Polymer/trimer/metal complex mixtures as precursors of gold nanoparticles: tuning the morphology in the solid-state

Abstract

The pyrolysis of several physical mixtures of AuCl(PPh3) with polymeric [NP(O2C12H8)]n or cyclic N3P3(O2C12H8)3 phosphazenes, formed as solid powders or films with different molar ratios, have been studied under air and at 800 °C. The characterization of the products has shown that the particle size and morphology are strongly dependent on the nature of the phosphazene, the phosphazene/AuCl(PPh3) molar ratio and on the preparation methodology. Gold nanoparticles (NPs) with mean sizes as small as 3.5 nm were obtained from a [NP(O2C12H8)]n/AuCl(PPh3) 1:1 film. The particle morphology was also strongly dependent on the experimentally conditions of the pyrolysis. Powdered materials exhibit a 3-D irregular morphology in the mixture [NP(O2C12H8)]n/AuCl(PPh3) 3:1 film, and gold foams in the 1:1 ratio, both from the [NP(O2C12H8)]n/AuCl(PPh3) as well as N3P3(O2C12H8)3/AuCl(PPh3) mixtures. These results show for the first time the possibility of controlling morphology and size of gold particles obtained by solid-state reactions.