Preparation And Research Of Photocatalytic Removal Of NO By SnO₂ Matrix Composites

In recent years,due to the increasingly serious atmospheric pollution,photocatalysis,a clean and green method of degrading pollutants,has gradually attracted attention,and the preparation and modification of photocatalytic materials have also received extensive attention from researchers.As one of the primary air pollution sources,NO has been studied by many researchers.However,in the degradation experiment of NO,it is easy to produce the by-product NO2,which is more toxic.As one of the common photocatalysts,SnO2 has a wide band gap,which limits its photocatalytic capacity.However,SnO2 itself has excellent oxidation capacity,which can completely oxidize NO to reduce the generation of the by-product NO2.Therefore,this study selected SnO2 as the modified object to study the performance and mechanism of its photocatalytic degradation of NO.In this paper,SnO2 was modified by three different schemes,the construction of amorphous/crystalline accumulation structure SnO2,the construction of TiO2/SnO2 heterostructure and composite GO materials.The photocatalytic degradation of NO as a pollutant was studied by XRD,BET,Raman,SEM,TEM,FTIR,PL,UV-Vis absorption spectrum and EPR.The specific content is as follows:In this paper,SnO2 with amorphous/crystalline accumulation structure was successfully prepared by one-step hydrothermal method,and the proportion of amorphous crystallization was controlled by controlling the hydrothermal reaction time.The results showed that the optimal reaction time was 6h.Compared with the samples with less or more hydrothermal reaction time(3 h,9 h and 12 h),the NO removal rate of SnO2-6h samples within 6 min was the highest,reaching 50.2%.The amorphous crystalline area on the surface of the material is selective to the active sites.The special structure of the amorphous crystalline accumulation can isolate the O2 and NO adsorption sites,generating more active free radicals without affecting the photocatalytic reaction get on.Amorphous crystalline region has a built-in electric field between the two regions due to the difference in the energy band structure.The formation of the built-in electric field helps the separation and transmission of photo-generated carriers,and the improvement of photocatalytic performance is related to the amorphous and crystalline regions.It is related to the fast charge separation efficiency of the built-in electric field formed between.In order to further improve the NO removal performance of pure SnO2,we used TiO2 to compound it.In this experiment,the TiO2/SnO2 composites were successfully prepared by one-step hydrothermal method.Due to the matching position of valence conduction band of TiO2 and SnO2 materials,the interface electrons interact with each other in the light,and the valence electrons of SnO2 materials transfer to TiO2 and compound with the holes generated by TiO2 materials,leaving electrons and holes with higher REDOX potential in the composite materials to participate in the photocatalytic reaction.The experimental results show that when the Sn:Ti ratio is 1:1,the material has the best catalytic activity,which is increased by 50%compared with the pure SnO2 material,and the degradation rate reaches 70%.TiO2 light raw material itself electronic output is less,and SnO2 composite material after the light of its own electronic production decrease,output active species needed to influence the reaction,in view of the above problem,we choose GO to SnO2 materials were modified,due to the excellent electronic transmission performance GO materials,can significantly improve the quantum efficiency of material,and reduce the light carrier recombination rate.In this experiment,simple self-assembly method was used to synthesize the material.The results show that when the GO loading is 3%,the material has the best photocatalytic activity.Compared with pure SnO2 material,the NO removal activity increases by 30%to 80%,and the cyclic stability of the material also improves after loading GO.