Nitrogen Doped Graphene-Carbon Nanotubes and Nitrogen Doped Nano-Onion Hybrids As High-Performance Catalysts for Oxygen Reduction Reaction

Abstract

A nitrogen doped nanoonion and nitrogen doped graphene-carbon nanotube hybrid (NNO/NG-NCNT) was prepared as a non-precious electrocatalytic material for oxygen reduction reaction (ORR). The nitrogen doped nanooion (NNO) is a new promising carbon-based catalytic material, and its electrocatalytic activity toward ORR was further improved by mixing with nitrogen doped graphene-CNT (NG-NCNT). This improvement was achieved through the formation of hybrid structure, because the NG-NCNT weakened aggregation of the NNO by working as spacers. The formation of the NNO/NG-NCNT was characterized by Raman spectroscopy, field emission scanning electron microscopy, high resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The ORR performance of the NNO/NG-NCNT was studied using rotating disk electrode (RDE) measurement. The RDE results indicated that the NNO had higher ORR activity than that of NG/NCNT, and the NNO/NG-NCNT showed superior ORR performance which was comparable to that of the platinum-based catalyst. In addition, the NNO/NG-NCNT has excellent long-term durability and tolerance to methanol crossover effect. Thus, the high electrocatalytic activity and good stability of the NNO/NG-NCNT make its potential applications as a metal-free catalyst for ORR.