Steric hindrance-induced selective growth of rhodium on gold nanobipyramids for plasmon-enhanced nitrogen fixation

Abstract

The construction of an antenna–reactor plasmonic photocatalyst that is composed of a plasmonic and a catalytically active metal holds great promise in driving N₂ photofixation, but its photocatalytic performance is highly dependent on the spatial distribution of the two components. Up to now, the fabrication of dumbbell-shaped nanostructures featuring spatially separated architecture has remained challenging. Herein, we develop a facile synthetic strategy for the site-selective growth of a Rh nanocrystal ‘reactor’ on two tips of an Au nanobipyramid (NBP) ‘antenna’ through the precise manipulation of steric hindrance toward Rh overgrowth. The obtained Au NBP/tip-Rh nanodumbbells (Au NBP/tip-Rh NDs) can function as an excellent antenna–reactor plasmonic photocatalyst for N₂ photofixation. In this scenario, the Au nanoantenna harvests light and generates hot electrons under plasmon resonance, meanwhile the hot electrons are transferred to the active sites on Rh nanocrystals for N₂ reduction. In comparison with that of classical core@shell nanostructures, the spatially separated architecture of the Au NBP/tip-Rh NDs facilitates charge separation, greatly improving the photocatalytic activity. This study sheds new light on the structure–function relationship for N₂ photofixation and benefits the design and construction of spatially separated plasmonic photocatalysts.