xiv CONTENTS
3.4 Stability measurements . . . . . . . . . . . . . . . . . . . . . . . 60
3.4.1 Electrochemical Quartz Crystal Microbalance . . . . . . . 60
3.4.2 Inductively Coupled Plasma - Mass Spectrometry . . . . 62
4 Benchmarking the stability of OER catalysts 65
4.1 Characterization of thin lms . . . . . . . . . . . . . . . . . . . . 65
4.2 Activity measurements . . . . . . . . . . . . . . . . . . . . . . . . 67
4.3 Stability measurements . . . . . . . . . . . . . . . . . . . . . . . 68
4.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
5 Towards a stable and inexpensive catalyst for OER in acid 75
5.1 MnOx thin lms in sulfuric acid . . . . . . . . . . . . . . . . . . . 76
5.2 A concept for improving stability of MnO2 . . . . . . . . . . . . . 79
5.2.1 Density Functional Theory . . . . . . . . . . . . . . . . . 80
5.2.2 Summary of DFT results for for MnO2 modications . . . 81
5.3 Experimental validation of the concept . . . . . . . . . . . . . . . 82
5.3.1 Stabilization in alkaline electrolyte . . . . . . . . . . . . . 89
5.3.2 Titania overlayers for stabilized MnO2 . . . . . . . . . . . 90
5.3.3 Cathodic dissolution in acid . . . . . . . . . . . . . . . . . 94
5.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
6 The benecial interaction between Au and MnOx 97
6.1 Theoretical model of Au-MnOx interaction . . . . . . . . . . . . 97
6.2 Experimental investigation of Au-MnOx catalysts . . . . . . . . . 102
6.2.1 Characterization . . . . . . . . . . . . . . . . . . . . . . . 103
6.2.2 Electrochemical characterization . . . . . . . . . . . . . . 106
6.2.3 In situ X-ray Absorption Near Edge Spectroscopy . . . . 108
6.3 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
7 Conclusion and outlook 119
7.1 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
7.2 Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Bibliography 123