Hydrido-chloroaluminium alkoxides and metal (Al, Ge) alkoxides-synthesis, characterization and applications for preparation of novel hydrogen storage nano-materials [Elektronische Ressource] / von Hameed Ullah Wazir
249 Pages
English

Hydrido-chloroaluminium alkoxides and metal (Al, Ge) alkoxides-synthesis, characterization and applications for preparation of novel hydrogen storage nano-materials [Elektronische Ressource] / von Hameed Ullah Wazir

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Hydrido/ChloroAluminium Alkoxides and Metal (Al, Ge) Alkoxides-Synthesis, Characterization and Applications for Preparation of Novel Hydrogen Storage Nano-Materials Dissertation zur Erlangung des Grades des Doktors der Naturwissenschaften der Naturwissenschaftlich-Technischen Fakultät III Chemie, Pharmazie, Bio- und Werkstoffwissenschaften der Universität des Saarlandes von Hameed Ullah Wazir Saarbrücken, Germany 2010 Tag des Kolloquiums: 09.12.2010 Dekan: Professor Dr.-Ing. Stefan Diebels Berichterstatter: Prof. Dr. Dr. h.c. Michael Veith PD Dr. Holger Kohlmann Vorsitz: Prof. Dr. Uli Kazmaier Akad. Mitarbeiter: Dr. Bernd Morgenstern To my Parents (Mum Zar Bano and Dad Bakht Alam), for their prayers, love, sacrifices and unwavering believe in me. To my wife (Sara), for her unconditional love, encouragement and support during the hardships of life I would like to extend my gratitude and thanks to my mentor/supervisor Prof. Dr. Dr. h. c. Michael Veith for giving me the opportunity to work under his guidance and introducing me to a novel research arena. The three and a half year Ph. D work under his supervision was a time of great opportunities for me to learn innovative ideas. I thank him for the wisdom and knowledge he has bestowed upon me during the course of my Ph. D work.

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Published 01 January 2010
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Hydrido/ChloroAluminium Alkoxides and Metal (Al, Ge) Alkoxides-
Synthesis, Characterization and Applications for Preparation of Novel
Hydrogen Storage Nano-Materials



Dissertation



zur Erlangung des Grades
des Doktors der Naturwissenschaften
der Naturwissenschaftlich-Technischen Fakultät III
Chemie, Pharmazie, Bio- und Werkstoffwissenschaften
der Universität des Saarlandes



von
Hameed Ullah Wazir




Saarbrücken, Germany
2010



















Tag des Kolloquiums: 09.12.2010
Dekan: Professor Dr.-Ing. Stefan Diebels
Berichterstatter: Prof. Dr. Dr. h.c. Michael Veith
PD Dr. Holger Kohlmann
Vorsitz: Prof. Dr. Uli Kazmaier
Akad. Mitarbeiter: Dr. Bernd Morgenstern








To my Parents
(Mum Zar Bano and Dad Bakht Alam),
for their prayers, love, sacrifices and unwavering believe in me.

To my wife (Sara),
for her unconditional love, encouragement
and support during the hardships of life





























I would like to extend my gratitude and thanks to my mentor/supervisor Prof. Dr. Dr. h. c.
Michael Veith for giving me the opportunity to work under his guidance and introducing me
to a novel research arena. The three and a half year Ph. D work under his supervision was a
time of great opportunities for me to learn innovative ideas. I thank him for the wisdom and
knowledge he has bestowed upon me during the course of my Ph. D work. His energetic and
untiring working style will be a role model for me in my entire life.


i I would like to extend my gratitudes to Prof. Dr. U. Kazmaier, PD Dr. H. Kohlmann and Dr.
B. Morgenstern for review and assessment of my thesis.

I have worked in two different locations during the course of my Ph. D study; at Leibniz
Institute of New Materials (INM) and Institute of Inorganic Chemistry, University of
Saarland. Therefore, I have been helped by many people in the two institutes in different ways
whenever I needed their help and support.

