Study On The Structure And Photocatalytic Properties Of CdS And ZnO-based Composite Materials

In present,the environmental pollution caused by various sources of living wastewater and industrial productions of organic pollutants is becoming more and more serious.Photocatalysis technology is focused on owing to its outstanding ability in mineralizing the organic contaminants into carbon oxide and water.The wide band gap semiconductor material,represented by TiO2 and ZnO,shows good photocatalytic performance.However,these wide band gap conductors can be induced only be the UV light,which decrease the efficiency of the photo quantum and thus limited their practical applications.Developing new synthesis method,metal ions doping and forming heterostructure are the hot pots in the new photocatalysts with good visible light response and photocatalytic efficiency.In this thesis,a sulfur vacancies riched CdS based composite photocatalyst with graphitic carbon nitride(g-C3N4)asmatrix has been synthesized successfully fromtetranuclear Cd-S cluster assembled supramolecular networkby calcination.In this photocatalyst(CdS@g-C3N4),CdS nanoparticles with the size about 5 to 8 nm disperse homogenously in g-C3N4 matrix.During calcination,some coordinated nitrogen atoms dope in the lattice of CdS and replace sulfur atoms,which generates a large number of sulfur vacancies.Under visible light irradiation,CdS@g-C3N4 exhibits very excellent H2 production activitywith a great durability and stability.Besides H2 production,CdS@g-C3N4 also shows excellent photocatalytic activity for Volatile Organic Compounds(VOCs)degradation.The ZnO composite materials have been fabricated through solvothermal method by blending the Fe3+and zinc precusors,the doping amount of Fe3+was varied from 0.01 at.%to 50 at.%.The diffrent doping amount of Fe3+resulted the different crystalline structure of ZnO composites,and other phase of ZnFe2O4 was observed.The methylene blue and acetaldehyde were used as the photocatalytic degradation object,and the photocatalytic activity of as-prepared ZnO composites have been evaluated.The results showed that the photocatalytic activity incresased firstly as the Fe3+doping amount increased from 5 at.%to 15 at.%,and then decreased with the increase of Fe3+doping amount.