Synthesis of β-FeOOH/Fe₃O₄ hybrid photocatalyst using catechol-quaternized poly(N-vinyl pyrrolidone) as a double-sided molecular tape

Mussel-inspired linking of β-FeOOH (akaganeite) on core Fe₃O₄ nanoparticles (NPs) was successfully attempted to produce a novel hybrid photocatalyst that facilitates both visible-light-driven photocatalysis and easy recovery using an external magnetic force. A catechol-quaternized poly(vinyl pyrrolidone) was adopted as a double-sided molecular tape between β-FeOOH and the Fe₃O₄ NPs, which successfully incorporated robust molecular linking. The β-FeOOH/Fe₃O₄ hybrid photocatalysts showed photodegradation efficiencies greater than 90% within 3 h of using rhodamine B as a model compound for environmental pollutants upon irradiation of visible light using a lamp through the heterogeneous photo-Fenton-like process in the presence of H₂O₂. The β-FeOOH/Fe₃O₄ hybrid photocatalyst is a promising visible-light-driven photocatalyst due to its narrow band gap 1.79 eV, and it can be repeatedly recovered and recycled up to 4 cycles. This concept of double-sided molecular tape can be widely applied for the generation of novel and robust hybrid nanomaterials, affording synergistic performance enhancements.