Electrolyte-Assisted Polarization in BiFeO₃/Nickel Foam for The Enhancement of Electrocatalytic Water Splitting

Efficient and long-lasting electrocatalysts with superior performance are essential for the efficient and sustainable production of green hydrogen, ensuring high yield and minimal energy consumption. Electrocatalysts based on transition metal oxides have a significant advantage due to their abundant natural resources, adjustable physical properties, and their compatibility with various solutions. Among the various oxide catalyst materials, ferroelectrics have received attention for their semiconducting properties and switchable spontaneous polarization, particularly as promising photoelectrodes in solar water splitting. However, their potential as electrocatalysts has been largely overlooked until now. Here we present an effective electrocatalytic electrode composed of a BiFeO₃/nickel foam heterostructure. This heterostructure exhibits a lower overpotential and higher current density compared to a bare nickel foam electrode. Additionally, when in contact with an alkaline solution, the interaction between hydroxyls and the BiFeO₃ surface induces a significant area of upward self-polarization. This phenomenon reduces the adsorption energy of subsequent adsorbates and enhances the efficiency of the oxygen and hydrogen evolution reactions. Our work illustrates a unique approach, utilizing functional semiconducting materials for the development of highly efficient electrocatalytic electrodes.