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

Abstract

FeN4 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 FeN4 single-atom catalysts is highly dependent on the density and distance of the FeN4 active centers. However, controllable synthesis of FeN4 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 FeN4 active centers. The influence of the nature of the nitrogen groups in the precursors on the number of FeN4 active sites and the ORR activity trend of the obtained FeN4–C catalysts was investigated. The catalyst with the highest density of FeN4 sites showed a high efficiency for ORR, making its application in Zn-air batteries promising.