Effect of Zn,C Introduction Amount and Calcination Temperature on the Photocatalytic Reduction of Cu2+over ZnO/C/CeO2
In this study,the Zn(OH)2/AR14/Ce(OH)4 precursor was prepared by a co-deposition method using Ce(NO3)3·6H2O as the cerium source,Zn(NO3)2·6H2O as the zinc source,and acidic red 14(AR14)as the carbon source.Then,ZnO/C/CeO2 materials were obtained by calcination of the precursor in a tube furnace under N2 atmosphere at different temperatures.The composite was characterized by X-ray diffraction,scanning electron microscope,Fourier transform infra-red spectroscopy,photoluminescence and X-ray photoelectron spectroscopy.The results showed that the ternary composites were prepared successfully,and that the carbon existed in an amorphous form.Due to the thermal decomposition of the pre-cursor at high temperatures,the synthesized products exhibit porous property.Due to the uniform distribution of reactants in the reaction system,the distribution of Zn,Ce and C in the obtained material was uniform.It can be seen that the introduction of Zn and the formation of Ce3+in CeO2 are conducive to the formation of oxygen vacancies,generating intermediate energy levels and thus broadening the light absorption range.Furthermore,oxygen vacancies can easily capture photoelectrons and thus accelerate their separation from holes in the value band,which can improve the photocatalytic efficiency of the resulted materials.The introduction of C into CeO2 can produce a certain amount of carbon bonds,promote the effective separation of photoelectrons and holes,and improve the photocatalytic activity of the product.The effects of the amount of introduced Zn and C and the calcination temperature on the photocatalytic activity of ZnO/C/CeO2 were investigated by the photocatalytic reduction of Cu2+.The results showed that when the amount of Zn(NO3)2·6H2O in the reaction raw material was 0.5 g,the concentration of AR14 was 0.05 mmol/L,and the calcination temperature was 350 ℃ for the precursor,the photocatalytic reduction efficiency of Cu2+over ZnO/C/CeO2 is the highest,reaching 95.34％.The main reasons for the best photocatalytic performance are the highest oxygen vacancy concentration and maximum number of carbon bonds in ZnO/0.05C/2CeO2-350,resulting in the highest separation efficiency of photogenerated electrons and holes.
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