<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>NiFe<sub>2</sub>O<sub>4</sub> is an excellent catalyst for photocatalytic water oxidation with Na<sub>2</sub>S<sub>2</sub>O<sub>8</sub> as a sacrificial oxidant and [Ru(bpy)<sub>3</sub>]<sup>2+</sup> as a photosensitizer.</p> </abstract>