Research On BiOCl/Ag₂O/Bi₂O₂CO₃ Ternary Photocatalyst With High Efficiency

Considering the broad application prospects of semiconductor catalyst technology in environmental protection and energy conservation,the preparation and properties of semiconductor photocatalysts have attracted much attention from academia and become the hot direction of new material science research.From the beginning,there is only one photocatalyst that is titanium dioxide excited in the infrared light field,to the present in visible region to stimulate the silver and bismuth type photocatalyst,the research in the field of photocatalysis has become increasingly in-depth.At present,the photocatalyst has a wide application prospect in the field of solar cell,degradation of organic pollutants and photocatalytic hydrogen production.The photocatalytic properties of the materials are often related to the composition,size and morphology of the materials themselves.Most of the monomeric catalysts cannot be put into practical production due to the issues of wide band gap,small specific surface area,easy recombination of photogenerated electrons and electron holes,which lead to low photocatalytic activity of these catalysts.Because of lamellar structure with property of easy stacking,the bismuth oxybromide photocatalysts can provide sufficient polarization space,suitable forbidden band width,high specific surface area and porosity,and thus they have good photocatalytic activity.However,for the bismuth oxybromide catalysts,their photoexcited electron-hole is short-lived and the recombination occurs rapidly,so it is difficult to achieve the practical application.Silver oxide is a narrow bandgap photocatalytic material,but a single silver oxide photocatalyst has low utilization of visible light,and is prone to light corrosion to produce element Ag.The photocatalytic activity of bismuth carbonate is mainly related to the microstructure of bismuth carbonate,including zero-dimensional structure,one-dimensional structure,two-dimensional structure,three-dimensional structure,but an unmodified bismuth oxide with wide band gap,has low utilization of visible light.Therefore,it is of great practical significance to study the preparation of highly efficient photocatalytic materials by simple and environmentally friendly synthesis methods.In this paper,ternary BiOCl/Ag₂O/Bi₂O₂CO₃ composite photocatalysts are prepared by two-step reaction method,which has very high photocatalytic activity and is very important for the practical application of photocatalysts.The main achievements of the paper are as follows:?1?The ternary BiOCl/Ag₂O/Bi₂O₂CO₃ composite photocatalyst was prepared by two-step reaction method using bismuth oxychloride as bismuth source.The results indicate that the ternary photocatalyst is composed of nanometer flaky bismuth oxychloride,nanometer globular silver oxide and nanometer barbed bismuth carbonate by comparing the composition and morphology of bismuth oxychloride,silver oxide and bismuth oxychloride.Finally,the photocatalytic activity of the product was characterized by UV-Vis spectroscopy.Repeating this experiment for several times,then the results show that the synthesized ternary BiOCl/Ag₂O/Bi₂O₂CO₃ sample acts as catalyst with high photocatalytic activity in the visible light which plays a role in catalyzing the degradation of organic pollutants.It has a broad prospect as an excellent photocatalyst in the field of degradation of organic pollutants in the future.?2?By adjusting the molar ratio of sodium hydroxide and sodium carbonate in the reactants,different samples were respectively prepared at ratio of 3: 1,4: 1 and 5: 1.After characterization of XRD and SEM and analyzing the composition and morphology of each sample,the results indicate that all three samples are composed of bismuth oxychloride,bismuth carbonate and silver oxide,but the content of bismuth carbonate is different.And after carrying out photocatalytic degradation of methyl orange,it was found that the photocatalytic activity of the samples increased first and then decreased with the increase of the molar ratio of bismuth carbonate and bismuth oxychloride.The results show that the photocatalytic activity is the best when the molar ratio of sodium hydroxide and sodium carbonate is 4: 1.?3?Eventually,the three groups of samples were prepared by adjusting the molar ratio of bismuth oxychloride and silver nitrate in the reactants to 2: 2,2: 3 and 3: 2,respectively.After XRD and SEM characterization,the composition and morphology of the samples were the same,which was composed of bismuth oxychloride,bismuth carbonate and silver oxide without generation of other impurities,but the molar ratio of Bi:Ag is different.The photocatalytic experiments demonstrate that the photocatalytic activity of the samples increased first and then decreased with the increase of the molar ratio of Bi:Ag.The experimental studies demonstrate that the optimal parameters are obtained when the molar ratio of bismuth oxychloride and silver nitrate is 2: 2 and the photocatalytic effect is the best in this case.