Enhancing plasmonic photocatalysis via hotspot engineering in gold triorb core-satellite nanostructures

Exploiting energetic charge carriers generated on plasmonic nanoparticles forms the basis of photochemical transformations. The probability of generating hot electrons is higher in regions with significant electric field enhancement, called hotspots. Metal nanoparticles can be engineered to have these hotspots by introducing sharp curvatures or nanojunctions in the desired nanostructures. In this study, we demonstrate the utilization of nanojunction hotspots for photocatalytic hydrogen production from aqueous hydrazine. The plasmonic gold triorb nanostructure with a core-satellite architecture was synthesized via a wet-chemical approach by attaching multiple gold nanospheres (AuNS) onto the surface of a gold triangular nanoplate (AuTNP) by using a molecular linker. The nanogaps formed between the AuNS and the triangular nanoplate act as plasmonic hotspots, leading to enhanced optical responses and improved photocatalytic activities. The resulting photocatalyst (AuNS@TNP) was systematically compared to its individual constituents (AuNS and AuTNP) for photocatalytic hydrogen production from aqueous hydrazine. We find that the nanotriorb nanoconstruct shows a 4.3-fold and an 8-fold increase in the rate of hydrogen production compared to AuTNP and AuNS, respectively.