Enhanced visible light catalysis activity of CdS-sheathed SrAl2O4:Eu2+,Dy3+ nanocomposites

Abstract

SrAl₂O₄:Eu²⁺,Dy³⁺ long afterglow phosphors with one-dimensional nanostructures were synthesized by a hydrothermal method followed by post-annealing, and subsequently CdS was uniformly coated on their surfaces by a sol–gel approach. The nanocomposite system can significantly enhance the photocatalytic activity for the degradation of methyl orange and hexavalent chromium under ultraviolet and visible light irradiation. After the modification treatment with a 1 : 2 molar ratio of CdS to SrAl₂O₄:Eu²⁺,Dy³⁺ nanophosphors, the degradation rate of methyl orange can increase by 2.5 times and reach a maximum of 96.3% under visible light illumination for 30 min. The enhancement of photocatalytic activity originates from the improvement of light usage efficiency due to the hole migration from SrAl₂O₄:Eu²⁺,Dy³⁺ phosphors to the CdS semiconductor and the reutilization of SrAl₂O₄:Eu²⁺,Dy³⁺ luminescence.