Critical thinking on baseline corrections for electrochemical surface area (ECSA) determination of Pt/C through H-adsorption/H-desorption regions of a cyclic voltammogram

Raghunandan Sharma*, Saso Gyergyek, Shuang Ma Andersen*

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Abstract

Determination of the electrochemical surface area (ECSA) of platinum supported on carbon (Pt/C) electrocatalysts through the hydrogen adsorption/desorption region has been revisited. Conventionally, ECSA is calculated by using the area of the H-adsorption (Had), H-desorption (Hde) or both of the regions to calculate the corresponding charge. Use of an appropriate baseline for the double-layer region is highly important for accurate determination of the associated charge. Unlike pure platinum, where a horizontal baseline for double-layer region is appropriate, the Pt/C catalysts have a skewed baseline for the double-layer region due to presence of surface functional groups from the support carbon. The skewness is not similar for the negative-going (cathodic) and the positive-going (anodic)scans, leading to significantly different Had and Hde charges. Again, the baselines from carbon may vary significantly during the catalyst durability study through an accelerated stress test (AST), due to oxidation of the support carbon. Present study investigates the effects of the baseline contribution on the ECSA calculations of Pt/C. It is observed that the baseline contribution for charge calculation (i) depends on the nature of the carbon support with significantly higher values (~10 fold) for Hde as compared to that for Had and (ii) increases for both the regions with the number of stress cycles during an AST. Hence, for Pt/C catalysts, while using a constant current baseline as a close approximation of the true baseline, charge associated to Had should be used for calculation of ECSA to access the catalyst activity as well as the durability in terms of %ECSA loss during AST.

OriginalsprogEngelsk
Artikelnummer121351
TidsskriftApplied Catalysis B: Environmental
Vol/bind311
Antal sider12
ISSN0926-3373
DOI
StatusUdgivet - 15. aug. 2022

Bibliografisk note

Funding Information:
The authors acknowledge Rikke Klindt Muller, IGT SDU for performing the surface area and thermogravimetry measurements. The authors also acknowledge the financial support from Innovation Fund Denmark, InnoExplorer Program, Nr. 9122-00112; Danish ESS Lighthouse on hard materials in 3D, SOLID, Grant number 8144-00002B; EnergiFyn udviklingsfond and Slovenian Research Agency (research core funding Nos. P2-0089).

Funding Information:
The authors acknowledge Rikke Klindt Muller, IGT SDU for performing the surface area and thermogravimetry measurements. The authors also acknowledge the financial support from Innovation Fund Denmark , InnoExplorer Program , Nr. 9122-00112 ; Danish ESS Lighthouse on hard materials in 3D, SOLID , Grant number 8144-00002B ; EnergiFyn udviklingsfond and Slovenian Research Agency (research core funding Nos. P2-0089 ).

Publisher Copyright:
© 2022 The Authors

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