Structurally engineered vitamin B12 on graphene as a bioinspired metal–N–C-based electrocatalyst for effective overall water splitting in alkaline media

The development of a cost-effective, high-performance, and stable electrocatalyst capable of producing clean and renewable hydrogen via water splitting is challenging. This study demonstrates a remarkable electrocatalytic water-splitting activity in alkaline media by employing a bioinspired, noble-metal-free vitamin B12 (VB12) catalyst on a conductive graphene substrate. VB12 could inherently produce unique Co–N₄ active sites upon thermal treatment owing to its Co-centered macrocyclic corrin ring, and VB12 was further engineered to produce additional Fe–N_x sites through the incorporation of Fe as a secondary metal cation. The optimal Fe content in VB12 resulted in a high density of exposed Co–N₄ and Fe–N_x active sites. Consequently, the optimized catalyst, denoted as Fe–VB12-2@GR, demonstrated outstanding bifunctional electrocatalytic performance, with overpotentials of only 120 and 300 mV at 10 mA cm⁻² for the hydrogen and oxygen evolution reactions, respectively, while maintaining high stability and durability over a period of 20 h. The cell voltage required for water splitting was calculated as ∼1.65 V at 10 mA cm⁻². This work demonstrates a state-of-the-art design of a bioinspired catalyst for water electrolysis, and thus, we believe that this work has the potential to bring considerable advancements in clean and renewable energy technologies.