Bioinspired Design of an Immobilization Interface for Highly Stable, Recyclable Nanosized Catalysts

Abstract

Immobilization of nanometer-sized metal catalysts into porous substrates can stabilize the catalysts and allow their recycled uses, while immobilization often sacrifices the active surface of catalysts and degenerates the local microenvironments, resulting in the reduction of the catalytic activity. To maintain a high activity of immobilized nanocatalysts, it is critically important to design an interface that minimizes the contact area and favors reaction chemistry. Here we report on the application of mussel-inspired adhesion chemistry to the formation of catalytic metal nanocrystal-polydopamine hybrid materials that exhibit a high catalytic efficiency during recycled uses. Electrospun polymer nanofibers are used as a template for in situ formation and immobilization of gold nanoparticles via polydopamine-induced reduction of ionic precursors. The prepared hybrid nanostructures exhibit a recyclable catalytic activity for the reduction of 4-nitrophenol with a turnover frequency of 3.2-5.1 μmol g(-1) min(-1). Repeated uses of the hybrid nanostructures do not significantly alter their morphology, indicating the excellent structural stability of the hybrid nanostructures. We expect that the polydopamine chemistry combined with the on-surface synthesis of catalytic nanocrystals is a promising route to the immobilization of various colloidal nanosized catalysts on supporting substrates for long-term catalysis without the physical instability problem.

Palladium on Polydopamine: Its True Potential in Catalytic Transfer Hydrogenations and Heck Coupling Reactions

“…These include Suzukic ouplings and catalytic transferh ydrogenation (CTH) reactions. Although the Suzuki chemistry is well described in terms of reactionc onditions, scope, and limitations, [15,16] in the CTH field the reports follow ac lear pattern:t he assembled metal/PDA (or PDAbased) material containing Au, [17][18][19][20][21][22][23][24][25][26] Ag, [26][27][28] Pd, [29,30] or Pt/Au [31] as metal component is mostly used in as ingle transformation involving 4-nitrophenol, 100-2000 equivalent of NaBH 4…”

Electrospun PCL/keratin/AuNPs mats with the catalytic generation of nitric oxide for potential of vascular tissue engineering

“…Two‐step method to hybrid nanofibrous mats with metal nanoparticles, that is, the first step for mental ion adsorption and the second step for in situ reduction via photosynthesis or reducer, is simple and green . The Au ion was absorbed on PCL/keratin mats and subsequently reduced to nanoparticles by NaBH 4 .…”

“…Recently, Yu group demonstrated that keratins could improve adhesion, proliferation, and viability of porcine adipose‐derived stem cells . Metal ions (e.g., Ag + and Au 3+ ) can be easily bound under the chelating effect and electrostatic attraction by virtue of the abundant free amino and carboxyl groups of keratins . In addition, the formed metal nanoparticles are stable due to the chemical gold–sulfur (Au–S) or silver–sulfur (Ag–S) bonds.…”

“…9 Metal ions (e.g., Ag + and Au 3+ ) can be easily bound under the chelating effect and electrostatic attraction by virtue of the abundant free amino and carboxyl groups of keratins. [10][11][12] In addition, the formed metal nanoparticles are stable due to the chemical gold-sulfur (Au-S) or silversulfur (Ag-S) bonds. Electrospinning has become the most popular technology for the preparation of tissue-engineering scaffolds.…”

Dual-Functional Grafted Electrospun Polymer Microfiber Scaffold Hosted Palladium Nanoparticles for Catalyzing Redox Reactions

“…In general, the methods used for the incorporation of NPs on the electrospun polymer fibers are: (i) direct attachment of noble metal NPs via electrostatic force, hydrogen bonding, or binding through functional groups on NPs, (ii) loading of precursor noble ions through ion‐exchange/complexation with binding sites on the fibers and subsequent in situ chemical reduction, and (iii) hydrothermal assisted methods mostly used for the metal oxide NPs . The different electrospun fibers made up of chitosan/poly(methacrylic acid), poly(ε‐caprolactone) surface functionalized with poly(dopamine), porous carbon nanofibers formed by precursor fibers of poly(styrene)/poly(acrylonitrile) (PAN), polyacrylic acid/polyvinyl alcohol (PVA), polyethyleneimine/PVA, poly( l ‐lactic acid)/amino‐functionalized silsesquioxane, nanoporous PVA mat, carbon nanofibers prepared from electrospun PVA mat, etc., have been used to host metal nanocatalysts for the organic transformations and inorganic reductions. The sulfonic group functionalized PAN fibers have been found to be efficient heterogeneous catalysts for the acetalization and esterification organic reactions .…”