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

• Published in: Applied surface science 2022-02, Vol.575, p.151729, Article 151729
• Main Authors: Lee, Dong-Eun, Moru, Satyanarayana, Jo, Wan-Kuen, Tonda, Surendar
• Format: Article
• Language: English
• Subjects: Bimetallic catalyst; Bioinspired; Electrocatalysis; Overall water splitting; Vitamin B12
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2021.151729

[Display omitted] •Bioinspired vitamin B12 (VB12)-based bifunctional electrocatalyst was developed.•VB12 was engineered to add Fe–Nx active sites to the pre-existing Co–N4 sites.•The cell voltage required for water splitting was found to be ∼1.65 V at 10 mA cm−2.•The catalyst displayed high stability and durability during prolonged test cycles.•Efficient Co–N4/Fe–Nx active sites and systematic synthesis contributed to the high catalytic activity.•The HER and OER activities of the catalyst outperformed those of previous reports. 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–Nx 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–Nx 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.