Oriented Pt Nanoparticles Supported on Few-Layers Graphene as Highly Active Catalyst for Aqueous-Phase Reforming of Ethylene Glycol

Abstract

Pt nanoparticles (NPs) strongly grafted on few layers graphene (G) have been prepared by pyrolysis under inert atmosphere at 900 degrees C of chitosan films (70-120 rim thickness) containing adsorbed H2PtCl6. Preferential orientation of exposed Pt facets was assessed by X-ray diffraction of films having high Pt loading where the 111 and 222 diffraction lines were observed and also by SEM imaging comparing elemental Pt mapping with the image of the 111 oriented particles. Characterization techniques allow determination of the Pt content (from 45 ng to 1 mu g cm(-2), depending on the preparation conditions), particle size distribution (9 +/- 2 nm), and thickness of the films (12-20 nm). Oriented Pt NPs on G exhibit at least 2 orders of magnitude higher catalytic activity for aqueous-phase reforming of ethylene glycol to H-2 and CO2 compared to analogous samples of randomly oriented Pt NPs supported on preformed graphene. Oriented (Pt) over bar /fl-G undergoes deactivation upon reuse, the most probable cause being Pt particle growth, probably due to the presence of high concentrations of carboxylic acids acting as mobilizing agents during the course of the reaction.