Study On Preparation And Application Of G-C₃N₄/Bi₂O₂CO₃and G-C₃N₄/β-Bi₂O₃Composite Photocatalysts

Solar energy is a clean, rich and renewable energy. Photocatalysis is one ofeffective methods for utilization of solar energy, including environmental remediation,direct solar conversion of CO2and water vapor into hydrocarbon fuels, andphotocatalytic hydrogen production et al. Recently, the efficient use of solar energy hasdepended on the development of semiconductors that are high in visible-light-drivenperformance. Due to the low valance band and visible light response of Bi-basedphotocatalyst, it is suitable for visible-light photooxidation catalysis. Moreover,graphitic carbon nitride (g-C3N4) is a low-cost substance that shows high thermal andchemical stability as well as amenability towards chemical modification. Herein highlyefficient visible-light-driven photocatalysts for photodegradation of organic pollutantshave been developed. A plausible machanisms was also proposed for photodegradationof organic pollutantsFlower-like Bi2O2CO3and g-C3N4-Bi2O2CO3microspheres with highadsorption ability were fabricated via a facile method. The as-synthesizedsamples were characterized by XRD, FT-IR, SEM, TEM (HRTEM), UV-vis DRSand nitrogen adsorption-desorption techniques. The dye-induced photosensitizeddegradation processs of Bi2O2CO3under visible light irradiation was proved byirradiation of monochromatic visible light. It was found that the activity ofBi2O2CO3was significantly enhanced by modifying Bi2O2CO3with g-C3N4, andthe amount of g-C3N4for optimal activity is10wt.%. The g-C3N4/Bi2O2CO3composite shows good photocatalytic activity and stability towards thedegradation of cationic (rhodamine-B, methylene blue or crystal violet) or) as wellas anionic (methylene orange) dyes. The high visible-light activity is ascribed tog-C3N4being excellent in terms of dye sensitivity. It is deduced that thematching of the energy levels of dye, Bi2O2CO3and g-C3N4facilitates thetransfer of photogenerated electrons and holes, leading to the superiorphotocatalytic activity as a result. The results of the present study give insightsthat are beneficial for the design of heterostructured materials.g-C3N4/β-Bi2O3composites with high visible-light-driven photocatalyticactivity were prepared through calcination of g-C3N4/Bi2O2CO3and characterized by different techniques. The photocatalytic activity of compositeswere investigated through degradation of methylene orange and2,4-dichlorophenolunder visible-light irradiation. The g-C3N4/β-Bi2O3composite resulted fromg-C3N4/Bi2O2CO3with g-C3N4:Bi2O2CO3mass ratio of3:7shows the highestactivity. Photocurrent experimental results indicate that there is high separationand transfer efficiency of photoinduced electron-hole pairs in g-C3N4/Bi2O2CO3.By means of trapping experiments and PL-TA technique, species such as OH, h+and O2were proved to be active species. It was found that g-C3N4/β-Bi2O3composite shows good photocatalytic activity towards the degradation of organicpollutants with low photosensitization, which will extend their application.