CeO2 facilitates electron transfer at the Fe-Ni2P heterointerface, enhancing the overall process of water splitting

Abstract

This study shows how to create layered nanosheet structures of Fe-doped Ni₂P@CeO₂ on nickel foam using hydrothermal synthesis and low-temperature phosphating for reliable and effective water splitting (HER and OER). The overpotential of the synthesized Fe-Ni₂P@CeO₂/NF is around 63 mV for the hydrogen evolution reaction (HER) and around 180 mV for the oxygen evolution reaction (OER) at a current density of 10 mA cm⁻². Simultaneously, the distinctive stacked nanosheet architecture of Fe-Ni₂P@CeO₂/NF ensures that the catalyst maintains its effectiveness even after prolonged electrolysis (200 h) at a current density of 10 mA cm⁻². Utilizing Fe-Ni₂P@CeO₂/NF as electrodes for both the HER and OER demonstrates that a potential of merely 1.47 V is sufficient to reach a current density of 10 mA cm⁻², showcasing remarkable durability. Subsequent investigations indicate that the extraordinary efficacy of Fe-Ni₂P@CeO₂/NF can be attributed to its distinctive micromorphology, which enhances the exposure of active sites. Introducing Fe ions facilitates the formation of highly active trivalent nickel ions throughout the catalytic process. Additionally, the presence of both Ce³⁺ and Ce⁴⁺ encourages the catalyst to generate oxygen vacancies, thereby expediting electron transfer. Furthermore, DFT studies have shown that creating the catalyst's surface helps speed up the movement of electrons between the two phases and lowers the energy needed to produce H₂ and O₂.