Pt Colloidosomes with Broadband Absorption for Near‐Infrared Light Photocatalysis through d‐Band Hot‐Carriers Generation

Interband and intraband electronic excitations in transition metals as nanocatalysts are crucial for the generation of hot carriers. Unlike the well‐known Au, Ag and Cu nanoparticles (NPs), in which hot carriers are directly formed by absorption of visible light, Pt NPs still have limited hot carriers photogeneration ability. Nonetheless, Pt's unique d‐band structure permits a high density of electronic states near Fermi energy. It should have exhibited photoenhanced catalysis. Here, guided by Finite‐Different‐Time‐Domain (FDTD) calculations, we take advantage of Pt electronic structure by designing a sub‐100 nm colloidosome (Cs) consisted of ultrasmall (≤ 5 nm) Pt NPs with broadband absorption from visible to near‐infrared (NIR) band. The ultrasmall Pt NPs in the Cs efficiently generated hot electrons even under excitation with the low‐energy electromagnetic radiation. The key for realization of Cs is the exploitation of laser‐generated, grain boundaries (GBs) enriched Mn3O4 NPs as scaffolds for the efficient and homogeneous loading of ultrasmall Pt NPs. These Pt Cs show outstanding performances as catalase (CAT) and oxidase (OXD) mimics under NIR band irradiation, allowing their use for photocatalysis of oxidation reactions. Besides, the in vivo exploitation of Pt Cs for tumor photodynamic therapy allowed unprecedented efficacy and caused tumor growth suppression.