d-Band Holes React at the Tips of Gold Nanorods

Reactivehot spots on plasmonic nanoparticles have attracted attentionfor photocatalysis as they allow for efficient catalyst design. Whilesharp tips have been identified as optimal features for field enhancementand hot electron generation, the locations of catalytically promisingd-band holes are less clear. Here we exploit d-band hole-enhanceddissolution of gold nanorods as a model reaction to locate reactivehot spots produced from direct interband transitions, while the roleof the plasmon is to follow the reaction optically in real time. Usinga combination of single-particle electrochemistry and single-particlespectroscopy, we determine that d-band holes increase the rate ofgold nanorod electrodissolution at their tips. While nanorods dissolveisotropically in the dark, the same nanoparticles switch to tip-enhanceddissolution upon illimitation with 488 nm light. Electron microscopyconfirms that dissolution enhancement is exclusively at the tips ofthe nanorods, consistent with previous theoretical work that predictsthe location of d-band holes. We, therefore, conclude that d-bandholes drive reactions selectively at the nanorod tips.

Automated summary

We utilize the d-band hole-enhanced dissolution of gold nanorods as a model reaction to determine that d-band holes selectively drive reactions at the tips of the nanorods, increasing the rate of electrodissolution. The dissolution enhancement exclusively occurs at the tips of the nanorods upon illumination with 488 nm light, consistent with previous theoretical predictions.