First of all I thank the INM administration for providing me generous facilities for conduction
of my research work. I extend my cordial thanks to Dipl. Ing. Dietmar Serwas and his team-
mates, Herbert Beerman, Uwe Magar, Michael Schneider and Werner Schneider for helping
me in construction of Sievert’s type apparatus and their continuous technical help during my
entire working period at INM. My sincere gratitude goes to the team of microscopy and X-ray
analytics at INM, Dr. Herbert Schmid, Dr. Ingrid Grobelsek, Dr. Marcus Koch and Mrs. Aude
Haettich for SEM, EDX, TEM and SAED analysis. I thank the two ladies, Elke Bubel and
Melanie Groh at the library of INM for their kindness and support while lending the books
and other reading materials. I thank Mr. Wolfgang Türk and his team of the EDV for
providing computer facilities although he did not allow me to access my social networking
sites. I would like to exploit the opportunity to forward my thanks to Dr. Oral Cenk Akta
for his unconditional help, support and guidance through various problems I faced during the
stay at INM. I thank my colleagues at INM, Dr. Hakima Smail, Cecile Dufloux, Dr. Michael
Bender, Carsten Bubel, Marina Martinez Miro, Cagri Kaan Akkan and Ju Seok Lee with
whom I shared some light moments.

At the institute of Chemistry I have been helped by many persons regarding my research
work. I thank Dr. Andreas Rammo for introducing me to the research group when I joined
the group in 2007. He taught me how to work at stock apparatus under inert atmosphere and
vacuum? I thank Dr. Markus Ehses for his valuable comments and proof reading of part of
the thesis. I thank him for reading, commenting and forwarding my annual reports to DAAD.
He helped me each and every time with smiling face whenever I asked.

I thank Dr. Volker Huch for single crystal analysis of all the compounds presented in the first
part of my research work. I thank him also for powder XRD analysis of my samples presented
in the second part of the thesis. A light chit-chat with him always gave me an immense
ii pleasure during my stay in the institute of Inorganic Chemistry. I thank Dr. Holger
Kohlmann for helping me in DSC analysis and his highly valuable comments. I thank him
from the core of my heart for giving me access to the DSC instrument in his lab facility and
providing me the acquired data and software whenever I needed.

27
My sincere thanks go to Dr. Michael Zimmer for solid state Al NMR and temperature
controlled NMR analysis. The valuable discussions with him were a source of knowledge for
27me in the field of Al NMR spectroscopy. I thank Mrs. Susanne Harling for the elemental
analysis of all the compounds presented in the first part of my thesis. I would like to thank the
technical staff at Institute of Chemistry, Hermann Recktenwald, Sylvia Beetz, Evelyne
Altmeyer, Andreas Adolf, Günther Berlin and Armin Kempf for their support and kindness.

I thank my colleagues (dicke Freunde) in Lab 350, Tatjana Kirs and David Kolano. The three
and half year time I spent with them will be remembered forever. The so friendly working
atmosphere in our Lab was more than enough for relaxing and avoiding depressions and
tensions of the workload as well as no results after experiments. I will miss them wherever I
will go. I thank my research fellows in the institute, Daniela Summa, Sandra Litzenburger,
Fadime Sahin, Amadou Lathyr Ndiaye and Andreas Walgenbach for their moral support, help
and moving around together.

I would exploit the opportunity to thank the Pakistani crew in Saarbrücken with whom I
enjoyed delicious Pakistani foods, cultural activities, get togethers and much more. It would
be an unjust (Khula Tezad), if I do not mention their names; Dr. M. Abbas, Dr. Habib-u-
Rehman, Dr. M. Awais Anwar, Dr. Safdar Ali, Amir F. Zahoor, M. Imran, A. waseem, M.
Zeshan Afzal, R. Hamza, W. Azim, Hussain Ali, Iftekhar Ahmed, Arif Khan, Saad Ullah,
Tousif Liaquat and all those whose names are not in my mind.

