Unifying the ORR and OER with surface oxygen and extracting their intrinsic activities on platinum.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39187503.
- Also identified by DOI 10.1038/s41467-024-51605-1 and PMC identifier 11347700.
- Licence recorded as CC BY-NC-ND.
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Abstract
Common half-cell measurements deliver oxygen reduction activities linked to the chosen scan rate, limiting their value for fundamental and comparative studies on platinum. Here we show a deconvolution of the intrinsic kinetics from the effect of surface oxygen on platinum. We find an electronic effect of the surface oxygen, substantiate a Tafel slope of ~120 mV/decade, obtain an exchange current density of 13 ± 4 µA/cm<sup>2</sup>, and an activity of 7 mA/cm<sup>2</sup> at 900 mV. Eventually, we broaden the scope of this analysis to the effects of surface rearrangement, alloying, and supported Pt nanoparticles, the latter providing insight into discrepancies between half-cell and fuel cell measurements. We find through computational methods that binding energies of intermediates would be weakened by the presence of highly coordinated oxygen atoms. Finally, we obtain a phenomenological rate equation for the oxygen reduction and evolution reaction, suggesting that both reactions follow a shared mechanism.