Nanostructuring determines poisoning: tailoring CO adsorption on PtCu bimetallic nanoparticles

Here we show, combining CO stripping voltammograms on different PtCu nanoparticle (NP) low-temperature fuel cell electrocatalysts and density functional calculations, that surface chemical ordering and the presence of certain defects explain the CO tolerance vs. poisoning of such systems. The CO withdrawal for these duelling CO-slingers depends on whether they are well-shaped core@shell Cu@Pt NPs, more CO-tolerant, or having Cu-surrounded surface Pt atoms or adatoms/vacancies surface defects, less CO-tolerant. The latter sites are critical on nm-sized PtCu NPs, displaying stronger CO adsorption compared to pure Pt NPs. Avoiding such sites is key when designing less expensive and CO-poisoned Cu@Pt NP-based electrocatalysts.