Study Of Photocatalytic Activities Of Ag/ZnO And CdS/ZnO Composite Nanostructures

The development of global industrialization is increasingly promoted,accompanied by a series of water pollution problems.For the treatment of waste water,photocatalytic technology has been paid more and more attentions owing to its plentiful advantages such as high efficiency,low cost,and no secondary pollution.Zn O is emerging as a promising metal oxide semiconductor catalyst with high catalytic activity,easily controlled morphology,non-toxic property,and good photochemical stability,which has attracted much attention in the field of photocatalysis.However,Zn O still has the disadvantages that separation and recovery are difficult and the carriers' recombination rate is high.According to the previous research,noble metal loading,semiconductors coupling,and electromotive force imposing can effectively reduce the recombination of photogenerated carriers and improve the photocatalytic performance.In this paper,the Zn O nanorod arrays structure was successfully grown on the conductive substrate by chemical solution method.On this basis,Ag and Cd S were combined with Zn O to study the photocatalytic activity and explore the ways to improve the photocatalytic performance.While these structures favor the catalyst separation from treated solution.The details are as follows:1.Using chemical solution method,Zn O nanorod arrays with different sizes were successfully prepared on ITO substrate by adjusting the seed-layer growth temperature,growth solution type and concentration.The experimental results showed which had average diameter of ~50 and relatively dense arrangement possessed higher photocatalytic degradation efficiency.A total of 59.4% Rhodamine B was degraded after 3 h.2.Utilizing the above optimal conditions,ZnO nanorod arrays were synthesized on ITO,Ag foil,and Ti foil.The photocatalytic and photoelectrocatalytic activity of Zn O nanorod arrays grown on Ag and Ti substrates were higher than that of Zn O nanorod arrays grown on ITO.Under the applied bias voltage of 0.8V,photoelectrocatalytic efficiency of the three prepared samples reached more than 1.5 times of photocatalytic efficiency.The external bias potential can effectively reduce the recombination rate of the photo-generated electron-hole pairs and improve the catalytic activity.3.Through light reduction method,different amounts of Ag nanoparticles were loaded on the surface of the Zn O nanorod arrays to synthesize Ag/Zn O structure by adjusting the Ag NO3 concentration.When the concentration of Ag NO3 solution was 0.05 mol/L,the photocatalytic activity of obtained sample was near to 95.6%.The photocatalytic activities of Ag/Zn O structures declined with increasing the amount of the loaded Ag particles in the experiment range.Loading moderate amount Ag nanoparticles on Zn O nanorod arrays can improve the photocatalytic activity.4.The Cd S thin films were coverd on the Zn O nanorod arrays to form Cd S/Zn O heterostructure by chemical solution method.Under the visible-light irradiation(? > 420 nm),the visible-light catalytic efficiency of Cd S/Zn O heterostructure reached 60% and this efficiency was 6 times that of pure Zn O.Coupling Cd S with Zn O can extend the light response range of Zn O,and then enhance the visible-light photocatalytic activity of Zn O.