Nitrogen Doped Reduced Electrochemically Exfoliated Graphene Oxide Inserted Carbon Black As Novel Catalyst Support for the Hydrogen Fuel Cell
Authors: Ji Zhaoqi , Perez-Page Maria , Chen Jianuo , Holmes Stuart 
Published: December 2020

Graphene, a two-dimensional (2D) structure of honeycomb lattice material with long-range π-conjugation, is an ideal catalyst support material due to its large surface area, excellent electrical conductivity, good mechanical and electrochemical stability [1]. It has already been reported that platinum nanoparticles (PtNPs) supported on reduced graphene oxide (rGO), is limited by van der Waals force resulting in the restacked rGO flakes during the reduction process, thereby hindering the transport of fuel gas to approach Pt active sites [2, 3].
To overcome this issue, several publications have successfully developed PtNPs catalyst supported on rGO and carbon black (CB) hybrid supporting materials [4]. The synergistic effect between rGO and CB could enhance its activity for oxygen reduction reaction through controlling PtNPs size as well as improve its durability by preventing the agglomeration and corrosion of supporting materials [3]. However, Hummers GO leads to environmental and safety issues (use KMnO4, strong oxidizing agents and concentrated H2SO4) as well as a long-time preparation with high cost [2].
Our previous research has already developed a novel graphene-based material prepared by electrochemical exfoliation of graphite, which is faster, more environmentally friendly and has a high yield, intercalated by CB as a bi-support and achieved 50% improvement performance compared with Pt/CB.
To further improve catalyst activity, some research proposed that the introduction of nitrogen, especially graphitic N and pyridinic N, on the surface of carbon materials could improve ORR activity and electronic conductivity by changing the local electronic structure as well as polarization of the graphene network with smaller energy band gap [3, 5]. However, the effect and comparation of nitrogen doped rEGO intercalated by CB (NrEGO-CB) and nitrogen doped both EGO and CB (NrEGO-NCB) as bi-support materials to improve the performance of the hydrogen fuel cell have not been studied.
In this work, EGO and EGO-CB was doped with nitrogen by hydrothermal treatment with urea as a nitrogen precursor in a Teflon-steel autoclave. Pt catalysts were synthesized by a modified polyol reduction method. Successful preliminary results can be observed in Fig 1, which shows that PtNPs supported on NrEGO-CB with ratio of 2 to 3 has a maximum power density of 1.2 W cm-2. It is more than 4 times compared with that 0.3 W cm-2 of Pt/CB.

References

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Figure 1