Boosting energy transfer by plasmonic near-field effects on dendritic Pd–Au superstructures for hydrogen production and single-particle study

Hybrid plasmonic nanostructures exhibit strong interactions with incident light, providing new opportunities for activating the C–H bond in formic acid (HCOOH) for H 2 production. However, it remains a challenge to effectively exciting and extracting plasmonic energy into reactants. Herein, we report a facile strategy to boosting energy transfer by amplifying local electromagnetic field and elucidate plasmon-induced bond activation mechanism at single-particle level. Snowflake-like Pd-Au superstructures (Pd-Au SSs) were chemically synthesized through the selective growth of ordered perpendicular Pd nanoarrays on Au nanostars. Pd-Au SSs possess self-constructed hotspots and high surface-to-volume ratio, enabling efficient energy transfer. The obtained structures exhibited a turnover frequency (TOF) of 15,943 h −1 for H 2 production under plasmon excitation. Furthermore, in situ single-particle analysis showed that the photoluminescence (PL) density of individual Pd-Au SSs was reduced when immersed in HCOOH, which potentially implies that dehydrogenation process might involve indirect energy transfer through charge carriers and direct energy transfer by metal-adsorbate electronic states. Theoretical and experimental analyses revealed that the enhanced local electromagnetic field, which allows high rates of direct resonant transfer of charge from plasmonic nanostructures to the adsorbed molecules, makes significant contributions to C–H bond activation and H 2 production. This work not only provide valuable insights into plasmon-enhanced catalytic processes at single-particle level, but also establish a universal framework for designing novel high-performance multicomponent plasmonic nanostructures with precise geometries.