Highly efficient photo-Fenton degradation of methyl orange facilitated by slow light effect and hierarchical porous structure of Fe2O3-SiO2 photonic crystals

Abstract

In this work, the Fe2O3-SiO2 composite photo-Fenton catalyst was designed and synthesized as a photonic crystal with a hierarchical macro-mesoporous structure, which possesses a slow-light-effect region that overlaps with the absorption spectrum of methyl orange (MO). The prepared material exhibits remarkably high and stable photo-Fenton catalytic performance for the degradation of MO using only a low concentration of H2O2 under visible light irradiation. The catalytic activity of the as-prepared material is better than that of the corresponding macroporous or mesoporous Fe2O3-SiO2 composites as well as commercial Fe2O3 or the homogenous photo-Fenton system of FeCl3 · 6H2O. The efficient use of H2O2 and the high catalytic activity are attributed to (i) the excellent adsorption of MO by the hierarchical macro-mesoporous structure and (ii) enhanced light harvesting from coupling the absorption spectrum of MO with the slow-light-effect region of the photonic crystal. This hierarchical macro-mesoporous Fe2O3-SiO2 photonic crystal is expected to be a promising cost-effective photo-Fenton catalyst for degradation of a variety of dyes by deliberately tuning its slow-light-effect region, and opens up new perspectives for the development of highly efficient photo-Fenton catalysts for environmental remediation technology.