorbents based on specific materials for wastewater treatment, including adsorbents incorporating carbon nanotubes, graphene and graphene oxide, carbon dots and fullerene, polymer nanocomposites, metal oxides, nanoclay, nanofillers, and filtration membranes. Final sections examine the role of nanoadsorbents in broader environmental applications, including areas such as pollution control and removal and gas separation. Finally, other important considerations are studied, including toxicity and health impact, ecotoxicological effects, commercialization and economic issues, challenges and research gaps, trends, and future opportunities. Provides in-depth coverage of nanoadsorbents for a range of targeted environmental applications Covers, in detail, fundamentals such as synthesis methods, characterization and inhibition mechanisms Addresses key areas such as toxicity, health impact, research gaps, trends and commercialization

Electrospun Nanofibers

Electrospun Nanofibers
Author: Mehdi Afshari
Publisher: Woodhead Publishing
Total Pages: 650
Release: 2016-09-13
Genre: Technology & Engineering
ISBN: 0081009119

Electrospun Nanofibers covers advances in the electrospinning process including characterization, testing and modeling of electrospun nanofibers, and electrospinning for particular fiber types and applications. Electrospun Nanofibers offers systematic and comprehensive coverage for academic researchers, industry professionals, and postgraduate students working in the field of fiber science. Electrospinning is the most commercially successful process for the production of nanofibers and rising demand is driving research and development in this field. Rapid progress is being made both in terms of the electrospinning process and in the production of nanofibers with superior chemical and physical properties. Electrospinning is becoming more efficient and more specialized in order to produce particular fiber types such as bicomponent and composite fibers, patterned and 3D nanofibers, carbon nanofibers and nanotubes, and nanofibers derived from chitosan. Provides systematic and comprehensive coverage of the manufacture, properties, and applications of nanofibers Covers recent developments in nanofibers materials including electrospinning of bicomponent, chitosan, carbon, and conductive fibers Brings together expertise from academia and industry to provide comprehensive, up-to-date information on nanofiber research and development Offers systematic and comprehensive coverage for academic researchers, industry professionals, and postgraduate students working in the field of fiber science