Synthesis of poly(2,6-diaminopyridine) using a rotating packed bed toward efficient production of polypyrrole-derived electrocatalysts

Synthesis of pyridinic nitrogen-rich polymers is a key step in obtaining high-performance polypyrrole-derived electrocatalysts for the oxygen reduction reaction. A straightforward and controllable synthesis method is highly favored to efficiently manipulate the structural and electronic properties of polypyrrole-derived electrocatalysts. Herein, the strategy for the preparation of poly(2,6-diaminopyridine) (PDAP) is developed with the assistance of an external circulation rotating packed bed (EC-RPB). The polymerization could be divided into two stages: a kinetically fast stage and a rate-determining phase-transfer stage. By using the EC-RPB, the polymerization is sufficiently reduced to 3 h with a conversion rate of over 90% achieved due to accelerated mass transfer in the second stage, exhibiting significant improvement in the common processing for PDAP (∼87% in 12 h). Furthermore, with co-doped iron and manganese species, the obtained catalyst shows a good ORR activity and stability, with up to 0.881 V of half-wave potential in an alkaline environment and 0.718 V in an acid environment. This work proposes a facile and efficient synthesis method for PDAP which could also be extended to the production of other polypyridine-derived electrocatalysts.