| Full cell is generally believed to be an important part among various new energy resources with the rapid energy consumption. Pt/C has been extensively applied in cathodes of full cells, the emerging progress of which, however, is seriously restricted by the poor durability, cross effect of methanol, carbon monoxide poisoning of Pt/C.Herein, much effort should be devoted towards the development of new non-noble metal catalysts that can replace Pt/C.At present, non-noble metal doped porous carbon materials (M-N-C) has become a hot topic by virtue of their excellent specific surface area, porous structure, active sites with large density which are formed by heteroatom doping, thus presenting favorable catalytic performance, durability and methanol tolerance. In the present work,hollow-nanostructured non-noble metal catalyst doped with heteroatom which further demonstrates high catalytic performance is successfully synthesized, followed by the investigation of electrocatalytic performance, the details are shown as follows:1. A new "reactive hard template" method has been employed to fabricate mesoporous Fe-N-C catalyst with hollow spindle structure, in which nitrogen doped graphitic carbon is embedded in spindle Fe-N-C carbon layer. In terms of the synthesis method, it is found that core spindle Fe2O3 not only offers spindle structure for the catalyst but also provides Fe source for the catalyst to generate Fe3C nanoparticles.PDA shell which acts as metal ion (Fe3+) of the catalyst can facilitate the decomposition of polymer into carbon species, thus promoting the deposition of Fe3C during decomposition. Thanks to the facilitation effect on active sites of FeCC nanoparticles in graphitic carbon layer and Fe-N, species in high mesoporous hollow structure, the half-wave potential, electron transfer number and hydrogen peroxide yield are in close proximity to that of commercialized PtUC. Additionally, the durability,together with the methanol tolerance of the studied sample has been demonstrated to be superior than that of commercialized Pt/C.2. The "active hard template" method is again employed. Specifically, the as-chelated dopamine and Fe3+ are coated on the surface of cobalt sphere which acts as template, hollow carbon sphere structure with iron and cobalt co-doping can be achieved after high-temperature annealing and acid treatment. During the preparation process, the cobalt sphere template provides cobalt ion and simultaneously the sphere structure for (Fe,Co)-N-C catalyst, thus contributing to large specific surface area, that is, increasing the contact area between active sites and electrolyte. The co-doping of iron and cobalt is favorable for the acquisition of active sites with large density in the the (Fe,Co)-N-C catalyst. Additionally, the formation of carbon after dopamine annealing enables the reduction of cobalt ion into cobalt particles, which are then embedded in carbon layer, the cobalt particles present higher active center than carbon,by virtue of which ORR electron transfer becomes more feasible. The test result show that the half-wave potential is in close proximity to that of Pt/C, thereby indicating excellent electrocatalytic performance. |
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