Bio-inspired chitosan-heme-vitamin B 12 -derived Fe-Co bimetallic-doped mesoporous carbons for efficiently electro-activating oxygen.

A bio-inspired bimetallic Fe- and Co-doped nitrogen-carbon material (Fe-Co-N-C) was synthesized using chitosan and porphyrin-like heme and vitamin B12 precursors. Anionic heme with Fe-N4 moieties and vitamin B12 with Co-N4 moieties were grafted onto the surface of acidic chitosan polymers through interactions with cationic -NH3+, and these polymers were coated onto nano-sized silica spheres to form the composite precursors. The optimised thermolysis of these composites yielded mesoporous carbons with abundant surface Fe-Nx and Co-Nx sites. The as-prepared Fe-Co-N-Cs catalyzed the oxygen reduction reaction (ORR) in both alkaline and acidic conditions. It not only provided a low-cost bio-inspired synthesis for bimetal-doped carbons using biologics with the definitive molecular structure but also the as-prepared mesoporous Fe-Co-N-Cs represented as the possible NPMC candidates for replacing Pt-based electrocatalysts in fuel cells.