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-N-4 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-N-4 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 similar to 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.

Automated summary

This study demonstrates remarkable electrocatalytic water-splitting activity in alkaline media by employing a bioinspired, noble-metal-free vitamin B12 catalyst on a conductive graphene substrate. The optimized catalyst shows outstanding performance with high density of active sites, resulting in only 120 and 300 mV overpotentials at 10 mA cm(-2) for hydrogen and oxygen evolution reactions, respectively, while maintaining stability and durability over a 20-hour period.