Ferromagnetic nanocrystallines containing copper as an efficient catalyst for photoinduced water oxidation

Abstract

CuFe₂O₄ nanocrystallines with cubic jacobsite structure have been obtained by heat treatment of the coprecipitation product, which were synthesized by the reaction of Cu²⁺ ions and Fe³⁺ ions under alkaline conditions. Reported here is the first copper-based catalyst for photocatalytic water oxidation using [Ru(bpy)₃]Cl₂ as the photosensitizer and Na₂S₂O₈ as the sacrificial electron acceptor, respectively. An apparent TOF value of 1.2 μmol s⁻¹ m⁻² and an oxygen yield of 72.8% were obtained with CuFe₂O₄. The apparent TOF value with CuFe₂O₄ (1.2 μmol s⁻¹ m⁻²) is the highest value among all heterogeneous photocatalytic water oxidation systems. CuFe₂O₄ can be easily separated from reaction solution by magnetic separation while maintaining excellent water oxidation activity in the fourth and fifth runs. The surface conditions of CuFe₂O₄ are slightly absent after examination by X-ray photoelectron spectroscopy (XPS) before and after the photocatalytic reaction.