Mechanism of enhanced photocatalytic activity of rGO/CdS@HAP composite microspheres
In order to improve the photocatalytic activity and stability of CdS-based composite materials,hydrothermal method was employed to coat rGO(reduced graphene oxide)onto the surface of CdS@HAP(hydroxyapatite)microspheres.Techniques including XRD(X-ray diffraction),SEM(scanning electron microscope)and UV-vis(UV-vis absorption spectra)were utilized to characterize the crystal structure and physical and chemical properties of as-obtained samples.And the mechanism of enhanced photocatalytic activity of rGO/CdS@HAP was explored with photocatalytic degradation experiments of MB(methylene blue).The results show that rGO/CdS@HAP presents hollow micro spherical structure with a diameter of 4-5 μm,with tulle-like rGO coated on the surface of CdS@HAP.In addition,rGO/CdS@HAP shows significant absorption capacity for visible light,and the removal efficiency of MB under visible light irradiation for 120 min reaches up to 94％.The photocatalytic cycling experiments confirm efficient photocatalytic activity and good stability of rGO/CdS@HAP microspheres.The mechanism analysis verifies that the enhanced photocatalytic activity of rGO/CdS@HAP is achieved because type I heterojunction between CdS and HAP has a narrow band gap,which is conducive to the absorption and utilization of visible light,and rGO on the surface of CdS@HAP boosts the separation of photogenerated carriers by providing a high-speed transport path for photogenerated holes and inhibits the photocorrosion phenomenon of CdS significantly.
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