科研之友
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摘要
The efficient and low-cost platinum group metal (PGM)-free metal-nitrogen-carbon electrocatalysts (M-N-C) are potential alternatives for the oxygen reduction reaction (ORR) in artificial energy conversion devices. However, the solid-state reactions of M/C/N-containing precursors at high temperature was rather complicated, making the engineering of carbonization processes of M-N-C catalysts challenging and less explored. Herein, we report a way to modulate the pyrolysis processes of M-N-C by pre-organization of the molecular precursors via a simple solvation, in which, the simultaneous hydrogen bonding and coordination interactions played an important roles. It was revealed that the supramolecular precursors from different solvents had the same chemical compositions but quite different crystal structures. Accordingly, the pyrolysis processes were greatly altered, making the as-prepared Co-N-C exhibit distinct morphologies ranging from worm-nanotubes to bamboo-nanotubes and to porous nanosheets. The optimized Co-N-C showed competitive bifunctional electrocatalytic ORR and OER activities, which were further successfully applied to advance the rechargeable Zn-air batteries with excellent cycling stability over 600 h at a current density of 20 mA cm(-2) and voltage gap (0.76 V). This work highlights the great potential of the pre-organization for the designing and selecting of precursors to engineer pyrolyzed M-N-C with higher electrocatalytic activities.
- 出版日期2019-4
- 单位东南大学
