Photoreduction of Ag+ by Diethylaniline in colloidal zeolite nanocrystals

by Florence Luchez, Zakaria Tahri, Vincent De Waele, Ivan Yordanov, Svetlana Mintova, Alain Moissette, Mehran Mostafavi, Olivier Poizat

http://dx.doi.org/10.1016/j.micromeso.2014.04.008

Highlights

• Extra-framework Ag⁺ in colloidal zeolite Beta nanocrystals was photoreduced by amine.
• Subsequent early nucleation of silver atoms was followed by transient absorption.
• Ag⁰ is formed in less than 100 ns and is stable for more than one microsecond.
• Ag⁺ reduction likely arises if the amine is adsorbed on the zeolite particle surface.

Abstract

The photoinduced formation and the subsequent early nucleation steps of silver atoms (Ag⁰) in nanosized zeolite Beta crystals stabilized in aqueous colloidal suspensions are studied by steady-state UV-vis and Raman spectroscopy, and by transient absorption spectroscopy. The reduction of extra-framework silver cations is initiated by photoinduced electron transfer using organic electron donors such as N,N-diethylaniline or triphenylamine. The formation of Ag⁰ occurs in less than 100 ns and is found to be stable for more than one microsecond before beginning to aggregate, leading first to Ag₂⁺ species in ∼1.1 μs. The data suggest that the reduction of extra-framework Ag⁺ arises only if the electron donor species is adsorbed on the zeolite particle surface or within the channels.