▎ 摘　　要

A new and straightforward approach for the synthesis of ultrasmall and monodisperse Pt nanoparticles (NPs) and their controlled assembly on graphene based supports including reduced graphene oxide (rGO), commercial carbon black (VC) and rGO-VC hybrid were reported. These supported NPs were utilized as the electrocatalysts for polymer electrolyte membrane fuel cells (PEMFC). Surfactant-assisted reduction of platinum(II) acetylacetonate in hot organic solution yielded 1.2 nm Pt NPs. These ultrasmall Pt NPs were decorated on rGO, VC and the rGO-VC hybrid by using a simple liquid-phase self-assembly method. In the previous studies on Pt/rGO-VC hybrids, on one hand, Pt NPs were synthesized in situ on support, on the other hand, VC was added to synthesized Pt/rGO, and their fuel cell performance have been rarely shown. In our study, rGO and VC were directly mixed and prepared Pt NPs were assembled on rGO-VC hybrid support. Pt/rGO-VC hybrid electrocatalyst possessed substantially better electrocatalytic activity owing to better utilization of Pt compared to Pt/rGO and Pt/VC. Membrane electrode assemblies based on resultant catalysts were characterized in-situ in PEMFC. A superior PEMFC performance of 857 mW cm(-2) (maximumpower density) was achieved with the hybrid catalyst as compared to Pt NPs supported on rGO or VC. (C) 2018 Elsevier Ltd. All rights reserved.