Synthesis Of Bimetal Oxide Derived From Bi-based MOF And Its Photocatalytic Performance

Photocatalytic technology has the advantages of utilizing abundant solar energy,recyclability,complete mineralization of pollutants,no secondary pollution,etc.which is considered to be a environmentally friendly water treatment technology with great potential for application.MOFs can make up for the shortcomings of ordinary semiconductor catalysts due to their structural diversity,high specific surface area,high porosity,and semiconductor-like properties.Therefore,the MOFs materials have attracted the attention of more and more researchers.However,pure MOFs materials are prone to structural collapse,metal ion leaching and high complexation rate of photogenerated electron-hole pairs during photocatalytic process,which reduce the photocatalytic activity,and limit the practical applications of MOFs as photocatalysts.Aiming at the bottleneck problem of novel design of MOFs photocatalyst structure and high electron-hole pair recombination rate,we use CAU-17 and Ce-BTC as the research precursors in this paper,to construct MOFs using post-solution modification doping and crystal engineering methods.Finally,the heterojunctions are obtained by chemical vapor deposition method to improve the photocatalytic efficiency of the system.We investigated the mechanism of the MOFs construction method on the electron-hole separation efficiency and synergistic photocatalysis,and aimed to find an effective,stable and controllable MOF-based photocatalyst construction method,in order to provide a theoretical basis and guiding ideas for the subsequent research on enhancing the photocatalytic efficiency of removing micro-pollutants in water.The main research and results of this paper are as following:（1）CAU-17 was synthesized by hydrothermal method,and then Bi OCl/Zn O composites were prepared by solution doping and heat thermal decomposition.The experimental results showed that Bi OCl and Zn O formed a heterojunction structure,which increased the absorption range of light,effectively improved the separation efficiency of electrons and holes,and improved the photocatalytic performance.The degradation rate of MB（10 mg/L）on BOZC3was 97%under 120 min of light irradiation.After 60 min of light irradiation under the condition of p H=3,it almost completely degrades Rh B（10 mg/L）.The test and analysis results show that h⁺、·O₂^-and·OH are the main active species in the BOZC3 photocatalytic reaction process.It shows that proper post-modification ion doping can effectively improve the utilization rate of sunlight,inhibit the electron-hole recombination process,and effectively enhance the photocatalytic effect.（2）Atomic-level substitution of Ce-BTC was achieved by cleverly utilizing crystal engineering methods to interpolate Bi ions into Ce-BTC,and bimetallic oxide Bi₂O₃/Ce O₂heterojunction materials were prepared by chemical vapor deposition.When Bi:Ce=1:5（BC-3）,the heterojunction material has the best photocatalytic effect.After 30 minutes of visible light irradiation,the TC（10 mg/L）was almost completely degraded.The results showed that Bi₂O₃ and Ce O₂ have formed a heterojunction structure,which not only improved the specific surface area and the adsorption performance,but also improved the photocatalytic performance of the composites to improve the migration efficiency of photogenerated carriers.The analysis results show that h⁺is the main active species in the photocatalytic reaction process.The crystal engineering methods fully reflect the effective relationship between structure and properties of the photocatalytic materials,forming an adsorption/catalysis synergistic effect,thus significantly enhancing the photocatalytic effect.