Graphite oxide as an efficient and robust support for Pt nanoparticles in electrocatalytic methanol oxidation

Abstract

Pt nanoparticles were encapsulated in graphite oxide (GTO) and used as electrocatalysts for methanol oxidation. When compared with Pt nanoparticles composited with graphene oxide (GO/Pt), Pt nanoparticles sandwiched between the graphene layers of a GTO framework (GTO/Pt) showed significantly improved electrocatalytic performance and stability for methanol oxidation. The simultaneous reduction of Pt4+ and oxygen moieties of GTO during the synthesis of GTO/Pt resulted in a composite with moderately stacked graphene layers. This structure enhanced the kinetic feasibility of methanol oxidation with no decrease in the active surface area of Pt nanoparticles, and also increased the tolerance for the adsorption of surface-adsorbed intermediates. In addition, in contrast to the GO/Pt composite, the Pt nanoparticles in GTO/Pt did not aggregate during the electrochemical reaction, which was responsible for the superior long-term stability of the GTO/Pt. Thermal reduction of GTO/Pt (rGTO/Pt) resulted in rather inferior electrocatalytic responses due to a decrease in the accessible surface area of Pt nanoparticles in the densely stacked graphene layers. Therefore, other than a synthetic convenience (GTO does not require a mechanical exfoliation step.), this work suggests that the use of GTO rather than GO as a support could be a more efficient tactic in preparing graphene composites when the electrochemical reaction on the surface of impregnated nanoparticles is important.