Engineered architecture of nitrogenous graphene encapsulating porous carbon with nano-channel reactors enhancing the PEM fuel cell performance. (December 2017) - Fu, Xiaogang
Abstract: Nanoscale architecturing of platinum group metal-free (PGM-free) electrocatalysts is expected to dramatically improve the overall catalytic performance for oxygen reduction reaction (ORR). Desired structures and morphologies for boosting active site density and enhancing mass and charge transfer are essential for developing next-generation PGM-free electrocatalysts. Herein, we report the design of a M-N-C type catalyst consisting of 3-dimensional graphitic meso-porous carbon spheres wrapped with 2-dimensional graphenized sheets. This heterostructure comprises resultant large electroactive surface area, abundant pore channels, and tuned chemical structures, which provide improved electrocatalytic performance. Meanwhile, these pore structures can be regarded as nano-channel reactors to catalyze ORR with easily accessible active sites, effective mass transfer, and smooth charge transfer. The obtained catalyst delivers a high maximum power density of 0.83 W cm −2 in a single H2 –O2 fuel cell measurement, ranking it as one of the most promising PGM-free catalysts in proton exchange membrane fuel cells (PEMFCs). Moreover, reasonable fuel cell stability was also observed through accelerated degradation testing. This work provides a new avenue for PGM-free catalysts design that can be a step towards practical commercial of PEMFCs. Graphical abstract: Engineered architecture with nano-channel reactors are constructed by wrapping graphenized sheets on graphitic meso-porous carbon spheres. This heterostructures with large electroactive surface area, abundant pore channels, and tuned chemical structures impart improved fuel cell performance by providing easily accessible active sites, effective mass transfer, and smooth charge transfer. Highlights: In-situ graphene encapsulating porous carbon spheres as Fe-N-C based ORR catalysts. Nano-channel reactors in MCS-based catalyst improve the ORR performance. The MCS catalyst delivers impressive activity, stability and durability in fuel cell.