Fluorine-doped PBA@FPO core-shell structure as bifunctional electrocatalyst for overall water splitting through electronic engineering synergy

This work successfully synthesized and empirically evaluated the F-doped Prussian blue analogues (PBA) deposition of FePO 4 (FPO) on the nickel foam (NF). The PBA/NF cubic structure was hydrothermally grown on the Ni-MOF/NF precursor and encapsulated by electrodeposited FePO 4 spheres, leading to the final F-PBA@FPO/NF. The catalyst serves as a high-performance bifunctional electrocatalyst, delivering low overpotentials of 220 mV for the OER and 174 mV for the HER at 10mA cm −2 , coupled with favorable Tafel slopes of 144 and 130.9 mV dec −1 , respectively. The catalyst was doped with a large number of F atoms, which formed abundant hydrogen bonds with water, thereby promoting the generation of HER. The substantial formation of Ni-F bonds during the testing stage created a modified local coordination environment, thereby establishing a foundation for the continuous in-situ formation of active NiOOH phases under operating conditions. Interestingly, F doping plays a dual role: it tailors the electronic structure of metal centers and induces in-situ etching of the material, thereby generating structural openings during the electrochemical process. This work advances the fundamental understanding and rational design of F-doped catalysts and bifunctional electrocatalysts for hydrogen production.