Preparation And Photocatalytic Properties Studies Of MO_x/CNTs/rGO Composites

Due to their advantages of low cost,availability,non-toxicity and good stability,metal oxide semiconductors?such as Co₃O₄,TiO₂,ZnO,etc.?exhibit excellent physical and chemical properties in optical devices,biological medicine,new energy materials and so on,especially showing potential applications as photocatalysis.However,there are still a few defects in the preparation and photocatalytic degradation of pure metal oxide semiconductors,like particle agglomeration leading to reduction of active sites,higher recombination efficiency of photogenerated electron-hole pairs,narrower light response range and lower sunlight utilization rate,etc.Therefore,the combination of metal oxides with precious metal ions,non-metal atoms,carbon materials,etc.has become a research hotspot of researchers,and it is expected to effectively overcome the above disadvantages.Graphene and carbon nanotubes?CNTs?have large specific surface areas,unique conductivity and mechanical properties,which can usefully prevent the aggregation of nanoparticles,increase the specific surface areas of the catalyst and improve the separation efficiency of photogenerated electron-hole pairs and catalytic degradation property.Based on the above discussions,Co₃O₄,TiO₂,ZnO were combined with reduced graphene oxide?rGO?and CNTs in a relatively simple and moderate experimental procedure to prepare Co₃O₄/CNTs/rGO,TiO₂/CNTs/rGO,ZnO/CNTs/rGO composites,respectively,which were studied their results to degrade Rhodamine B?RhB?under ultraviolet visible light.The specific research contents are summarized as follows:?1?CoSO₄·7H₂O was used as the Co source,and coral-like Co₃O₄ was combined with CNTs/rGO by hydrothermal method and low-temperature calcination method.A series of ternary Co₃O₄/CNTs/rGO composites with different mass ratios of CNTs to Co₃O₄ were prepared.And Co₃O₄/CNTs,Co₃O₄/rGO and pure Co₃O₄ were also prepared according to the optimal ratio.Too much or too little CNTs will reduce the photodegradation effect of RhB for Co₃O₄/CNTs/rGO.The ternary photocatalyst prepared under optimal conditions performed better degradation ability than the corresponding binary composite and single Co₃O₄.?2?Using tetrabutyl titanate as Ti source,ternary TiO₂/CNTs/rGO composites were prepared by solvothermal method.The effect of the amount of CNTs on the photocatalytic degradation performance was explored in the experiments.The structure,morphology,specific surface area,pore size distribution and optical properties of the samples were analyzed by XRD,Raman,FESEM,TEM,fully automatic physical adsorption instrument and solid ultraviolet visible diffuse reflection spectrum.When the mass ratio of CNTs to TiO₂ was 3%,the ternary composite sample had the best photocatalytic effect.After modification by CNTs and rGO,the specific surface area,light absorption intensity and degradation ability of TiO₂ were improved.?3?Ternary ZnO/CNTs/rGO composites were prepared by constant temperature stirring method with Zn?CH₃COO?₂·2H₂O as Zn source.The effects of GO amount,CNTs amount and ZnO content on the photocatalytic degradation performance of RhB were explored.Photodegradation experiments demonstrated that ternary composites prepared at the most suitable ratio showed the most excellent performance.Under ultraviolet-visible light,the photocatalytic efficiency of ZnO/CNTs/rGO was better than that of binary ZnO/rGO and ZnO/CNTs materials and pure ZnO.The excellent photocatalytic activity was mainly attributed to the synergistic effect of the three components,namely ZnO,CNTs,rGO.