SHINing Light on Interfacial Electrochemical Reactions

Fernandez Vidal, Julia ORCID: 0000-0002-0856-2927 (2022) SHINing Light on Interfacial Electrochemical Reactions. PhD thesis, University of Liverpool.

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Abstract

The oxygen reduction reaction (ORR) is one of the most important electrochemical processes in energy conversion and storage. The slow reaction kinetics has become a long recognised challenge, thereby requiring a catalyst to promote the rate of reaction. To date, Pt is the most active and stable single compound that can catalyse the ORR. However, after many years of study, the detailed surface mechanism of the ORR is still not fully understood, due the inability of the commonly used experimental techniques to detect reaction intermediates. Understanding the basis and fundaments of the ORR on Pt surfaces is a necessary step for the design and development of practical and efficient catalysts. The use of Pt single crystals simplifies the study and opens the possibility of correlating specific interfacial properties with the electrochemical processes occurring at the interface. Traditionally, electrochemistry has been involved in the elucidation of the ORR mechanisms on Pt single crystal surfaces. Despite being a useful method to obtain kinetic information, this technique by itself is not suitable for chemical identification and detection of intermediates and products of redox and side reactions taking place in the electrode|electrolyte interface. The combination of electrochemical experiments with in situ spectroscopy, in what is known as spectro-electrochemistry, can provide information on the chemical nature of electrochemical interfaces, electron-transfer processes and redox reaction intermediates and kinetics. While spectro-electrochemistry has been a major activity over the past few decades, its application in certain fields has only recently become more extensive since specialised equipment has been necessary to carry out these studies. In this sense, the importance of the central role that Raman spectroscopy and, specifically, the shell-isolated nanoparticles for enhanced Raman spectroscopy (SHINERS) method have played in recent years is noteworthy. Synthesis and characterisation of SHINERS is carried out in this thesis and the use of differential centrifugal sedimentation (DCS) is suggested to measure the shell thickness. The relevance of the shell material choice is considered in this work and emphasis has been attracted on tin (IV) dioxide-coated SHINERS. Likewise, in situ Raman spectroscopy (in situ EC-SHINERS) results on electrified Pt (hkl) interfaces are discussed in both aqueous and non-aqueous electrolytes.

Item Type:	Thesis (PhD)
Divisions:	Faculty of Science and Engineering > School of Physical Sciences
Depositing User:	Symplectic Admin
Date Deposited:	25 Aug 2023 12:38
Last Modified:	25 Aug 2023 12:39
DOI:	10.17638/03165906
Supervisors:	Hardwick, Laurence J ORCID: 0000-0001-8796-685X Cowan, Alex
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3165906