Hot spots engineering by dielectric support for enhanced photocatalytic redox reactions

Regulating the surface plasmon resonance (SPR) of metallic nanostructures is of great interests for optical and catalytic applications, however, it is still a great challenge for tuning SPR features of small metallic nanoparticles (< 10 nm). In this work, we design a unique dielectric support—urchin-like mesoporous silica nanoparticles (U-SiO₂) with ordered long spikes on its surface, which can well enhance the SPR properties of ~ 3 nm gold nanocrystals (AuNCs). The U-SiO₂ not only realizes the uniform self-assembly of AuNCs, but also prevents their aggregation due to the unique confinement effect. The finite-difference time-domain simulations show that the AuNCs on U-SiO₂ can generate plasmonic hot spots with highly enhanced electromagnetic field. Moreover, the hot electrons can be effectively and rapidly transferred through the interface junction to TiO₂. Thus, a high visible-light-driven photocatalytic activity can be observed, which is 3.8 times higher than that of smooth photocatalysts. The concept of dielectric supports engineering provides a new strategy for tuning SPR of small metallic nanocrystals towards the development of advanced plasmon-based applications.