Fe3O4@N-Doped Interconnected Hierarchical Porous Carbon and Its 3D Integrated Electrode for Oxygen Reduction in Acidic Media.

The rational design of electrode structure with catalysts adequately utilized is of vital importance for future fuel cells. Herein, a novel 3D oriented wholly integrated electrode comprising core-shell Fe3O4@N-doped-C (Fe3O4@NC) nanoparticles embedded into N-doped ordered interconnected hierarchical porous carbon (denoted as Fe3O4@NC/NHPC) is developed for the oxygen reduction reaction (ORR). The as-prepared catalyst possesses novel structure and efficient active sites. In rotating disk electrode measurements, the Fe3O4@NC/NHPC exhibits almost identical ORR electrocatalytic activity, superior durability, and much better methanol tolerance compared with the commercial Pt/C in acidic media. To the authors' knowledge, this is among the best non-precious-metal ORR catalysts reported so far. Importantly, the Fe3O4@NC/NHPC is successfully in situ assembled onto carbon paper by the electrophoresis method to obtain a well-designed 3D-ordered electrode. With improved mass transfer and maximized active sites for ORR, the 3D-oriented wholly integrated electrode shows superior performance to the one fabricated by the traditional method.