Show/Hide Menu
Hide/Show Apps
Logout
Türkçe
Türkçe
Search
Search
Login
Login
OpenMETU
OpenMETU
About
About
Open Science Policy
Open Science Policy
Open Access Guideline
Open Access Guideline
Postgraduate Thesis Guideline
Postgraduate Thesis Guideline
Communities & Collections
Communities & Collections
Help
Help
Frequently Asked Questions
Frequently Asked Questions
Guides
Guides
Thesis submission
Thesis submission
MS without thesis term project submission
MS without thesis term project submission
Publication submission with DOI
Publication submission with DOI
Publication submission
Publication submission
Supporting Information
Supporting Information
General Information
General Information
Copyright, Embargo and License
Copyright, Embargo and License
Contact us
Contact us
Synthesis and characterization of water soluble polymer stabilized transition metal(0) nanoclusters as catalyst in hydrogen generation from the hydrolysis of sodium borohydride and ammonia borane
Download
index.pdf
Date
2010
Author
Metin, Önder
Metadata
Show full item record
Item Usage Stats
137
views
49
downloads
Cite This
Metal nanoclusters exhibit unique properties which differ from their bulk materials, owing to the quantum size effects. For example, the catalytic activity of transition metal nanoclusters generally increases with decreasing particle size. However, nanoclusters tend to be fairly unstable with respect to the agglomerate into bulk metal in solution and thus special precautions have to be taken to avoid their aggregation or precipitation during the preparation of such nanoclusters in solution. In order to obtain stable nanoclusters dispersed in solution, a stabilizing agent is usually added into the reaction system. The stabilization of metal nanoclusters in solution can be achieved either by electrostatically by using charged ions such as acetate ion or sterically by long chain molecules such as polymers. Polymers are one of the most widely used steric stabilizers for the preparation of stable metal nanoclusters in solution. The use of polymers as stabilizer for the synthesis of transition metal nanoclusters provides advantegous regarding solubility, conductivity, thermal stability and reusability. The metal nanoclusters stabilized by polymers generally show higher catalytic activity, stability and optical properties. In this dissertation we report the preparation and characterization of water soluble polymer stabilized transition metal(0) (metal= Ni, Co and Ru) nanoclusters and their v catalysis in hydrogen generation from the hydrolysis of sodium borohydride (NaBH4) and ammonia borane (AB) which are the best candidates as chemical hydrogen storage materials for on-board applications. The water soluble polymer stabilized nickel(0), cobalt(0) and ruthenium(0) nanoclusters were prepared by using two different facile methods; (i) the reduction of metal precursors by sodium borohydride in the presence poly(N-vinyl pyrrolidone) (PVP) in methanol solution after 1h reflux, (ii) the in situ generation during the hydrolysis of ammonia borane in the presence of poly(4-styrene sulfonicacid-co-maleic acid) (PSSA-co-MA). The characterization of both type of polymer stabilized transition metal(0) nanoclusters were done by using UV-Visible electronic absorption spectroscopy (UV-Vis), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and FT-IR techniques. The catalytic activity of PVP stabilized nickel(0), cobalt(0) and ruthenium(0) nanoclusters was tested in the hydrolysis of NaBH4 and AB. The catalytic acitivity of PSSA-co-MA stabilized nickel(0), cobalt(0) and ruthenium(0) nanoclusters was tested only in the hydrolysis of AB in which they were in situ generated. The kinetics of hydrogen generation from both hydrolysis reactions in the presence PVP or PSSA-co-MA stabilized nickel(0), cobalt(0) and ruthenium(0) nanoclusters were studied depending on the polymer to metal ratio, catalyst concentration, substrate concentration and temperature as well as the activation parameters (Arrhenius activation energy (Ea), activation enthalpy (∆H≠) and activation entropy (∆S≠) of both catalytic hydrolysis were calculated from the kinetic data.
Subject Keywords
Nanoclusters.
,
Chemistry.
