Tuning morphology and structure of Fe–N–C catalyst for ultra-high oxygen reduction reaction activity.

Exploring efficient and durable non-precious metal catalysts for oxygen reduction reaction (ORR) has long been pursued in the field of metal-air batteries, fuel cells, and solar cells. Rational design and controllable synthesis of desirable catalysts are still a great challenge. In this work, a novel approach is developed to tune the morphologies and structures of Fe–N–C catalysts in combination with the dual nitrogen-containing carbon precursors and the gas-foaming agent. The tailored Fe–N 1 /N 2 –C-A catalyst presents gauze-like porous nanosheets with uniformly dispersed tiny nanoparticles. Such architectures exhibit abundant Fe-N x active sites and high-exposure surfaces. The Fe–N 1 /N 2 –C-A catalyst shows extremely high half-wave potential (E 1/2 , 0.916 V vs. RHE) and large limiting current density (6.3 mA cm−2), far beyond 20 wt% Pt/C catalyst for ORR. This work provides a facile morphological and structural regulation to increase the number and exposure of Fe-N x active sites. The tailored Fe–N–C catalyst presents plentiful Fe-N x active sites and highly exposed active surfaces, resulting in an ultra-high ORR activity far beyond the 20 wt% Pt/C catalyst. Image 1 • A novel approach is explored to tune morphology and structure of Fe–N–C catalyst. • The tailored catalyst presents abundant active sites and high exposure surfaces. • The catalyst shows ultrahigh ORR activity, far beyond the commercial Pt/C. [ABSTRACT FROM AUTHOR]