Water on well-defined platinum surfaces : an ultra high vacuum and electrochemical study
Niet, M.J.T.C. van der
Citation
Niet, M. J. T. C. van der. (2010, October 14). Water on well-defined platinum
surfaces : an ultra high vacuum and electrochemical study. Retrieved fromhttps://hdl.handle.net/1887/16035
Version: Corrected Publisher’s Version
License: Licence agreement concerning inclusion of doctoral thesis in the Institutional Repository of the University of Leiden
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WATER ON WELL-DEFINED PLATINUM SURFACES:
AN ULTRA HIGH VACUUM AND ELECTROCHEMICAL STUDY
PROEFSCHRIFT
ter verkrijging van
de graad van Doctor aan de Universiteit Leiden,
op gezag van de Rector Magnificus prof. mr. P. F. van der Heijden, volgens besluit van het College voor Promoties
te verdedigen op donderdag 14 oktober 2010 klokke 11.15 uur
door
Maria Johanna Theresia Cornelia (Janneke) van der Niet
geboren te Leiden in 1981
Promotiecommissie
Promotor: Prof. dr. M. T. M. Koper Co-promotor: Dr. L. B. F. Juurlink
overige leden: Prof. dr. M. Bonn (AMOLF/Universiteit van Amsterdam) Prof. dr. J. Brouwer
Prof. dr. B. E. Hayden (University of Southampton, UK) Dr. G. Held (University of Reading, UK)
Prof. dr. G. J. Kroes
Prof. dr. B. E. Nieuwenhuys
The research described in this thesis has been supported financially by NWO (Nether- lands Organization for Scientific Research), under project number 700-55-441.
Printed by F&N Boekservice ISBN 978-90-7867-595-2
Die Wissenschaft kann die letzten Rätsel der Natur nicht lösen. Und das ist so, weil wir letztlich selbst ein Teil des Rätsels sind, das wir zu lösen versuchen.
MAXPLANCK(1858–1947)
Table of Contents
1 Introduction 1
1.1 Heterogeneous catalysis . . . 1
1.2 Fuel cells . . . 2
1.3 Ultra high vacuum modeling . . . 3
1.4 Model catalysts . . . 3
1.5 Scope of this thesis . . . 4
1.6 Literature overview . . . 5
1.6.1 Water on platinum . . . 5
1.6.2 Oxygen on platinum . . . 6
1.6.3 Hydrogen on platinum . . . 7
1.6.4 Co-adsorption of H2O and Oadon platinum . . . 8
1.6.5 Co-adsorption of H2O and Hadon platinum . . . 9
1.6.6 Electrochemistry . . . 10
2 Experimental techniques and set-up 11 2.1 Ultra high vacuum . . . 11
2.1.1 Temperature programmed desorption . . . 11
2.1.2 Low energy electron diffraction . . . 12
2.1.3 Reflection absorption infrared spectroscopy . . . 13
2.1.4 Apparatus . . . 13
2.1.5 General procedures . . . 15
2.2 Electrochemistry . . . 17
2.2.1 Electrochemical cell . . . 17
2.2.2 Cyclic voltammetry . . . 18
2.2.3 Electochemical impedance spectroscopy . . . 18
3 The influence of step geometry on the desorption characteristics of O2, D2, and H2O from stepped Pt surfaces 21 3.1 Introduction . . . 22
3.2 Experimental . . . 24
3.3 Results and discussion . . . 24
3.3.1 Oxygen . . . 24
3.3.2 Deuterium . . . 26
3.3.3 Water . . . 30
3.4 Conclusion . . . 35 4 Co-adsorption of O and H2O on nano-structured platinum surfaces:
does OH form at steps? 37
v
TABLE OF CONTENTS
5 The interaction between H2O and pre-adsorbed O on the stepped Pt(533)
surface 45
5.1 Introduction . . . 46
5.2 Experimental . . . 49
5.3 Results and discussion . . . 49
5.3.1 O2adsorption/desorption . . . 49
5.3.2 H2O only . . . 50
5.3.3 Co-adsorption of18Oadand H216O . . . 52
5.4 Conclusion . . . 59
6 A detailed TPD study of H2O and pre-adsorbed O on the stepped Pt(553) surface 61 6.1 Introduction . . . 62
6.2 Experimental . . . 64
6.3 Results and discussion . . . 64
6.3.1 O2adsorption/desorption . . . 64
6.3.2 H2O desorption from the bare surface . . . 65
6.3.3 Co-adsorption of18Oadand H216O . . . 67
6.3.4 Unannealed Pt(553) surface . . . 75
6.4 Conclusion . . . 77
7 Tuning hydrophobicity of platinum by small changes in substrate mor- phology 79 8 Hydrophobic interactions between amorphous solid water and pre- adsorbed D on the stepped Pt(533) surface 87 8.1 Introduction . . . 88
8.2 Experimental . . . 89
8.3 Results . . . 90
8.4 Discussion . . . 97
8.5 Conclusion . . . 102
9 The interaction between H2O and pre-adsorbed D on the stepped Pt(553) surface 103 9.1 Introduction . . . 104
9.2 Experimental . . . 105
9.3 Results . . . 106
9.3.1 H2O and D2desorption from Pt(553) and D/Pt(553) . . . 106
9.3.2 θD= 1 ML; 0<θH 2O<2.28 ML . . . 107
9.3.3 θH2O≈1.3 ML; 0<θD<1 . . . 110
9.4 Discussion . . . 112
9.4.1 H2O and D2desorption from Pt(553) and D/Pt(553) . . . 112 vi
9.4.2 θD= 1 ML; 0<θH
2O<2.28 ML . . . 113
9.4.3 θH2O≈1.3 ML; 0<θD<1 . . . 115
9.5 Conclusion . . . 116
10 Impedance spectroscopy of H and OH adsorption on stepped single- crystal platinum electrodes in alkaline and acidic media 119 10.1 Introduction . . . 120
10.2 Experimental . . . 121
10.3 Results . . . 122
10.3.1 Pt(111) . . . 122
10.3.2 Stepped surfaces . . . 126
10.4 Discussion . . . 129
10.5 Conclusions . . . 132
11 Water dissociation on well-defined platinum surfaces: the electrochem- ical perspective 135 11.1 Introduction . . . 136
11.2 Experimental . . . 139
11.3 Results . . . 140
11.3.1 Pt[n(111)x(110)] . . . 140
11.3.2 Pt[n(111)x(100)] . . . 141
11.3.3 pH-dependence . . . 143
11.4 The model . . . 144
11.5 Water dissociation on well-defined platinum surfaces: the UHV per- spective . . . 146
11.6 Discussion . . . 147
11.7 Conclusion . . . 150
Appendix 151
Bibliography 153
Summary 165
Samenvatting 167
List of publications 171
Curriculum Vitae 173
Nawoord 175
Quotes 177
vii
