Interface synergistic-driven electronic modulation in amorphous CoFeB@g-C₃N₄ for high-performance bifunctional OER/HER electrocatalysis

To meet the ever-increasing global energy demand, the development of economical and environment friendly energy sources is essential. Therefore, designing efficient and robust electrocatalysts is crucial to enhance HER and OER performance in electrocatalytic water splitting. Herein, a chemical reduction technique was used to prepare cobalt/iron boride nanoparticles (CoFeB NPs) and their heterojunction with nanosheets of graphitic carbon nitride (CoFeB@g-C₃N₄), which were then used as a bifunctional HER/OER electrocatalyst. The electrochemical results demonstrated that the low overpotentials of 282 mV for the oxygen evolution reaction (OER) and 66 mV for the hydrogen evolution reaction (HER) were required to achieve a current density of 10 mA cm⁻¹ in 1.0 M KOH electrolyte, with corresponding Tafel slope values of 48 and 85 mV dec⁻¹, respectively. Moreover, post-OER analysis demonstrates that CoFeB@g-C₃N₄ maintains its morphology and structural endurance without a significant change for 72 h. DFT simulations verified that the CoFeB@g-C₃N₄ heterojunction lowers the Gibbs free energy for HER and OER, making both reactions thermodynamically favorable, with the Fe-site identified as the most active. Owning to its high catalytic activity, low cost, and simple preparation, the CoFeB@g-C₃N₄ heterojunction emerges as a promising candidate for electrochemical water splitting and storage.