Heterogeneous Reactivity of Palladium Nanoparticles Revealed by Wavelength-Resolved Interferometric Scattering

High Resolution Image Download MS PowerPoint Slide Pd nanoparticles are used in a variety of applications, and thus techniques that enable their high-throughput, label-free detection, as well as in situ reaction monitoring at catalytically relevant sizes, are needed to establish robust structure–function relationships. Here, we introduce wavelength-resolved interferometric scattering (iSCAT) as a strategy for performing these studies, over a range of Pd nanoparticle sizes. From a sample of ∼90 nm Pd octahedra we spectroscopically discriminate structural outliers based on their scattering resonances and spectral lineshapes, using simulations to validate the structure–spectral relationships. We then demonstrate direct detection of single Pd nanocubes with <20 nm edge length and track changes occurring to them in different reactive conditions, uncovering both interparticle heterogeneity and wavelength-dependent photochemistry. The results highlight the power of wavelength-resolved iSCAT for studying Pd nanoparticle transformations in situ and offer new insights into Pd reactivity at the nanoscale.