Fundamental Study of Adsorbed Intermediates of the Pt-Catalysed Oxygen Reduction Reaction

Lead Research Organisation: University of Southampton
Department Name: Sch of Chemistry

Abstract

The initial objectives of this study have been to extend the work on microelectrodes to polycrystalline Pt macroelectrodes to establish a Pt-specific charge density associated with the reduction of Oads. Microelectrodes possess unique properties which facilitated the discovery of Oads but these species have now been observed using cyclic voltammetry at rotating disc electrodes (RDE), displaying a stripping peak characteristic of the reduction of surface-bound species. This observation could enable the study of Oads at real LTFC catalysts using well established methodologies for catalyst deposition on RDE. 1This presentation discusses the results obtained at macroelectrodes which support previous conclusions, and illustrates the sensitivity of fundamental techniques in electroanalysis.

Publications

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Tammy Jessica Nimmo (2021) The role of water in the electrochemical response of platinum

Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509747/1 30/09/2016 29/09/2021
1948275 Studentship EP/N509747/1 30/09/2017 29/09/2020 Tammy Nimmo
 
Description The oxygen reduction reaction (ORR) and formation of oxide occur simultaneously on the surface of platinum catalysts in the range of the open circuit potential (OCP) of electrochemical gas sensors and fuel cells. The relationship between these processes relies on a fundamental understanding of the reactivity of water as a proton donor at the interface. The first part of this work used OCP measurements to study the parallel oxygen and oxide electrochemistry of platinum rotating disc electrodes. The OCP was shown to be controlled by the kinetics of the ORR, which depended on the nature and coverage of oxide in acid but was independent of oxides present in low quantities in alkaline solution. The formation of oxide at rest was found to be pH dependent, with the coverage being higher and the oxide more strongly bound in alkaline media than in acid. The oxides were gradually transformed into a more strongly coordinated form with time. The second part of this work controlled the availability of water in the ORR at microelectrodes by the systematic addition of water to nonaqueous electrolytes. Organic and alkali metal cations with different abilities to coordinate water were used to modify its presence in the double layer and its reactivity in proton transfer. Comparison of platinum and gold as electrode materials revealed that the ability of the metal to bind and dissociate water is an important descriptor for proton transfer in the ORR. It was shown that there is a balance between the affinity of the surface for H2O and its site blocking effect when coordinated to metal ions. The results emphasized the importance of the relative strengths of interactions between each of the species in the system, Pt, H2O, M+, and O2 , in determining the reactivity of water in the ORR.
Exploitation Route As part of the work associated with this funding, a 3D printed electrochemical gas flow cell has been designed and optimized along with gas mixing apparatus to allow facile testing of different assemblies of gas diffusion Pt catalyst electrodes and ionic liquid based solid polymer electrolytes for carbon monoxide sensing. The use of this apparatus for further gas testing and optimization will extend beyond the scope of this research project. This and other findings associated with this research can be built upon in the future to establish more advanced/solid conclusions in the field by future members of the Electrochemistry group at the University of Southampton.
Sectors Chemicals

Other
 
Title Supporting data: The role of water in the electrochemical response of platinum 
Description Data supporting the PhD thesis: The role of water in the electrochemical response of platinum. The dataset includes the raw data associated with electrochemical experiments to study the OCP of platinum and gold rotating disc electrodes in N2 and O2 purged HClO4 and NaOH electrolyte, and experiments to study the effect of water addition on the oxygen reduction reaction at platinum and gold microdisc electrodes in dimethyl sulfoxide containing TBA+, Na+ and K+ cations in the supporting electrolyte salts. Experimental details for each file can be found by looking in the relevant chapters in the thesis. The raw electrochemical data includes cyclic voltammetry, chronoamperometry and chronopotentiometry in the form of text files. 
Type Of Material Database/Collection of data 
Year Produced 2021 
Provided To Others? No  
Impact The data collected in this project has contributed to further understanding the processes underpinning the electrochemical reactions of platinum electrodes in aqueous environments with applications in electrochemical gas sensing and fuel cell technologies. The data is therefore relevant to further developments in these projects by future members of the Electrochemistry group at the University of Southampton. In addition, three publications are in preparation as a result of the data collected. 
 
Description Oral presentation at SCI Electrochemistry Postgraduate Conference (University of Southampton) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Postgraduate students
Results and Impact As part of the SCI Electrochemistry Postgraduate Conference (within the first year of my PhD candidature) I gave a 20 minute oral presentation on my research using Microsoft Office PowerPoint. This was followed by questions from the audience and the opportunity for further discussion and exchange of ideas during networking sessions. The purpose of presenting my work at this conference was to engage other electrochemists with my research as well as to receive feedback and new insight on my work from academics, research fellows, and other postgraduate students, and this was achieved through questions and discussion. The exercise also served to increase my skill in communicating my research to a large audience. A report of the conference is available at the website URL given below.
Year(s) Of Engagement Activity 2017
URL https://sites.google.com/site/sciepc2017/programme
 
Description Poster presentation at 69th Annual Meeting of the International Society of Electrochemistry (Bologna) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact As part of the 69th Annual Meeting of the International Society of Electrochemistry (within the second year of my PhD candidature) I presented a poster and engaged with other postgraduate students, research fellows and academic professors about my research. The purpose of presenting my work at this conference was to receive feedback and new insight on my work from the perspective of international researchers with different expertise in the field, as well as to increase awareness of my research. This was achieved during the discussions which were exchanged. The outcome of some of these discussions was to make me aware of relevant publications and other resources specific to certain aspects of my research that allowed to more fully investigate the claims of my work and helped to shape the progress of my research. The abstract for this poster is available in the book of abstracts at the website URL given below.
Year(s) Of Engagement Activity 2018
URL https://www.ise-online.org/ise-conferences/annmeet/folder/69th_Annual_meeting-BoA.pdf
 
Description Poster presentation at the Electrochem2019 Conference (Glasgow) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact As part of the Electrochem2019 Conference (within the third year of my PhD candidature) I presented a poster and engaged with other postgraduate students, academics and professional research scientists about my research. The purpose of presenting my work at this conference was to receive feedback and new insight on my work from the perspective of national and international researchers with different expertise in the field, as well as to increase awareness of my research. Particularly useful discussions resulted in email correspondence in order to receive information about specific experimental methods related to conducting measurements which later helped to increase the progress of the research. Additional fruitful discussion resulted in confirmation from the audience (expert industrial research scientist) about further progress which could be made to contribute to the research field based on the outcomes presented in the poster. The abstract for this poster is available in the book of abstracts at the website URL given below.
Year(s) Of Engagement Activity 2019
URL https://www.strath.ac.uk/media/1newwebsite/departmentsubject/engineering-chemicalprocess/events/Abst...