One-pot synthesis of porous monolith-supported gold nanoparticles as an effective recyclable catalyst

Gold nanoparticles (AuNPs) are excellent catalysts, but their recycling remains a central concern. Support of AuNPs on a porous monolith is one popular strategy but it usually suffers from multistep and inefficient preparation. Herein, we show a one-pot strategy to recyclable AuNPs supported on a porous monolith. It is known that the polymerization of the oil phase of a high internal phase emulsion (HIPE), stabilized by surfactants, can lead to a macroscopic and porous monolith (polyHIPE). If the surfactant is replaced with a dendritic amphiphile (DA) of PEI@PS (hyperbranched polyethylenimine (PEI) functionalized with polystyrene (PS) and dodecyls), and the water phase is charged with chloroauric acid, then the one-pot fabrication of AuNP-decorated polyHIPE (Au-DA-polyHIPE) is feasible. Alternatively, if Au-DA (AuNP stabilized with PEI@PS) is used instead of the surfactants, then Au-DA-polyHIPE can be similarly obtained. The Au-DA-polyHIPE samples have open-cell and porous structure, and can effectively catalyze the reduction of 4-nitrophenol. The catalytic materials are recyclable without any decrease in activity, at least within 6 cycles, in which the multivalent and multi-ligand PEI should be responsible for the stability.