Defect engineering of Fe–N doped crumpled graphene for improved ORR performance

As a promising alternative electrocatalyst to platinum for the oxygen reduction reaction (ORR), an Fe-N/C electrocatalyst with more active sites was designed by using N-doped porous crumpled graphene as carbon precursor. More defects provided by the edges and cavities of the porous crumpled graphene facilitated the anchoring and inhibited the growth of Fe clusters, and hence introduced more active sites. Furthermore, crumpled structure combined with the pores provided abundant mass transfer channels, and the fast kinetics were ensured. Consequently, the porous crumpled graphene-based catalyst showed better ORR activity and good electrochemical stability. The half-wave potential (E_1/2) of porous crumpled graphene-based catalyst was 0.69 ​V vs. RHE, and the current retention rate was above 97% after 20000s. In addition, the influence of different morphologies, degrees of defect, and compositions on the distribution of active sites and ORR performance of Fe-N/C were systematically studied, and the formation mechanism of Fe-N/C was proposed. This study provided valuable insights into designing more effective non-precious metal based electrocatalysts.