Soluble conjugated polymer enriched with pyridinic nitrogen atoms and its application as high-performance catalyst for oxygen reduction

A novel composite formed between nitrogen-rich soluble conjugated polymer and carbon was prepared and evaluated as a candidate for oxygen reduction reaction (ORR) catalyst, and the composite was designated as PBBDP/C. The complexation between copper ion (II) and PBBDP/C formed another catalyst, named Cu-PBBDP/C. Electrochemical tests including cyclic voltammetry (CV), linear sweep voltammetry (LSV), and rotating ring disk electrode (RRDE) were used for the characterization of the ORR activities of the catalysts. The measurements showed that both of the catalysts showed considerable stability and apparent ORR activities, and the ORR activity of Cu-PBBDP/C was much higher than that of PBBDP/C. For digging into the exact ORR mechanisms, the rate constants of possible ORR pathways were calculated as analyzed for both catalysts. For PBBDP/C catalyst, the result indicated that oxygen was reduced through two parallel routes, the four-electron pathway and the two-electron pathway taking H2O2 as the intermediate product. For Cu-PBBDP/C catalyst, the ORR was via a four-electron transfer-dominant process. In this case, the Cu-N (x) group is active sites for the direct reduction of oxygen to water.