Preparation And Photocatalytic Properties Of S,Fe,Cu Doped SnO₂ Heterojunction

Economic development is often accompanied by increasingly serious water pollution problems.A large number of unused high chroma dyes,surfactants and trace metals were detected in the wastewater.The waste water has a great damage to the environment,researchers all over the world are looking for appropriate treatment methods.Photocatalytic technology has been widely studied because of its good stability and low secondary pollution and other advantages.SnO₂ is a traditional metal oxide semiconductor.It has a tunable band structure and has great potential in photocatalysis.However,SnO₂ has a wide band gap（3.6e V） and can only absorb sunlight within 344 nm,and its photogenerated carriers are easy to reorganize.g-C₃N₄ is a kind of narrow band gap semiconductor with layered structure,which has a high visible light response range,is easy to synthesize,and is cheap.It is the most widely studied photocatalyst material at present.But,there are still some disadvantages in photocatalysts,such as low separation rate of photogenerated charge,uneven dispersion of loaded samples and so on.The modified SnO₂ can not only absorb visible light,but also effectively inhibit the recombination of photogenerated charges,improve the photocatalytic performance,and provide new ideas for the future research of new photocatalysts.In this paper,SnO₂ was mainly modified.Different proportions of S doped SnO₂ and Fe doped SnO₂ were prepared by simple and feasible precipitation method.Different mole ratios of Cu doped SnO₂ were prepared by hydrothermal method,and the modified SnO₂ materials were combined with g-C₃N₄ to form heterojunction materials,respectively.Methylene blue（MB）and rhodamine（RhB）were degraded under light,and the photocatalytic properties of the sample were analyzed.The bactericidal properties of the material against Escherichia coli and Staphylococcus aureus were also studied.The main research contents are as follows:1、SnCl₄ was used as the precursor of SnO₂,S-doped SnO₂（TS） was prepared by precipitation ball milling method,g-C₃N₄ was prepared by direct calcination,S-doped SnO₂ and g-C₃N₄ were compounded in water to prepare Type-Ⅱ composite.The photocatalytic properties of the samples were evaluated by degradation of RhB and MB under light,and the optimal content of S-doped SnO₂ was determined.A series of spectra,such as SEM and XRD,were characterized,and the composition of the samples was analyzed in detail.Finally,the Type-Ⅱ photocatalytic mechanism was described according to the semiconductor band gap and free radical capture experiments.2、Fe doped SnO₂（Fe-SnO₂） was prepared by precipitation baking method with SnCl₂ as the precursor of SnO₂.g-C₃N₄ was prepared by the same process.Fe-SnO₂ and g-C₃N₄ were compounded in water.The morphology,composition of the composites were analyzed in detail,through the test and characterization.The best doping ratio was selected by photocatalytic degradation of RhB and MB,which was used for sterilization.Finally,the Z-scheme photocatalytic mechanism was described according to the semiconductor band gap and free radical capture experiments.3、By changing the synthesis method and elements,the precursor of SnCl₂ remains the same.Cu doped SnO₂（Cu-SnO₂）was prepared by hydrothermal baking method.The composite dispersant of Cu-SnO₂ and g-C₃N₄ was replaced,and the Z-scheme heterojunction material of Cu-SnO₂/g-C₃N₄ was synthesized.The morphology and composition of Cu-SnO₂/g-C₃N₄heterojunction material were analyzed.The best doping ratio was selected by photocatalytic degradation of RhB and MB,which was used for sterilization.