Abstract
Recently, loading ligand-protected gold (Au) clusters as visible light photosensitizers onto various supports for photoredox catalysis has attracted considerable attention. However, the efficient control of long-term photostability of Au clusters on the metal-support interface remains challenging. Herein, we report a simple and efficient method for enhancing the photostability of glutathione-protected Au clusters (Au GSH clusters) loaded on the surface of SiO2 sphere by utilizing multifunctional branched poly-ethylenimine (BPEI) as a surface charge modifying, reducing and stabilizing agent. The sequential coating of thickness controlled TiO2 shells can further significantly improve the photocatalytic efficiency, while such structurally designed core-shell SiO2-Au GSH clusters-BPEI@TiO2 composites maintain high photostability during longtime light illumination conditions. This joint strategy via interfacial modification and composition engineering provides a facile guideline for stabilizing ultrasmall Au clusters and rational design of Au clusters-based composites with improved activity toward targeting applications in photoredox catalysis.
Highlights
Loading ligand-protected gold (Au) clusters as visible light photosensitizers onto various supports for photoredox catalysis has attracted considerable attention
UV-vis absorption spectrum of Au GSH clusters in Supplementary Fig. 1c suggests that the Au GSH clusters show an absorption onset at ∼520 nm with a distinct shoulder around 400 nm, which is attributed to the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) transition originated from the ligand-to-metal charge transfer[15], indicating that Au GSH clusters could be used as visible light photosensitizers
The PL emissive spectra of Au GSH clusters with different excitation wavelengths in Supplementary Fig. 1f show a low energy emission band with the peak maximum at 605 nm, which is ascribed to the triplet metal-centered state[32], and the shape of the PL spectra is independent of the excitation wavelength[15]
Summary
Loading ligand-protected gold (Au) clusters as visible light photosensitizers onto various supports for photoredox catalysis has attracted considerable attention. The sequential coating of thickness controlled TiO2 shells can further significantly improve the photocatalytic efficiency, while such structurally designed core-shell SiO2-Au GSH clusters-BPEI@TiO2 composites maintain high photostability during longtime light illumination conditions. This joint strategy via interfacial modification and composition engineering provides a facile guideline for stabilizing ultrasmall Au clusters and rational design of Au clusters-based composites with improved activity toward targeting applications in photoredox catalysis. We report a simple, combinatorial approach to stabilize ultrasmall Au GSH clusters on the SiO2 sphere support and improve their photocatalytic efficiency by using multifunctional branched poly-ethylenimine (BPEI) for surface modification and coating thickness controlled semiconductor TiO2 shell for interfacial composition engineering. The strategy via interfacial modification and composition manipulation by coating semiconductor shell provides an efficient way for stabilizing Au clusters with improved photocatalytic activity, which is anticipated to enable the broad development of Au clusters-based composite system for photoredox applications in solar energy conversion
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