Electrochemical deposition of cobalt, nickel-cobalt, nickel-copper and zinc-nickel nanostructured materials on aluminium by template selforganization [Elektronische Ressource] / von Adolphe Foyet

Elektrochemie

Informations

• Publié par: martin-luther-universitat_halle-wittenberg
• Publié le: 01 janvier 2007
• Nombre de lectures: 54
• Langue: English
• Poids de l'ouvrage: 3 Mo

Extrait

Electrochemical deposition of Cobalt, Nickel-Cobalt, Nickel-Copper and
Zinc-Nickel nanostructured materials on aluminum by template self-
organization


Dissertation

zur Erlangung des akademischen Grades
doctor rerum naturalium (Dr. rer. nat.)


vorgelegt der

Naturwissenschaftlichen Fakultät II - Chemie und Physik
der Martin-Luther-Universität Halle-Wittenberg


von Herrn M. sc. Adolphe FOYET

geb. am 11. 02. 1977 in Fotouni /Cameroon



Gutachter:

1. Prof. Dr. Wieland Schäfer
2. Prof. Dr. Michael Köhler

Halle (Saale), 24. 09. 2007

urn:nbn:de:gbv:3-000012352
[http://nbn-resolving.de/urn/resolver.pl?urn=nbn%3Ade%3Agbv%3A3-000012352]









This thesis is dedicated to my parents
TENKEU Michel and NGAPGOUE Anne


Contents
Contents…………………………………………………………………………………………..I
1. Introduction…………………………..………………………………………………………1

2. Preparation and characterization of nanoparticles and nanofilms……………………….4
2.1. Porous aluminum oxide as template for nanomaterial……………………………………..4
2.2. Surfactant and liquid crystal templates…………………………………………………….5
2.3. Characterization of mesoporous films…………………………………………...………...8
2.3.1. Scanning Probe techniques…………………………………………………………….8
2.3.2. Electrochemical impedance spectroscopy……………………………………………10
2.3.2.1. Data presentation………………………………………………………………...11
2.3.2.2. Impedance data analysis…………………………………………………………14

3. Experimental part……………………………….………………………………………….17
3.1. Reagents…………………………………………………………………………………..17
3.2. Preparation of templates………………………………………………………………….17
3.3. Electrochemical deposition and characterization…………………………………………18
3.3.1. Electrodeposition…………………………………………..…………………………18
3.3.2. Characterization……………………………………….……………………………...20
- Atomic force Microscopy and scanning tunneling microscopy………………………20
- Electrochemical impedance spectroscopy…………………………………………….20
- Semiconductivity measurements: Mott-schottky plot………………………………...22 ical noise measurement………………………………………………….22
- Polarization and corrosion measurements…………………………………………….22

4. Template deposition of cobalt nanoparticles……………………………………………...23
4.1. Preparation and characterization of porous alumina membrane (AAO)…………………23
4.1.1. Preparation of AAO……………………………………………………………….….23
4.1.2. Characterization of AAO: AFM and impedance spectroscopy……………………....25
4.2. Electrochemical deposition of cobalt from aqueous solution to the pore of AAO……….31
4.2.1. Influence of the deposition charge on the structure of cobalt nanomaterial…...……..31
4.2.2. Influence of the current density on the structure of cobalt nanomaterial…………….36
4.2.3. Electrochemical Impedance characterization of cobalt nanofilm on AAO…………..42
4.2.4. Discussion of the impedance results………………………………………………….45
4.2.5. Electrochemical deposition of single nanorod and clusters in the pores of AAO……46
i Contents
4.3 Deposition of cobalt in the AAO membrane using the hexagonal phase of lyotropic liquid
crystal: Double template electrodeposition………………………………………………....49
4.3.1. Preparation and characterization of liquid crystals mixtures…………………...….....49
4.3.2. Principle of double template deposition……………………………………………...51
4.3.3. Double template electrochemical deposition of cobalt……………………………… 52
- Direct current electrochemical deposition…………………………………………...52
- Pulse current electrochemical deposition……………………………………………54
4.3.4. Impedance spectra of cobalt film deposited from Brij 76 templating mixture….……61
4.4. Electrochemical behavior of cobalt nanoparticles in LiClO aqueous solution………….64 4
4.4.1. Anodic linear voltammetry and corrosion measurement…………………………......64
4.4.2. Electrochemical noise measurement……………………..………………………….. 67
4.4.3. Mott-Schottky analysis of cobalt nanofilm in Lithium perchlorate……..…………... 70
4.5. Partial conclusion…………………………………………………………………………74

5. Double template deposition and characterization of alloys nanoparticles…………….. 75
5.1. Preparation and characterization of ZnNi alloy nanoparticles…………………………... 75
5.1.1. Electrochemical deposition………………………………………………………….. 75
5.1.2. Polarization behavior of ZnNi alloy nanoparticles…………………………………...78
5.1.3. Electrochemical Impedance measurements…………………………………………..80
5.1.4. Corrosion and Mott-Schottky analysis………………………………………………. 82
5.2. Preparation and characterization of NiCu alloy nanoparticles………………………...…85
5.2.1. Electrodeposition of NiCu alloy……………………………………………………...85
5.2.2. Polarization and corrosion of NiCu alloy nanoparticles……………………………...87
5.2.3. Impedance and Mott-Schottky analysis of NiCu alloy nanoparticles……………….. 89
5.3. Electrodeposition and characterization of NiCo alloy nanoparticles……………………. 92
5.3.1. Electrochemical deposition………………………………………………………….. 92
5.3.2. Polarization and corrosion measurements……………………………………………94
5.3.3. Impedance and Mott-Schottky analysis of NiCo nanoparticles………………………96
5.4. Discussion……………………………………………………………………………...…98

6. Summary………………………………………………………..…………….……………101

7. References…………………………………………………………………………………..104

ii Contents
8. Appendix……………………………………………………………………………………111
8.1. X-ray diffraction of cobalt nanoparticles……………………………………………….111
8.2. Phase diagram of surfactants used in double template deposition……………………..112
8.3. Working hypothesis for impedance measurement..…...………………………………..113
8.4. Fitting of Impedance data and calculation of Z(j ω) equations………………………...114
8.3.1. Impedance of alumina membrane…………………………………………………..114
8.3.2. Impedance of cobalt film deposited from aqueous solution into AAO…………….117
8.3.3. Im Brij 76 into AAO……………………….118
8.3.4. Impedance model of alloys nanoparticles…………………………………………..120
8.5. Principle of Atomic force Microscopy (AFM)…………………………………………121

Acknowledgements
Conferences and publication
Curriculum Vitae




















iii Contents

Abbreviations

AFM Atomic force microscope
AAO Anodic aluminum oxide
STM Scanning tunneling microscope
SEM Scanning electron microscope
TEM Transmission electron Microscope
SPM Scanning probe microscopes
SCE Saturated calomel electrode
RE Reference electrode
CE Counter electrode
WE Working electrode
Brij 76 Decaethyleneoxide monooctadecyl ether (C EO ) 18 10
Brij 78 Polyoxyethylene(20)stearylether (C EO ) 18 20
CTAB Hexadecyltrimethyammonium bromide
SAXS Small angle x-ray scattering
DC Direct current
AC Alternative current
RMS Root mean square roughness
EIS Electrochemical impedance spectroscopy
ALSV Anodic linear sweep voltammetry
EN Electrochemical Noise
PSD Power spectra density
Csc Space charge capacitance
C Double layer capacitance dl
Rp Polarization resistance
MS Mott-Schottky
FFT Fast Fourier Transform




iv
Introduction
1. Introduction

One of the great sc