Degradation of Methylene Blue (MB) Using ZnO/CeO_2/Nanographene Platelets (NGP) Photocatalyst: Effect of Various Concentration of NGP

摘要

ZnO/CeO_2 photocatalysts were loaded on to nanographene platelets (NGP) layer sheets to form ZnO/CeO_2/NGP composites. The synthesized process was achieved by using two-step methods: Sol-gel followed by the hydrothermal method, the concentration of NGP was varied by 5, 10, and 15 wt.%. The as-prepared ZnO/CeO_2/NGP samples were characterized by X-ray diffraction (XRD) and Brunner Emett-Teller (BET). The XRD spectra of all samples exhibit a good agreement with hexagonal wurtzite ZnO and face centered cubic phase of CeO_2, additionally a new peak could be indexed for graphitic-like structures from NGP. The BET result shows that the incorporation of NGP could enhance the specific surface area of ZnO/CeO_2 composites. Furthermore, it is found that addition of NGP in ZnO/CeO_2 composites could enhance photocatalytic activities in methylene blue (MB) dye degradation compared to ZnO/CeO_2 composites. Our results show that addition of 10 wt.% NGP to ZnO/CeO_2 composites exhibits the highest photocatalytic activity. The enhancement of photocatalytic activities can be ascribed to the function of NGP as trap state for the electron. The scavenger tests results indicated that the photo-generated hole would play an important role in the degradation of MB.