Constructing Chiral Core–Shell–Satellite Superstructures for Highly Efficient Antenna–Reactor Hot Electron Generation

In hot electron (HE)-driven photocatalysis, plasmonic metal nanocrystals with small size, or even nanoclusters, are preferrable. Antenna–reactor mechanism has been utilized to further boost the photocatalytic performance of the small reactor nanoparticles. The construction of a metal–semiconductor–metal core–shell–satellite (CSS) superstructure is demonstrated for highly efficient HE generation of the entire CSS architecture, where a mesoporous TiO 2 (mTiO 2 ) shell spatially separates the Au nanohelicoid (AuNH) antenna core and Au nanocluster (AuNC) reactor satellites. Individual AuNH@mTiO 2 @AuNC CSS superstructures are optically characterized using dark field scattering and circular differential scattering spectroscopies. The HE and circular differential HE photocurrent responses of the CSS superstructures are measured using a photoelectrochemical cell, where 12.4- and 8.3-fold enhancements are respectively achieved with respect to that of the AuNHs. Electromagnetic simulations reveal that the contribution from the satellites with a small accumulative volume is almost equal to that from the core. Therefore, the specific-volume HE rate of the satellites exhibit a high amplification ratio, 350, with respect to that of the core, being attributed to the antenna–reactor mechanism in the CSS architecture. Key factors are optimized, which includes small size of the plasmonic satellites, E-field enhancement, and mesoporous semiconductor shell for efficient separation and collection of hot carriers.