▎ 摘　　要

Nitrogen doping carbon nanomaterial has become an important metal-free electrocatalyst for oxygen reduction reaction (ORR) in fue cells. N-doped graphene quantum dots (N-GQDs) are one of the most promising nanomaterials due to abundant electrocatalytic edging and N doping active sites, but low yield, high dispersity and no forming efficient percolative conductive network hinder their direct application as the electrocatalyst. Hydrothermal method is an effective route for preparing high-quality N-GQDs and meanwhile, overcomes the drawbacks of complicated preparing progress and low yield. We further hydrothermally prepare the hybrid material of N-GQDs/Graphene (G) to immobilize N-GQDs on graphene and construct 3D conductive network. Therefore, the inexpensive N-GQDs/G integrates the advantages of rich edges, N doping active sites, high conductivity, and large specific surface area. As confirmed by a series of characterizations and tests, the N-GQDs/G performs high electocatalytic performance (dominating four-electron pathway), long-term stability and resistance to methanol crossover. Moreover, we demonstrate that the type of N specie plays an important role in ORR, especially, the pyridinic-N. (C) 2016 Elsevier Ltd. All rights reserved.