Preparation Of Cu₂O Composite Particles And Photocatalytic Degradation Performance Of Dyes

With the rapid development of social economy,there are two major problems about energy shortage and environmental pollution in recent years.Human urgently needs a new and efficient treatment technology to decompose pollutants.As a visible light photocatalytic material,Cu2O has the characteristics of simple preparation,non-toxicity and low price.It has potential application value in degrading pollutants,electrochemical sensors,solar cells and lithium ion batteries.However,the photogenerated electrons of Cu2O are easily recombined with holes,which limits their application properties.The photocatalytic efficiency is improved by modifying Cu2O.In this thesis,Cu2O composite particles were synthesized by solvothermal method using triethanolamine as solvent.The microstructure,surface morphology and photoelectric properties of the catalyst were characterized by XRD,XPS,SEM,UV-Vis and other methods.And the photocatalytic properties of the catalyst were studied.The specific research contents are as follows:(1)The effects of feeding sequence,holding time and surfactant PVP addition on the performance of Cu2O were discussed.The results showed that when the triethanolamine solution is used,the absorption boundary of Cu2O was red-shifted,which improved the response of Cu2O to visible light.When the holding time was 70 min,the prepared Cu2O had high purity and uniform morphology.When the amounts of PVP added were 0 g,0.5 g,1.0 g and 1.5 g,respectively,the morphologies were spherical,cubic,octahedral and polyhedron,and the specific surfaces were 19.58 m2/g,18.21 m2/g,26.18 m2/g and 25.85 m2/g.The order of photocatalytic degradation of MO was:octahedron(86.77%)>cube(70.19%)>spherical(32.00%)>polyhedron(27.60%),and the photocatalytic degradation process accorded with the first-order kinetic equation.The photocatalytic properties of different morphologies of Cu2O for MO and RhB dyes were different,among the octahedral morphology of Cu2O had better photocatalytic performance on both dyes.(2)Ag-Cu2O composite particles were prepared by ultrasonic dispersion method using Cu2O as template.The results showed that the doping of AgNO3 made the absorption boundary of Cu2O red-shift and decreased the forbidden band width.Doping AgNO3 can increase the specific surface area of Cu2O and increase the photocurrent response of Cu2O.The photocatalytic experiments showed that when the addition amounts of AgNO3 were 1 mL,2 mL and 3 mL,compared with Cu2O,the degradation rate of MO was increased by 4.55%,17.22%and 10.61%,respectively,and the photocatalytic degradation process of MO accorded with the first-order power.It showed that doping Ag can improve the photocatalytic efficiency of Cu2O.(3)Platelet BiOCl,with a 75.03 m2/g specific surface area,was prepared by hydrothermal method.BiOCl can completely degrade 10 mg/L RhB in 20 min,and the degradation rate of 30 mg/L MO is 75.58%in 120 min.Reuse experiments showed that after 5 cycles,RhB could still be completely degraded within 40 min.In the process of photocatalytic degradation of RhB,·OH was the main active species.(4)The BiOCl/Cu2O composite particles were prepared by one-step solvothermal method.The effect of BiOCl addition on the properties of Cu2O was investigated.The results showed that the composite BiOCl made blue-shift at the absorption boundary of Cu2O,and increased the forbidden band width from 1.98 eV to 2.03 eV.The morphology of Cu2O was changed by adding BiOCl,and the photocurrent response of Cu2O was improved.When the addition amounts of BiOCl were 5%,10%and 15%,the degradation rates of RhB by BiOCl/Cu2O were 85.43%,86.95%and 74.74%,respectively.The degradation rate of RhB by Cu2O was 70.00%,which indicated that the composite BiOCl can improve the photocatalytic efficiency of Cu2O and the degradation process conformed to the first-order kinetic equation.During the photocatalytic degradation of RhB by BiOCl/Cu2O,·O2-,h+and·OH can degrade RhB,but the main active species were·OH.Reuse experiments showed that compared with Cu2O,the cycle stability of BiOCl/Cu2O was improved.(5)Using the response surface method to investigate the effects of initial concentration,H2O2 addition and catalyst dosage and interaction factors on the degradation rate of RhB.The model has R2=0.9494,indicating that it had a good fit.The verification experiment showed that the relative error between the predicted value and the true value of the model was 0.14%.