【摘 要】
：
Graphene oxide (GO),a new and promising material,has been widely used as a co-catalyst in photocat-alytic reactions;however,its capacity as a sole photocatalyst has rarely been investigated.In this study,ultraviolet (UV) light irradiation was used as a mo
【机 构】
：
Department of Environment and Health,State Key Joint Laboratory of Environmental Simulation and Poll
论文部分内容阅读
Graphene oxide (GO),a new and promising material,has been widely used as a co-catalyst in photocat-alytic reactions;however,its capacity as a sole photocatalyst has rarely been investigated.In this study,ultraviolet (UV) light irradiation was used as a modification method to obtain reduced GO (rGO) samples.The samples were used as photocatalysts to examine their visible light photocatalytic activity toward hex-avalent chromium (Cr(Ⅵ)) removal.Atomic force microscopy (AFM),X-ray diffraction (XRD),UV-vis spec-trophotometry,Raman spectroscopy,X-ray photoelectron spectroscopy (XPS),and electron spin resonance(ESR) spectroscopy were applied to interpret the surface and structure changes with UV irradiation.The oxygen-containing functional groups (OFGs) on the GO surface were reduced to defective carbons and π-conjugated C=C (sp2 domains) under UV light;this led to a decrease in the interlayer distance be-tween GO sheets,GO fragmentation,and increased disorder on the GO surface.The restoration of sp2 domains led to a narrower band gap of GO,which favored the GO excitation by visible light to generate electron-hole pairs.The rGO pre-irradiated with UV for 1h (rGO-1),possessing the highest defect density and electron generation efficiency,exhibited the best Cr(Ⅵ) reduction efficiency,which was about three times that of the GO sample;moreover,it outperformed most of the reported GO-based nanomaterials.In addition,low pH and the addition of citric acid as a hole scavenger could further improve the photo-catalytic activity.This study proves that GO or rGO can be used as a sole photocatalyst under visible light to remove environmental pollutants such as heavy-metal ions,and it paves the way for the development of this kind of material and its UV-irradiation modification for further applications.
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