In the present study, the in-situ synthesis of CNTs on carbon paper (CNT/CP), to be used as electrocatalyst support at PEM fuel cell, was experimentally studied with the aim of investigating the role of hydrogen gas. In this regard, the microstructural characterization along with TGA analysis revealed that the structure of the CNTs and the density of defects are highly affected by the absence or presence of hydrogen gas during the synthesis process. According to the experiments, an optimal flow ratio of Ar/H2/C2H2: 200/30/20 was obtained for the synthesis of CNTs on CP impregnated in nickel catalyst. The unique CNT/CP structure presents high specific surface area (159.24 m2/g), large water droplet contact angle (157/2 ± 0.3°) indicating superhydrophobicity, and high hydrophobic stability, therefore, they can be considered as a promising candidate for many technological applications. In this work, CNT/CP was used for supported Pt/Fe/Ni catalysts as PEM fuel cell cathode. The results of the Half-cell testing showed that not only the application of CNTs instead of carbon black has a particular role in the performance improvement of the polymer fuel cathode but also the presence of hydrogen gas in the metal catalyst reduction stage significantly improves the efficiency to 91%. Considering that the high efficiency was achieved without the requirement of excess catalysts loading and the corresponding additional expenses in PEMFCs.
