Au/reduced graphene oxide composites: eco-friendly preparation method and catalytic applications for formic acid dehydrogenation

Abstract

This paper presents a new, simple, accessible and environmentally friendly method to prepare gold-reduced graphene oxide composites (Au/rGO) with gold concentration of 2.5 wt%, 5 wt% and 10 wt%. The Au/rGO materials with low Au concentration present AuNPs of low dimensions and proved good catalytic activity for formic acid (FA) decomposition in aqueous solution. The most of the structural characteristics are not dependent of the gold content such as: large surface area (234–278 m2 g−1), good crystallinity of graphenes, few layers of carbon in the graphene support (5–6 layers), medium density of structural defects in graphene, the presence of remanent oxygenated groups on the graphene surface, very good dispersion of AuNPs on both sides of the graphene sheets. The AuNPs size instead is strongly dependent on the Au concentration: The smallest nanoparticles were obtained for Au2.5/rGO (3–5 nm) and the largest for Au10/rGO (10–14 nm). The position of the energy levels (conduction band and valence band) relative to the Fermi level also changes with the Au content.