Metal- and non-metal-incorporated vitamin B₁₂ on graphene as a bio-derived electrocatalyst for the high-performance oxygen reduction reaction in acidic media

The development of fine-tuned non-platinum group metals and their derivatives, which are high-performance, economical, and stable electrocatalysts used for the oxygen reduction reaction (ORR), is critical for the large-scale deployment of fuel cells and metal–air batteries. This study presents a novel strategy that uses vitamin B₁₂ (VB) as a bioinspired resource for the ORR; VB was modified using metal and non-metal incorporation to boost the efficiency of the ORR. The chemical structure of VB on a graphene substrate was tailored by synergistically incorporating both iron and sulfur upon pyrolysis, yielding various active sites based on Fe–(N,S)–C and Co–(N,S)–C. The resultant catalysts, termed Fe–SVB/GR, exhibit prominent electrocatalytic performance for the ORR via a favorable 4e^– reaction pathway. The onset and half-wave potentials of the optimized electrocatalyst were 0.90 and 0.74 V vs. reversible hydrogen electrode, respectively, which are comparable or better than those previously reported for non-platinum group catalysts. The Fe–SVB/GR electrocatalyst developed in this study outperformed a commercial Pt/C catalyst in terms of its durability and methanol tolerance. Therefore, this study introduced a novel strategy to produce bio-derived materials as non-platinum group electrocatalysts used as efficient cathode materials in energy-conversion devices.