A repertoire of gold-based nanostructures with integrated optical and catalytic tunabilities

Au nanoparticles exhibit geometry-dependent optical characteristics dictated by localized plasmon resonances and intriguing catalytic properties intimately tied to their atomic-level surface structures. While the dimensions of well-performing plasmon resonators typically range from tens of nanometers to submicrons, heterogeneous catalysis usually entails the use of much smaller nanoparticulate Au catalysts in the sub-5 nm size regime. Due to such a size gap, merging optical and catalytic tunabilities in a single Au nanoparticle has been a challenging task. In this feature article, I review several paradigm-shifting strategies for integrating tunable optical and catalytic properties within single Au-based nanostructures that are experimentally realizable. These strategies include nanoscale surface roughening of Au nanoparticles, creation of nanoporosity inside Au nanoparticles, facet control of anisotropic Au nanostructures, growth of Au nanocrystals with intrinsic structural chirality, and alloying Au with other metal elements in nanoparticles. By going through several case studies, I further elaborate on how the optical and catalytic properties can be judiciously tuned in a selection of dual-functional Au-based nanostructures to enable real-time monitoring of molecular transformations at the catalyst-adsorbate interfaces through in situ plasmon-enhanced spectroscopic measurements and kinetic modulation of catalytic/photocatalytic reactions through optical excitations of plasmonic electron oscillations and interband electronic transitions.