Preparation Of Cu₂O Hollow-opened Nanospheres And Its Photocatalytic Property

As a p-type semiconductor(band gap 2.0 eV)with unique optical and magnetic properties,cuprous oxide(Cu₂O)can be excitated in visible light of 400-800 nm。So, it is regared as a promising material with potential applications in solar energy conversion,photocatalysis and micro-/nanoelectronics.As we know,the quantum efficiency of bulk Cu₂O is quite low but it can be much improved if the scale of Cu₂O is transformed from micrometer to nanoscale.The goal of the thesis is to synthesize nanosized Cu20 with uniform morphologies by simple method,and then to use it for photo-catalysis under visible light.Many reports predict that Cu₂O may be employed as a promising catalyst under visible light.At present,there are some debates in the academia about whether Cu₂O can decompose H₂O to form H2 and O₂ under the sunlight.In 1998,Ikeda et al showed that Cu₂O could decompose H₂O.However,in 1999,Jongh et al reported that it is worth suspecting whether Cu₂O can split water because a p-type Cu₂O photocatalyst does not have the ability to overcome high overpotential for water spilliting.Anyway,Jongh pointed out Cu₂O would be a promising material for direct photoelectrochemical water splitting if it could be composited with other materials.We try to use Cu₂O by coupling with another material to reduce the overpotential for splitting water into H₂ and O₂.In this thesis,based on the two aspects mentioned above,nanosized Cu₂O with new morphology and its photocatalytic activity for degradation of organic pollutant and H₂ evolution from water splitting have been investigated.The detail is as follow.1.Hollow Cu₂O nanospheres with open have been successfully prepared at a relative low temperature by liquid phase method.By XRD,SEM analysis the cuprous oxide nanospheres is maily composed of small particle about 6nm.The BET surface area can reach 116.78 m²/g and the average pore diameter is＜10nm,and this is the biggist BET surface area of Cu₂O nanospheres to be reported so far..The Cu₂O with particle size＜10nm certain quantum size effect.Further control experiments were also carried out to investigate the factors that impact the morphology and size of the products.The results indicate that the growth of the nanospheres follows the growth mechanism of nucleation, crystal growth,and the formation the hollow spheres with open.2.The effect of the prepared cuprous oxide with large specific surface area and assembled by small particle on the photodegradation of the dye Brillant Red X-3B under visible light is investigated in detail.It is found that the photocatalytic activity of the special Cu₂O nanospheres with the presence of FeSO₄ and EDTA is much higher than that for the similar system with only Cu₂O and TiO₂ respectively.The degradation efficiency under visible light can reach 98.26%.3.We use platinum as the metal promoter production for H2 evolution becease Pt is generally regarded as the best one due to its low overpotential.Pt/Cu₂O composite was synthesized by photodeposition method.The samples were characterized by SEM,XRD and EDS.Compeared with the sample of hollow Cu20 nanospheres with open,the composite has exhibited enhanced efficienty for Ha evolution.through water splitting under visible light.