Dataset of “Real-time probing of adsorption dynamics on Pt nanoparticles: Competitive interactions and site blocking in electrocatalysis”

Electrochemical energy conversion involves both steady-state and transient phenomena, with the latter being
difficult to probe under realistic conditions. Conventional in-situ/operando X-ray absorption spectroscopy often
lacks time resolution and provides mainly qualitative insights. In this study, we show that the 𝛥𝜇 XANES
method, applied on the Pt/H3PO3 system, enables potential-dependent tracking of surface speciation and
relative changes in adsorbate populations. It distinguishes H3PO3 concentrations and reveals competition for Pt
sites among O-, H-, CO-, H3PO3- and H3PO4-derived species. Despite XAS being bulk-sensitive, 𝛥𝜇 yields indirect
yet reliable surface information. Coupled with time-resolved fixed-energy X-ray absorption voltammetry
(FEXRAV), the transient evolution of the Pt electronic structure is monitored during CO stripping, revealing
dynamic electronic changes that precede the maximum electrochemical oxidation current. The complementary
use of FEXRAV and 𝛥𝜇 XANES correlates these transient electronic responses with the underlying surface
speciation, providing mechanistic insight into competitive adsorption on Pt. Machine learning validation
confirms predictive power despite low signal-to-noise ratio. This establishes the combination of 𝛥𝜇 XANES
and FEXRAV as a versatile tool for probing interfacial dynamics in fuel cells, electrolyzers, and CO2 reduction
technologies that can be readily implemented at conventional XAS beamlines.