Preparation And Photocatalytic Performance Of Rare Earth Oxide@C Using Acid Dyes As Carbon Source

Because the composition of dye wastewater is complex,the degradation difficulty coefficient is large.At present,photocatalysis technology is one of the most promising technologies for degrading pollutants.The photocatalysts used in the process are mainly semiconductor oxides,such as TiO₂,CeO₂,Fe₃O₄,etc.At the early stage of the development of photocatalytic technology,TiO₂ has been highly favored by researchers because of its excellent catalytic performance,high oxidation ability and low cost.However,due to its narrow absorption range of sunlight,low utilization rate and high recombination rate of photogenerated carriers,its practical application is limited.Therefore,the researchers turned their attention to other semiconductors.CeO₂ is favored by scientific researchers due to its special electronic and optical structure and low price.Due to its rapid oxidation state transition and the highest oxygen ion mobility among lanthanide oxides,Pr has also attracted the attention of photocatlyst researchers.Carbon has high-efficiency electronic conductivity,high absorption of visible light,and easy to form heterojunction photocatalyst as a bridge,so it is a commonly used species in the field of photocatalyst.The dye in wastewater has abundant carbon source,if it is used as carbon source,it will reduce the experimental cost and environmental pollution.On the basis of the above ideas,the Ce-Pr-O@C、Ce-Pr-Fe-O@C and Pr₆O₁₁@C photocatalysts were synthesized with acid dyes as carbon sources.The performance of its photocataluytic degradation of dye molecules and the influencing factors have been studied.The details are as follows:1.Study on the preparation and photocatalytic performance of Ce-Pr-O@C using acid dyes as carbon sourceThe Ce and Pr hydroxides are synthesized by the coprecipation method,and then the hydroxides are used to adsorb dyes,following calcination to form Ce-Pr-O@C composite materials.The photocatalytic performance of the catalysts synthesized with different amounts of Pr and the introduction of different amounts of C have been investigated in depth.The UV-visible absorption spectrum shows that that when the doping amount of Pr is 25%and the 0.075 mmol/L of AR14 is used as the carbon source to introduce the C,the photocatalytic performance of the synthesized product is the best.The main reason is that there are more oxygen vacancies and more carbon bonds in the material,which is beneficial for the separation of photogenerated electrons and holes.2.Study on the preparation and photocatalytic performance of Ce-Pr-Fe-O@C using acid dyes as carbon sourceIn this study,using Ce（NO₃）₃·6H₂O,Pr（NO₃）₃·6H₂O,Fe（NO₃）₃·9H₂O as raw materials,dyes were used as carbon soucres,a series of Ce-Pr-Fe-O@C samples were prepared by coprecipitation method.X-ray diffraction（XRD）,scanning electron microscopy（SEM）,Raman,UV-Vis and X-ray photoelectron spectroscopy（XPS）were used to characterize the materials.The synthesized product is cubic fluorite structure.The photocatalytic results show that the photocatalytic degradation efficiency of Ce-Pr-Fe-O@C1 material for AR14 solution is higher than those of other catalysts.After 4 hours of illumination,0.15 mmol/L AR14 solution can be almost degraded.The main reason is that the material has high utilization ratio of visible light,and more oxygen vacancies and various types of carbon bonds are formed inside,which is beneficial for the separation of photogenerated electrons and holes.3.Study on the preparation and photocatalytic performance of Pr₆O₁₁@C using acid dyes as carbon sourcePr（OH）₃@dye complex was synthesized by coprecipitation,following by calcination in a tube furnace to form a stable Pr₆O₁₁@C material at room temperature.UV-Vis drs analysis shows that Pr₆O₁₁@C-3 absorption of visible light is higher than those of other samples.Raman spectra indicate that the number of Pr³⁺and oxygen vacancies in the sample Pr₆O₁₁@C-3 is greater than that of Pr₆O₁₁,and thus the photocatalytic efficiency of the former is stronger than that of the latter.photocatalytic experiments show that Pr₆O₁₁and Pr₆O₁₁@C-3 photocatalysts can degrade 0.3 mmol/L AR14 solution completely without addition of any other oxidants under 3 hours illumination,Moreover,Pr₆O₁₁@C-3 photocatalytic degradation rate of AR14 is slightly higher than that of Pr₆O₁₁.Because after the introduction of carbon,the absorption of visible light and the separation efficiency of photogenerated electron and hole pair are improved.