Modification And Photocatalytic Properties Of Bi₁₂O₁₇C_l2 Photocatalyst

In recent years,the pollution of environment has been increasingly serious with the development of the society.Semiconductor photocatalysis as an advanced catalysis or oxidation technology was attracted extensive attention of national and international experts.The catalyst is the core of photocatalytic technology.The most common semiconductor catalyst is titanium dioxide?TiO₂?,which has good physical and chemical properties and high photocatalytic activity.However,TiO₂ usually suffers from the low quantum efficiency and incapability of visible-light response.At present,strong response of the visible area and high photocatalytic activity of semiconductor photocatalyst are studied and developed,which have been the hot spots of research.Bismuth oxychloride material is a new kind of perovskite photocatalyst which has gained a lot of attention recently.Parts of the bismuth-based photocatalysts have unique visible-light absorption capacity.Through adjusting the proportion of bismuth oxychloride,it has been successfully prepared into a highly efficient photocatalyst.However,there is relatively little research on another Bi₁₂O₁₇Cl₂,a bismuth oxychloride-rich material with appropriate physical and chemical properties.In this study,various oxygen-rich Bi₁₂O₁₇Cl₂ sample were constructed through noble metal deposition and adding non-metallic carbon nitride to Bi₁₂O₁₇Cl₂,which can get photocatalytic materials with high efficient degradation and selective oxidation of organic under visible light irradiation.The thesis mainly contains two parts:?1?Bi₁₂O₁₇Cl₂ was synthesized through solvent hydrothermal method from bismuth nitrate pentahydrate.Silver nitrate was used as the source of silver which was loaded on the Bi₁₂O₁₇Cl₂by photoreduction method in order to enhance the photocatalytic activity.The produced samples were fully characterized by X-ray diffraction?XRD?,scanning electron microscopy?SEM?,X-ray photo-electron spectroscopy?XPS?,UV-vis diffuse reflectance spectroscopy?UV-vis DRS?,fluorescence spectroscopy?PL?and so on.The photocatalytic activity of Bi₁₂O₁₇Cl₂ can be controlled by adding precious silver?Ag?.Methyl orange?MO?,rhodamine B?RhB?,methylene blue?MB?and tetracycline hydrochloride were selected as a probe molecule of pollutants to measure the photocatalytic degradation performance of Bi₁₂O₁₇Cl₂ under visible light irradiation.The results showed that Bi₁₂O₁₇Cl₂ photocatalytic material with mass ratio of 3%Ag has the best degradations efficiency for MO and tetracycline hydrochloride,better than other catalysts and N-TiO_2?In addition,Bi₁₂O₁₇Cl₂ photocatalytic material with mass ratio of 5%Ag has the best degradations efficiency for MB,better than other catalysts and N-TiO₂.Moreover,bure Bi₁₂O₁₇Cl₂ photocatalytic material without Ag has the best degradations efficiency for RhB,better than other catalysts and N-TiO₂.The degradation mechanism of the dye may be different,and the appropriate band structure is different.What's more,benzyl alcohol was elected as a probe molecule of substrate to measure the photocatalytic selective oxidation performance of Bi₁₂O₁₇Cl₂ under visible light irradiation.The data shows that the series of sample selectivity are as high as 99%.Bi₁₂O₁₇Cl₂photocatalytic material with mass ratio of 3%Ag has the best selective oxidation efficiency for benzyl alcohol,and it is 1.5 times of the pure Bi₁₂O₁₇Cl₂ photocatalytic material.The reasons for the enhanced photocatalytic degradation performance aresmall practical size and the appropriate band structure.Otherwise,we were also carried out to study the photocatalytic activity of the modified oxygen-rich Bi₁₂O₁₇Cl₂ throughadding non-metallic carbon nitride.?2?Bismuth chloride was used as the source of bismuth,and the lamellar carbonitride?CNs?was synthesized of by pyrolysis of melamine.The produced samples were fully characterized by XRD,SEM,UV-vis DRS,PL and so on.Methylene blue?MB?was selected as a probe molecule of pollutants to measure the photocatalytic degradation performance of CNs/Bi₁₂O₁₇Cl₂ under visible light irradiation.The results showed that Bi₁₂O₁₇Cl₂photocatalytic material with mass ratio of 50%CNs has the best degradations efficiency for MB,and were nearly 13.7,6.9 and 5.1 time of that N-TiO₂,pure CNs and pure Bi₁₂O₁₇Cl_2.The reasons for the enhanced photocatalytic degradation performance is the different structure.