posted on 2018-08-06, 00:00authored byMohamad El-Roz, Igor Telegeiev, Natalia E. Mordvinova, Oleg I. Lebedev, Nicolas Barrier, Asma Behilil, Moussa Zaarour, Louwanda Lakiss, Valentin Valtchev
Sub-nanometer silver
clusters that exhibit discrete electronic structure with molecular-like
properties are highly desirable in various technologies. However,
the methods for their preparation suffer from limitations related
with the reproducibility and particles uniformity and/or the possibility
of the scale-up. Another critical drawback is that free sub-nanometer
silver clusters tend to aggregate into larger particles. In this work,
a new approach that successfully overcomes the above limitations is
developed. It allows, for the first time, an ultrafast preparation
of sub-nanometer silver particles with high abundance, uniformity
(7 Å), and stability into the cages of nanosized zeolite crystals.
The new method consists of UV excitation of a water suspension of
nanozeolite containing photoactive vanadate clusters in the presence
of ethanol (as an electron donor) and silver precursor. The characteristic
features of sub-nanometer silver particles are presented, and the
mechanism of their formation is discussed. Sub-nanometer Ag clusters
exhibit exceptional photocatalytic activity and selectivity in the
reforming of formic acid to H2 and CO2 under
visible light.