Photocatalytic degradation of methylene blue (MB) by UV-light irradiation using SnO₂/CeO₂ modified nanographene platelets (NGP)

The main task of this present work is to enhance the photocatalytic degradation of methylene blue (MB) under UV-light irradiation by using SnO₂/CeO₂ that combined with nanographene platelets (NGP) composite catalysts. A facile approach for the synthesis of SnO₂/CeO₂/NGp composites was demonstrated via co-precipitation method. The nanographene platelets (NGP) concentrations in composites were altered between 5-15 weight percent (wt.%). The structure and thermal stability obtained composites catalyst were thoroughly studied by various techniques including X-ray diffraction (XRD) and thermogravimetric analysis (TGA), respectively. XRD analysis reveals that the composites have the tetragonal structure of SnO₂ nanoparticle, the cubic phase of CeO₂ and the graphitic-like structure from NGP. TGA curves prove the presence of NGP materials in the composites by the decrement in mass at the temperature about 600°C. The synthesized SnO₂/CeO₂/NGP 10 wt.% composite exhibits higher photocatalytic activities than SnO₂/CeO₂ and pure SnO2 nanoparticles for the degradation of MB dye under UV light irradiation. The photocatalytic activities of the synthesized samples show an increasing degradation in the order of SnO₂<SnO₂/CeO₂<SnO₂/CeO₂/NGP 5 wt.%< SnO₂/CeO₂/NGP 15 wt.% <SnO₂/CeO₂/NGP 10 wt.%. The enhanced photocatalytic performance could be ascribed to the high electron accepting nature of graphene and increase the number of active sites owing to high charge carrier mobility and high specific surface area of graphene material. The other parameter such as catalyst dosage, irradiation time and scavenger were also analyzed to find out the optimum degradation condition. The SnO₂/CeO₂/NGP 10 wt.% composite reach optimum photodegradation when irradiation time, catalyst dosage and scavenger are 120 min, 0.3 g/L, and hole, respectively. The tests for reusability tests have also been conducted to ensure the stability of the used catalysts.