Regulating single-atom distance in carbon electrocatalysts for efficient oxygen reduction reaction via conjugated microporous polymer precursors strategy.

FeN 4 single-atom catalysts are among the most promising electrocatalysts for oxygen reduction reaction (ORR), which has important roles in energy conversion systems, such as fuel cells and metal-air batteries. It has been investigated that the activity of FeN 4 single-atom catalysts is highly dependent on the density and distance of the FeN 4 active centers. However, controllable synthesis of FeN 4 single-atom catalysts with designed active center distance and density is still a remaining difficulty. In this work, a series of pyridyl conjugated microporous polymers with varying types of nitrogen are used as precursors to synthesize carbonaceous single-atom ORR catalysts with different amounts of FeN 4 active centers. The influence of the nature of the nitrogen groups in the precursors on the number of FeN 4 active sites and the ORR activity trend of the obtained FeN 4 –C catalysts was investigated. The catalyst with the highest density of FeN 4 sites showed a high efficiency for ORR, making its application in Zn-air batteries promising. FeN 4 –C catalysts with different active site densities are synthesized by a series of pyridyl conjugated microporous polymers with different amount and position of N as precursors. The FeN 4 –C single-atom catalysts carbonized from polymeric precursors show increasing ORR activity with the increasing of active site density. The optimized FeN 4 –C-4 catalysts with the highest density of FeN 4 active sites show superior ORR performance than Pt/C and having potential for applications in Zn-air battery. [Display omitted] [ABSTRACT FROM AUTHOR]