Synthesis Of CeO₂/Co₃O₄/g-C₃N₄ Spherical Shell Structure And Its Photocatalytic Properties

Environmental issues have become more serious as the world’s technological level has continued to increase.Because of its high performance,low energy consumption,environmental friendliness,and other benefits,photocatalytic technology has been extensively studied,especially in the field of organic degradation.However,several flaws remain in today’s common photocatalysts.Take TiO₂ for example,which is the most common used and has outstanding efficiency.Due to bandwidth constraints（3.20e V）,TiO₂ can only use ultraviolet light and cannot absorb visible light,i.e.,only 5%sunlight could be used.Besides that,the exceedingly high photo-generated electron-hole pair recombination probability significantly restricts photocatalyst use.A large number of studies show that choosing suitable materials,modeling appropriate morphology,and semiconductor compounding can greatly increase the photocatalyst’s catalytic activity.In this paper,CeO₂/Co₃O₄/g-C₃N₄ is chosen as the research object.Our works include following contents.First,the CeO₂/Co₃O₄（with different ratio）composite spherical shell photocatalyst is fabricated through integrating hydrothermal and thermal decomposition methods with the self-supporting process;g-C₃N₄ is prepared easily by calcining urea;through mechanical mixing methods,CeO₂/Co₃O₄/g-C₃N₄ composite spherical shell photocatalyst is fabricated by using already prepared CeO₂/Co₃O₄ and g-C₃N₄ samples.Then,the morphology and optical property of the produced samples are characterized using XRD,SEM,TEM,ultraviolet-visible diffuse reflectance spectroscopy.Next,the photocatalytic activity of the as-prepared CeO₂,Co₃O₄,CeO₂/Co₃O₄ and CeO₂/Co₃O₄/g-C₃N₄ spherical shell structures is evaluated under visible light with MB as the target degradation product.After H₂O₂ developed a photo-Fenton framework,the photocatalytic activity of CeO₂/Co₃O₄/g-C₃N₄ composite spherical shell structures also been studied.（1）The produced single-phase CeO₂,Co₃O₄,and CeO₂/Co₃O₄ composite samples all have a hollow spherical shell structure,which are pure single-phase,with good crystallinity,the particle sizes are about 1μm-3μm.The surface of the CeO₂ spherical shell structure is smooth and the shell thickness is thin;the surface of the Co₃O₄spherical shell structure is more wrinkled and the sphere-shell is thick.The photocatalytic activity of the CeO₂/Co₃O₄ composite sample is higher than CeO₂,Co₃O₄ samples.When the molar ratio of CeO₂ to Co₃O₄ is 1:1,it has the highest photocatalytic activity,and the removal rate of MB exceeds 28%after 2 hours of photocatalytic reaction.（2）Adding g-C₃N₄ to the CeO₂/Co₃O₄ composite sample with a molar ratio of 1:1,the photocatalytic activity is further improved.When the amount of g-C₃N₄ added is10%of CeO₂/Co₃O₄,the removal rate of MB reaches 48%after the photocatalytic degradation reaction,and the reaction rate is 2.6 times than that before.（3）After adding a small amount（50μL）of H₂O₂ to form a photo-Fenton system,the photocatalytic activity of the CeO₂/Co₃O₄/g-C₃N₄ composite hollow spherical shell structure sample can be further improved during the removal of organic dye MB.In the final 2h photocatalytic degradation reaction,the MB removal rate is about 71%,and the reaction rate constant is about 8.33×10^-3.