,
Poly(N-viny- 2-pyrrolidone).
URI
http://etd.lib.metu.edu.tr/upload/12612717/index.pdf
https://hdl.handle.net/11511/20761
Collections
Graduate School of Natural and Applied Sciences, Thesis
Suggestions
OpenMETU
Core
Synthesis and Characterization of Micro Particles Templated from Cholesteric Liquid Crystal for Sensor Application
Avşar, Deniz Işınsu; Büküşoğlu, Emre (null; 2018-08-30)
Cholesteric liquid crystals (CLCs) are a fascinating genre among the liquid crystalline material family due to their unique optical properties arising from its periodic helical structure characterized by pitch length.[1]CLCs can reflect selected wavelengths of light within the visible wavelengths.The structural color change by temperature, chemicals, electric field, and magneticfield.[2] The ability to change the color in response to a suitable stimulus exhibit behavior that are forming the basis of numerou...
Synthesis and Structural Characterization of Multifunctional Ti Alloy: Gum Metal
Elçin, Orkun; Mekhrabov, Amdulla O.; Akdeniz, Mahmut Vedat (null; 2018-10-27)
A relatively new class of ȕ-phase having a body-centered cubic structure Ti alloy termed multifunctional titanium alloy (MFTA) or ‘Gum Metal’ with the composition of Ti-23Nb-07Ta-2Zr-O (mole %) has been shown to possess many interesting properties such as superplasticity at room temperature without extensive work hardening. In the heavily deformed state, it also possesses an ultra-low elastic modulus, ultra-high strength, large elasticity, and Elinvar and Invar properties. In this study, we have synthesized...
Synthesis and Characterization of Zirconium based Bulk Amorphous Alloys
Saltoğlu, İlkay; Akdeniz, Mahmut Vedat; Mehrabov, Amdulla (2005-09-28)
In recent years, bulk amorphous alloys and nanocrystalline materials have been synthesized in a number of ferrous and non-ferrous based alloys systems, which have gained some applications due to their unique physico-chemical and mechanical properties. In the last decade, Zr-based alloys with a wide supercooled liquid region and excellent glass forming ability have been discovered. These systems have promising application fields due to their mechanical properties; high tensile strength, high fracture toughne...
Synthesis of zinc oxide nanoparticles by aqueous methods and effect of metal incorporation on the structural/functional properties of nanoparticles
Altıntaş Yıldırım, Özlem; Durucan, Caner; Department of Metallurgical and Materials Engineering (2014)
Zinc oxide (ZnO) nanostructures have attracted considerable attention in many electrical, optoelectronic and magnetic applications due to their unique properties originating form characteristic wide band gap and large exciton binding energy of ZnO. Electrical, optical and magnetic properties of ZnO nanostructures strongly depend on their size and morphology. Therefore, there has been a strong interest in the synthesis of ZnO nanostructures with well-controlled size and shape. These synthesis approaches shou...
Synthesis and Characterization of a Quinoxaline and Benzodithiophene Comprising Multifunctional Polymer
Özdemir Hacıoğlu, Şerife; Yaşa, Mustafa; Depçi, Tolga; Göker, Seza; Toppare, Levent Kamil (null; 2019-12-03)
Conducting polymers have gained great interest recently due to their fascinating properties such as; solution processability, easy band gap alternation via structural modification, low cost and flexibility. Conducting polymers have variety of application fields like solar cells (OPVs), electrochromic devices, biosensors and light emitting diodes. Up to date, the donor-acceptor (D-synthesis of conducting polymers to obtain low band gap polymers for desired applications. Recently, quinoxaline and benzodithiop...
Citation Formats
IEEE
ACM
APA
CHICAGO
MLA
BibTeX
Ö. Metin, “Synthesis and characterization of water soluble polymer stabilized transition metal(0) nanoclusters as catalyst in hydrogen generation from the hydrolysis of sodium borohydride and ammonia borane,” Ph.D. - Doctoral Program, Middle East Technical University, 2010.