I would also extend my thanks to those on the other side of the world for their moral support,
love and encouragement. I thank my friends in Pakistan, M. Musa Khan and Gul Wali for
their friendship, moral support and prayers.

Last but not the least; I thank my parents for their patience, support, prayers. They always
believed in me and extended their every sort of support, unconditionally. They raised me to
the point where I am standing now. I thank my wife, Sara for her love, patience and
iii encouragement. She stood by me in every hardship of life and supported me through my
tough times. I thank her for arranging my birthday parties which I never celebrated before.



Hameed Ullah Wazir
Saarbrücken, 09.12.2010



























iv Abstract

The importance of strategy of syntheses and the characterisation of molecular precursors in
the bottom-up approach of the preparation of nano-materials is now generally accepted. For
the successful usage of this methodology, the knowledge of the molecular structure is
decisive, since the constituents of the target products are designed at molecular level.
Therefore, the purpose of this work was to synthesize molecular compounds of exactly known
structures and utilize these compounds for preparation of nano-materials as thin films and
powders for various uses.

In first part of this work, efforts are made to prepare structurally characterized molecular
compounds of the general formulae [H Al(OR) ] (n = 2 {1, 2, 5}, 1 {3, 6} or 0 {4, 7}; x = 2 n 3-n x
c c
{5, 6 7}, 4 {4}, 5 {1} or ∞ {2, 3}; R = Hex {1-4} or HexMe-1 {5-7}), [ClAl(H)(OR)] (R = 2
c cHexMe-1 {8}), [Cl Al(OR) ] (n = 1 {9} or 2 {10}; R = HexMe-1 {9-10}), [Ge(OR) ] n 3-n 2 2 2
c c i t(R = Hex {11} or HexMe-1 {12}, Pr {13}); [HAl(OR)(NR')] (R = Bu {14}, 2
c
HexMe-1 {15; R' = SiMe {14-15}). The molecular compounds 1, 2, 4, 5, 7, 8 - 12, 14 and 3
15 are obtained as crystalline powders and characterized by single crystal X-ray analysis as
1 13well as H, C NMR and IR spectroscopy. Crystals suitable for X-ray analysis could not be
grown for compound 3, 6 and 13. However, these compounds were characterized by NMR
and IR spectroscopy. Molecular compounds containing Al as central metal atoms were also
27characterized by Al NMR spectroscopy. The elemental compositions of all compounds were
determined by CHN analysis as well as by other complexometric titration techniques
wherever suitable.

In the second part of this thesis, the results of hydrogen adsorption studies with Al/Al O -2 3
composite nano-wires (NWs) and Ni/Al O -composite nano-powders (NPs) using a modified 2 3
Sievert apparatus are presented. Al/Al O -composites were prepared as thin films by the 2 3
decomposition of a molecular precursor, [H Al(OR)] , both upon steel as well as glass 2 2
substrates in a cold wall CVD reactor. Ni/Al O -composites were prepared as powders by the 2 3
decomposition of Ni(acac) under a steady stream of [H Al(OR)] in the same CVD set up, 2 2 2
using an adapted sample holder. Both types of materials, Al/Al O NW and Ni/Al O NP, 2 3 2 3
were characterized by XRD, SEM, TEM, EDXS, SAED and IR spectroscopy. Volumetric
hydrogen storage measurements with variable temperature and pressure showed a maximum
hydrogen uptake of 6.5(±0.2)wt.% with Al/Al O -composite NWs. The adsorption kinetics 2 3
v was followed by DSC and IR spectroscopy. The adsorption of hydrogen at the Al/Al O -2 3
composite NWs is controlled by pure physisorption at temperatures below 100°C while above
100°C, desorption occurs as a result of increasing temperature.


















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