Two Excited State Collaboration of Heteroleptic Ir(III)-Coumarin Complexes for H2 Evolution Dye-Sensitized Photocatalysts
نویسندگان
چکیده
Interfacial electron injection from a photoexcited surface-immobilized dye to semiconductor substrate is key reaction for dye-sensitized photocatalysts. We previously reported that the molecular orientation of heteroleptic Ir(III) photosensitizer on TiO2 nanoparticle surface was important efficient interfacial injection. In this work, overcome weak light absorption ability and improve photoinduced charge-separation efficiency at dye–semiconductor interface, we synthesized two complexes with different coumarin dyes, [Ir(C6)2(H4CPbpy)]Cl [Ir(C30)2(H4CPbpy)]Cl [Ir-CX; X = 6 or 30; HC6 3-(2-enzothiazolyl)-7-(diethylamino)coumarin, HC30 3-(2-N-methylbenzimidazolyl)-7-N,N-diethylaminocoumarin, H4CPbpy 4,4′-bis(methylphosphonic acid)-2,2′-bipyridine], as cyclometalated ligands immobilized them Pt-cocatalyst-loaded nanoparticles. Ultraviolet-visible emission spectroscopy revealed singlet ligand-centered (1LC) triplet 3LC bands Ir-C30 occurred shorter wavelengths than those Ir-C6, while time-dependent density-functional-theory data suggested ligand-to-ligand charge transfer (LLCT) excited states were comparable. The photocatalytic H2 evolution activity Ir-C6-sensitized Pt-TiO2 nanoparticles (Ir-C6@Pt-TiO2) under visible irradiation (λ > 420 nm) higher Ir-C30@Pt-TiO2. contrast, their activities comparable monochromatic 450 ± 10 nm), which absorbed comparably by both Ir-CX complexes. These results suggest internal conversion higher-lying LC state LLCT effectively occurs in trigger TiO2.
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ژورنال
عنوان ژورنال: Energies
سال: 2021
ISSN: ['1996-1073']
DOI: https://doi.org/10.3390/en14092425