Two‐Dimensional Arrays of Au Halfshells with Different Sizes for Plasmon‐Induced Charge Separation

Abstract Plasmon‐induced charge separation (PICS) at plasmonic metal‐semiconductor interfaces has been used for photovoltaics, photocatalysis, and many other photofunctional materials and devices. In most of those cases, dispersed and disordered metal nanoparticle ensembles have been used. We prepared two‐dimensionally ordered and interconnected Au halfshell arrays on SiO 2 @TiO 2 core‐shell nanosphere colloidal crystals and exploited them for PICS. The present system exhibits broad light absorption over the visible to near‐infrared (NIR) range, leading to wide photoelectrochemical responses. Here we report that this system is characterized not only by localized and propagating surface plasmons but also by light propagation through the colloidal crystals, which enhances plasmonic light harvesting. Effects of the SiO 2 core size were examined, and the middle‐sized cores were found to be optimum for efficient PICS processes because of strong electric field at the photoelectrode.