Mie‐Resonance‐Enhanced Visible Light Absorption in Dielectric‐Supported Small Pt Nanoparticles for Photocatalysis.

Strong near‐field coupling between small catalytic Pt nanoparticles (NPs) and their dielectric supports can be achieved while visible light absorption in the Pt NPs is greatly enhanced via rationally designing the dielectric–Pt core–satellite configuration. Herein, it is demonstrated that the absorption enhancement is mediated by the Mie resonances of the support and the absorption peaks are induced by the magnetic Mie resonances. Utilizing both multipole decomposition analysis and numerical near‐field mapping, resonances including magnetic dipole, magnetic quadrupole, and higher modes are verified. For the generation of strong Mie resonances, a dielectric support with a high refractive index, like TiO2, can be used not only as the core directly, but also as a shell coated beneath or above the Pt NP layer. Additionally, the redshifts between the absorption peaks contributed by the Pt NPs and the scattering peaks contributed by the dielectric core are ascribed to the intrinsical spectral deviation between near‐ and far‐field optical properties. These findings benefit significantly both the fundamental understanding and optimized design of dielectric supported Pt photocatalysts, providing new opportunities for solar energy conversion and visible light photocatalysis using nonplasmonic catalytic transition metals. [ABSTRACT FROM AUTHOR]