Pt coupled ZnFe2O4 nanocrystals as a breakthrough photocatalyst for Fenton-like processes – photodegradation treatments from hours to seconds

Abstract

A stable magnetically recyclable extraordinary photocatalyst for Fenton-like processes, Pt coupled ZnFe₂O₄ nanocrystals (Pt/ZnFe₂O₄), was developed, which makes possible the shortening of photodegradation treatment times from hours to seconds. Pt/ZnFe₂O₄ nanocrystals (NCs) were prepared by simply mixing ZnFe₂O₄ NCs with Pt NCs, produced by a carrier solvent assisted interfacial reaction process and a polyol process, respectively. The extraordinary organic pollutant degradation efficiency of the Pt/ZnFe₂O₄ NCs was demonstrated with rhodamine B (RhB) degradation in a Fenton-like process under illumination of simulated sunlight at 100 mW cm⁻². The apparent reaction rate constant can reach as high as 9.31 min⁻¹, almost three orders of magnitude higher than 0.01 min⁻¹ typically achieved by photocatalysts reported in the literature. The excellent magnetic recyclability and cycling stability of the Pt/ZnFe₂O₄ NCs toward RhB degradation were also demonstrated. A degradation mechanism was proposed to show how the coupling of Pt enhances the charge separation of ZnFe₂O₄ NCs and generation of HO₂˙ and HO˙, all significant factors to boost the RhB degradation efficiency. The Pt/ZnFe₂O₄ NCs prove to be an extremely efficient and promising catalyst for Fenton-like processes for the removal of recalcitrant organic pollutants and greatly increase the competitiveness and practicality of photocatalytic degradation in pollutant control.