The Preparation Of Nano Cu₂O Composite Photocatalysts And Its Photocatalytic Performance

With the development of science and technology,photocatalytic technology has become one of the most researching technologies with its direct use of sunlight,thorough mineralization,low reaction requirements,no secondary pollution and simple operation in the treatment of waste water,waste gas and other fields.However,a single photocatalytic material has defects in degradation efficiency and the stability of the photocatalyst is an important issue.So,how to improve the activity of the photocatalyst has become a new topic in the field of photocatalysis.In this paper,the modification of Cu2 O in semiconductor material is carried out,and the photocatalytic performance is improved by changing the morphology of Cu2 O,loading on GO and composittinganother semiconductor.In order to comparing the effect of photocatalyst after ameliorating by the specific method in the photocatalytic experiment,we studied the degradation of the pollutants with differentphotocatalysts under simulated sunlight.In the experiment,the Cu2 O quantum dots are obtained by a simple reduction step.On this basis,we make Cu2 O quantum dots grown on GO directly to fabricatethe photocatalyst of Cu2O-QDs/GO.For the sake of improving the activity of photocatalyst and its stability,we preparedCeO2-QDs/nano-Cu2 Oby one-step hydrothermal method.The photocatalysts were characterized by XRD,XPS,DRS and TEM to judge the the morphology,composition,character and so on of the photocatalyst.By a variety of characterization methods of comprehensive testing,Cu2O-QDs have a diameter of about 10 nm and disperse evenly on the GO.The diameter of CeO2 is about 7nm and the diameter of Cu2 O is about 35 nm in the complex photocatalyst of CeO2-QDs/nano-Cu2 O.Under the simulated sunlight,the degradation of Rhodamine B(RhB)was studied to evaluate the photocatalytic activity of different composited photocatalysts.The results of photocatalytic experiment were shown as following:(1)The best amount of GO in the photocatalyst of Cu2O-QDs which was 3% and 7% proved by the experiment.The optimum preparation temperature is 180? and the most suitable concentration of NaOH is 8mol/L.The performance of photocatalyst becomes best under the optimum condations included 1 g/L of the photocatalyst content,10 mg/L of the initial RhB pollutant concentration,and pH value of 10.(2)Under the above photocatalytic conditions,the degradation of Cu2O-QDs,Cu2O-QDs/GO and CeO2-QDs/nano-Cu2 O were 61.3%,85.6% and 93.8%,respectively.(3)The degradation rate of CeO2-QDs/nano-Cu2 O was 74.1% after five recycling,and of Cu2O-QDs/GO was 75.1% after four recycling.As for the photocatalytic degradation mechanism of modified photocatalyst,we discussed in the end: By continuously changing the size of the photocatalyst particles,Cu2O-QDs were successfully prepared.Then Cu2O-QDs were combined with GO in order to transferr the photo-electrons to reduce the electron-hole recombination;The composite photocatalyst CeO2-QDs/nano-Cu2 O is used to construct p-n heterojunction,which can improve the separation of electron-hole and improve the photocatalytic efficiency by using the inner electric field and the relative position of energy band.