Abstract:
Biomass-derived carbon materials exhibit great potential in the field of electrocatalytic water splitting due to their unique morphologies, high specific surface areas, and hierarchical porous structures. Nevertheless, inherent drawbacks of biomass-derived carbon materials, such as a relatively low density of active sites and inferior structural stability, severely hamper their practical application potential and significantly limit the realization of their full value in real-world scenarios. In this study, biochar (BC) was formed by subjecting disposable chopsticks to high-pressure hydrothermal carbonization. Subsequently, iron (Fe) was further modified on its surface through an impregnation and heat treatment process, resulting in the construction of a Fe@BC composite catalyst with interfacial synergistic effects. Moreover, the electrocatalytic oxygen evolution reaction (OER) performance of this catalyst was investigated. The study found that iron (Fe) was distributed on the surface of the BC support in the form of oxides. Moreover, with the introduction of Fe, the crystal phase and morphological structure of BC were altered, leading to the formation of a porous lamellar structure. Importantly, the strong Fe-O interfacial interaction formed between BC and Fe atoms can induce the generation of dual active centers of Fe
2+ and Fe
3+. As the oxygen evolution reaction (OER) proceeds, more defective hydroxyl oxide species are formed on the surface of the catalyst, which effectively promotes the redistribution of electrons and replenishes the charge accumulation at the Fe sites during the OER process. As a result, the catalytic performance of the active centers of Fe
2+ and Fe
3+ is significantly enhanced and stabilized. This catalyst exhibits excellent OER catalytic performance in an alkaline medium. Under the conditions of a current density of 10 mA/cm
2 and 200 mA/cm
2, its potentials relative to the reversible hydrogen electrode are 1.482 V and 1.550 V respectively, which are significantly superior to those of the commercial RuO
2 catalyst. In addition, the performance of this catalyst can be stably maintained for more than 48 hours. The research findings provide innovative ideas for the design of a new type of highly efficient OER catalytic system coupling biochar with transition metals.