Enhancing the catalytic activity of flowerike Pt nanocrystals using polydopamine functionalized graphene supports for methanol electrooxidation

Abstract

A simple and effective approach was demonstrated to synthesize flowerlike Pt nanocrystals on polydopamine (PDA) functionalized reduced oxide graphene (RGO). Inspired by mussels, the PDA/RGO composites were obtained via the reduction of GO nanosheets by dopamine, followed by simultaneous capping by PDA. Then, the synthesis of Pt flowerlike nanocrystals assembled with small elongated nanoparticles on PDA/RGO (Pt(F)-PDA/RGO) was carried out by mixing H2PtCl6 with PDA/RGO in the presence of ascorbic acid under boiling. PDA as a surface-adherent and multifunctional biopolymer played a dual role: dispersing stable RGO into aqueous solution and providing functional groups to bind metal ions and metal nanoparticles. The as-prepared Pt(F)-PDA/RGO catalyst showed considerably improved catalytic activity and stability toward methanol electrooxidation, compared with Pt nanoclusters on PDA/RGO (Pt(C)-PDA/RGO) and Pt nanoparticles on pristine graphene sheets (Pt/RGO). The kinetic characterization of Pt(F)-PDA/RGO was further discussed by cyclic voltammetry. This simple and green approach could be applicable to other metallic nanocrystals as a novel platform in catalysis, fuel cells and biosensors.