Gap-Controlled Core-Satellite Assembly Nanostructures for Efficient Broadband Photocatalytic Hydrogen Evolution

The development of photocatalysts highly active in the visible-to-near-infrared light region is desired work for efficient solar energy conversion. Here, we introduce a newly designed plasmonic metal-semiconductor hybrid photocatalyst consisting of an Au core-satellite assembly and a crystalline TiO₂ shell. TiO₂ was used as a spacer to control the interparticle gaps between the Au nanocrystals to obtain the core-satellite assemblies. Following the additional growth of TiO₂ and calcination, the Au core-satellite assembly@TiO₂ core-shell nanostructures were successfully synthesized. Depending on the thickness of TiO₂, the gap distance between the core and satellite Au NCs was readily regulated in the same morphological unit. Thanks to this structural controllability, gap distance-dependent plasmonic and photocatalytic properties of Au nanocrystal assembly@TiO₂ structures were clearly elucidated. Nanostructures possessing the smallest interparticle distances between the core and satellite Au nanocrystals showed superb photocatalytic performance under the visible-to-near-infrared light irradiation attributed to the strong plasmon coupling between the Au nanocrystals and efficient hot electron transfer from the plasmon coupling site to TiO₂.