Seed‐Engineered Growth of Sub‐100 Nm Chiral Au Nanoparticles with Enhanced Optical Chirality and Catalytic Activities

Size control of chiral plasmonic nanomaterials is of great significance for enabling diverse applications in nanophotonics, nanocatalysis, and biomedicine. Seed‐mediated chiral growth method allows the synthesis of chiral nanomaterials with tunable size and geometries; however, controllable synthesis of sub‐100 nm chiral nanomaterials with enhanced optical chirality remains challenging. Moreover, the quantitative understanding of the size‐dependent optical and catalytic activities remains elusive for sub‐100 nm chiral nanomaterials. Herein, a synthetic strategy is demonstrated to obtain sub‐100 nm chiral Au nanoparticles with enhanced optical chirality and catalytic activities. By engineering the starting seeds, precise control over sub‐100 nm chiral Au nanoparticles is achieved while maintaining their intrinsic chiral morphology, accompanied by enhanced optical chirality. The universality of this strategy is further demonstrated in achieving sub‐100 nm chiral nanoparticles with diverse sizes and geometries. By employing sub‐100 nm chiral nanoparticles as a core, enhanced tunable chiroptical signals can be observed in chiral metal‐semiconductor structures. Sub‐100 nm chiral Au nanoparticles also exhibit superior chiral electrooxidation activity compared to their larger counterparts (>100 nm). The work opens up a promising strategy for creating chiral nanomaterials with increasing structural diversity at the sub‐100 nm scale, which holds great promise for chirality‐dependent optical, catalytic, and biological applications.