**4. Conclusions**

In order to improve the activity and stability of PEMFC catalysts it is necessary to explore more stable catalyst for ORR. Iodine doped graphene was prepared and tested as ORR catalyst. The preparation is seen as overall process as facile, does not require complicated steps and is appropriate for scaling up. The surface compositions of I-doped graphene were analyzed by XPS. The XPS spectra of the most prominent transitions of the chemical elements were obtained: C1s, O1s, I3d 5/2, which indicated that iodine had been successfully binded on the surfaces of graphene. The chemical stability of I-doped graphene was tested in order to assess long-term performance. Insightful information on the distribution and uniformity of phenomena that are taking place inside a fuel cell are obtained from the CFD model used to analyze how this electrochemical device performs locally. The numerical results for two cases investigated (Pt/C with ECSA 35 m<sup>2</sup> /g and I-doped graphene with ECSA 85 m<sup>2</sup> /g) are validated by experimental data and a good agreement between modeling and experimental data were found. An overall 20% increase in current density was obtained while increasing the electrochemically active surface area (ECSA). The experimental results provide a simple route to synthesize I-doped graphene with potential application for advanced energy storage, as well as useful information to design new graphene base materials. In conclusion, we have designed a novel hybrid structure with enhanced electrochemical performances. The power output can be attributed to synergistic effects from graphene and iodine providing high utilization of Pt and better mass transport in the catalyst layer.

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