Facile synthesis of polydopamine-functionalized hollow graphene composite microspheres and their application in methanol oxidation reaction

[Display omitted] •A novel PDA/CG microsphere with three-dimensional porous spherical architecture was prepared.•CG microspheres with PDA functionalized possess a uniform dispersion of ultrafine Pt NPs and improved hydrophilicity.•Pt/PDA/CG catalyst has a conductive network and internal void to facilitate the proton transmission and electrolyte fluidity.•Pt/PDA/CG catalyst exhibits excellent catalytic activity for methanol oxidation reaction. In this study, a novel polydopamine (PDA) coating graphene oxide (CG) microsphere (named as PDA/CG) is successfully synthesized and characterized. Graphene oxide (GO) is used as base structural material and carbon black nanoparticles (CB) act as spacers to form the hollow microsphere, which can also prevent the re-stacking of graphene and facilitate the formation and stability of spherical structures. The as-prepared PDA/CG provides high electrical conductivity, good hydrophilic microenvironment and functional nitrogen contained groups, which are beneficial to obtain ultrafine platinum nanoparticles (Pt NPs), stabilize Pt NPs and enhance the electrocatalytic performance of Pt-based electrocatalysts. As for the methanol oxidation reaction (MOR), the microstructure of Pt/PDA/CG provides a suitable microspace to facilitate the reactor agent transport, proton transmission and electrolyte fluidity. Pt/PDA/CG exhibits excellent electrocatalytic activity (2120 mA mgPt−1) toward MOR.