Synthesis of the SO42−–Fe3O4/FeS coating catalyst on a TC4 titanium alloy for the enhanced Fenton-like degradation of phenol

Abstract

Immobilized coatings prepared by plasma electrolytic oxidation (PEO) as Fenton-like catalysts exhibit remarkable reusability and considerable prospect; however, the unsatisfactory performance and stability impede their further development. Herein, highly efficient SO₄²⁻–Fe₃O₄/FeS-immobilized ceramic coating on a TC4 alloy as the Fenton-like catalyst was prepared for phenol degradation via the PEO technique. Phase composition and morphologies were investigated by XRD, EDS, XPS and SEM analyses. The coating is composed of SO₄²⁻–Fe₃O₄ and FeS with an abundant pore structure, resulting in a high specific surface area that could provide more reactive sites. The as-prepared coating manifests decent stability and an extraordinary phenol removal efficiency of 100% within 3 min under circumneutral pH. The enhanced Fenton-like performance of the SO₄²⁻–Fe₃O₄/FeS coating is attributed to the introduction of SO₄²⁻ to form strong acid sites and rapid transformation from Fe^III to Fe^II promoted by the S²⁻ group, which endow the catalyst with excellent activity under neutral conditions and outstanding reusability. The advantages of the immobilized PEO coating in this study provide a novel design strategy for the synthesis of high activity Fenton-like catalysts in the future.