Hot‐Electron Photodynamics in Silver‐Containing BEA‐Type Nanozeolite Studied by Femtosecond Transient Absorption Spectroscopy

Abstract

Silver cations were introduced in nanosized BEA‐type zeolite containing organic template by ion‐exchange followed by chemical reduction towards preparation of photoactive materials (Ag0‐BEA). The stabilization of highly dispersed Ag0 nanoparticles with a size of 1–2 nm in the BEA zeolite was revealed. The transient optical response of the Ag‐BEA samples upon photoexcitation at 400 nm was studied by femtosecond absorption. The photodynamic of the hot electrons was found to depend on the sample preparation. The lifetime of the hot electrons in the Ag−BEA samples containing small Ag nanoparticles (1–2 nm) is significantly shortened in comparison to bear Ag nanoparticles with a size of 10 nm. While for the larger Ag nanoparticles, the energy absorbed in the conduction band is decaying by electron‐phonon coupling into the metal lattice, the high surface‐to‐volume ratio of the small Ag nanoparticles favors the dissipation of the energy of the hot electrons from the metal nanoparticles (Ag0) towards the zeolitic micro‐environment. This finding is encouraging for further applications of Ag‐containing zeolites in photocatalysis and plasmonic chemistry.

Ultrafast formation of exciplex species in dicyanoanthracene ZSM-5 revealed by transient emission and vibrational spectroscopy

“…Owing to their remarkable architecture, constituting a regular porous 3D organization of cages and channels whose dimensions are comparable with the size of small chemical entities (molecules, metal complexes or nanoparticles), zeolites constitute a family of microporous materials that are very attractive to design photoactive supramolecular host-guest assemblies [1][2][3][4][5][6] and promising for applications in the fields of photocatalysis, nonlinear optical and luminescent materials, solar cell, sensing, photochemistry and environmental remediation. Not only the spatial organization in the void of the zeolite framework but also the effects of the confinement of guest compounds in the cages and channels result in novel photophysical and photochemical behaviors [7][8][9][10][11][12][13] that find their root in the earliest fs-ps processes following the photoexcitation [11,[13][14][15][16][17][18]. Therefore, elucidating the photophysical and photochemical processes governing these applications by ultrafast time-resolved spectroscopy contributes to the optimal and original development of these photoactive host-guest materials.…”