Breaking the barriers: Engineering the crystalline-amorphous interface of Fe3O4@Fe electrode material for unparalleled energy storage and water splitting efficiency.

Innovatively regulating the crystalline-amorphous (c-a) interface of electrode materials is critical for enhancing supercapacitor and electrochemical water splitting performance. In this research, an oxygen defect-rich Fe 3 O 4 @Fe electrode material with a unique and tunable c-a interface was synthesized using prussian blue (PB) as a template. The resulting interface facilitates electron transport and ion diffusion, increases the charge storage active sites, and enhances energy storage capacity. Density functional theory (DFT) simulations demonstrated that oxygen defects can effectively enhance ionic conductivity and facilitate electrochemical water splitting. The optimal Fe 3 O 4 @Fe electrode exhibits remarkable specific capacitance (1526.766 mF cm−2 at 1 mA cm−2) and exceptional oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance, with overpotential values of 231 and 359 mV at 10 mA cm−2, respectively. Furthermore, as an overall water splitting electrocatalyst, the optimal Fe 3 O 4 @Fe can reach 10 mA cm−2 at a battery voltage of 1.645 V, demonstrating its tremendous potential as a highly efficient electrocatalyst. The oxygen defect-rich Fe 3 O 4 @Fe electrode materials with unique c-a interface are a kind of highly efficient multifunctional electrode material for supercapacitors and overall water splitting. [Display omitted] • The tunable c-a interface enhances electron transport, ion diffusion, and energy storage capability. • Introduction of oxygen vacancies improves electron transfer kinetics and electrochemically active area. • The unique synergistic interaction between the c-a interface and oxygen vacancies enhances rate performance. [ABSTRACT FROM AUTHOR]