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The design of antenna–reactor photocatalysts has become a powerful strategy to covert transition metal reactors from traditional thermocatalysts to novel photocatalysts. Plasmonic metals are often used as the optical antenna. Here, we demonstrate that conventional dielectric supports with high refractive index are able to achieve comparable performance as the plasmonic antennas, giving rise to a huge enhancement of the visible light absorption in the small Pt nanoparticles (NPs) of the core–satellite antenna–reactor photocatalysts through resonance energy transfer. The absorption enhancement can be mediated not only by the electric resonances of the plasmonic antenna but also by the magnetic resonances of the dielectric antenna. A large enough dielectric antenna or a small plasmonic antenna is desired for the generation of strong optical resonances. Judged by those Pt NPs with strong visible light absorption enhancement, the potential catalytically active sites are mainly distributed at the back side of the dielectric antenna, while they may be widely distributed over the surface of the plasmonic antenna with probably lower activities. The expanding scope of antenna–reactor photocatalysts offers new opportunities for solar to chemical energy conversion using nonplasmonic catalytic transition metals. [ABSTRACT FROM AUTHOR]

By rational design and parameter engineering of the TiO 2 -Pt core-satellite construction, visible light absorption in small Pt nanoparticles (NPs) can be enhanced by nearly 100 times. The TiO 2 microsphere support works as the optical antenna, giving rise to superior performance compared to conventional plasmonic nanoantennas. A crucial step is to bury the Pt NPs completely in the high refractive index TiO 2 microsphere, because light absorption in the Pt NP approximately scales with the fourth power of the refractive index of its surrounding media. The proposed evaluation factor for light absorption enhancement in the Pt NPs at different positions is proved to be valid and useful. The physics modeling of the buried Pt NPs corresponds to the general case in practice where the surface of the TiO 2 microsphere is naturally rough or a thin TiO 2 coating is subsequently added. These results offer new avenues for directly transforming dielectric supported nonplasmonic catalytic transition metals into visible light photocatalysts.