A Recycling-Free Nanocatalyst System: The Stabilization of In Situ-Reduced Noble Metal Nanoparticles on Silicone Nanofilaments via a Mussel-Inspired Approach

The
recovery and reuse of costly nanocatalysts is an essential
operation in modern nanocatalysis, and improvements in catalyst reusability
can contribute significantly to the economic viability and sustainable
development of nanocatalysis. Herein, starting with the application
of a silicone nanofilament (SNF) coating on a target substrate, a
mussel-inspired approach in the form of polydopamine (PDA) deposition
on the SNF surface was used to form in situ-reduced Pd nanoparticles
(Pd NPs) and to stabilize them on the SNFs. This PDA-mediated approach
enabled a high integrity nanocatalyst system to be built on a free-standing
SNF support while retaining the porosity in the original SNF architecture.
The SNFs-Pd nanocomposites prepared as such were applied to the inside
walls of laboratory chemical reactors and used as recycling-free nanocatalyst
systems for Pd-catalyzed organic reactions without the laborious conventional
catalyst recovery and redispersion processes. The SNFs-Pd catalyst
system exhibited high activity and high selectivity in single and
successive Heck coupling reactions; and a reusability as high as 90%
was still possible in the 20th cycle. This mussel-inspired approach
is highly versatile and can be applied to laboratory chemical reactors
in different shapes, sizes, and configurations to scale up the nanocatalyst
applications. Furthermore, the general utility of the chemistry involved
allows this surface modification technique to apply to other supported
noble metal (e.g., Ag, Au, and Pt) catalysts, thereby increasing the
usability and the performance of nanocatalyst systems.