Burying small Pt nanoparticles in the TiO 2 microsphere support to form visible light antenna-reactor photocatalysts.

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.