Highly efficient iron–nitrogen electrocatalyst derived from covalent organic polymer for oxygen reduction

Abstract

Developing non-precious metal catalyst with high activity, good stability and low cost for electrocatalytic oxygen reduction reaction (ORR) is critical for the wide application of energy conversion system. Here, we developed a cost–effective synthetic strategy via silica assistance to obtain a novel Fe3C/Fe–Nx–C (named as COPBP-PB-Fe-900-SiO2) catalyst with effective active sites of Fe–Nx and Fe3C from the rational design two-dimensional covalent organic polymer (COPBP-PB). The nitrogen-rich COP effectively promotes the formation of active Fe–Nx sites. Additionally, the silica not only can effectively suppress the formation of large Fe-based particles in the catalysts, but also increases the degree of carbonization of the catalyst. The as-prepared COPBP-PB-Fe-900-SiO2 catalyst exhibits high electrocatalytic activity for ORR with a half-wave potential of 0.85 V vs. reversible hydrogen electrode (RHE), showing comparable activity as compared with the commercial Pt/C catalysts in alkaline media. Moreover, this catalyst also shows a high stability with a nearly constant onset potential and half-wave potential after 10,000 cycles. The present work is highly meaningful for developing ORR electrocatalysts toward wide applications.