Robust Polymer-Coated Diamond Supports for Noble-Metal Nanoparticle Catalysts

Much research has been done using polymer and silica particles as support materials for catalytically active noble metal nanoparticles, but these materials have limited stability in organic solvents or under extreme reaction conditions such as high pH. Here we present a robust and versatile composite polymer-diamond support for ultrasmall noble metal nanoparticles combining chemical and mechanical stability of diamond with the chemical versatility of a polymer. By exploiting the rich surface chemistry of nanodiamond and incorporating a reactive thiol–ene polymer, a thinly coated polymer-diamond composite was formed. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) confirmed the presence of the polymer. High resolution scanning transmission electron microscopy (S/TEM) analysis showed that <i>in situ</i> growth of gold, platinum and palladium nanoparticles produced high density coverage at the polymer-diamond support surface. Energy dispersive spectroscopy mapping and S/TEM imaging indicated spatial alignment of nanoparticles with chemical groups present in the polymer used for particle tethering. The polymer-diamond supported nanoparticles catalyze the NaBH₄ reduction of para-nitrophenol to para-aminophenol and possess better stability than silica supports which dissolve at high pH resulting in nanoparticle aggregation. With the high robustness of the diamond and the ability to tailor the monomer combinations, this polymer-diamond support system may be expanded to a wide range of nanoparticle compositions suitable for various reaction conditions