Preparation And Photocatalytic Performance Of CNT Loading Ag Modified LaCoO₃ Composite Powers

Photocatalytic degradation technology is recognized as an effective,green and sustainable method in wastewater treatment and environmental remediation.Lanthanum cobaltate has become an attractive new type of photocatalyst due to its unique crystal structure,proper size band gap,and visible light response characteristics.However,pure lanthanum cobaltate has low photocatalytic activity due to insufficient visible light absorption,slow charge transfer,and rapid recombination of light-induced charge carriers.Therefore,a high-performance lanthanum cobaltate is prepared by using noble metal doped lanthanum cobaltate loaded on carbon nanotubes.LaCoO3 composite powders with different Ag modifying amounts were prepared by sol-gel method,using X-ray diffraction,Fourier transform infrared spectrum,X-ray photoelectron to analyze the phase,structure and composition of the material;using scanning electron microscope and transmission electron microscope to observe the morphology of the sample;using UV-visible diffuse reflection spectrum,fluorescence spectrum,photocurrent test and other means to characterize photocatalytic performance of samples.The photocatalytic performance of La CoO3 with different Ag-modified contents was studied by experiments of photocatalytic degradation of Direct green dye.The experimental results show that the modifying of Ag significantly improves the utilization of visible light by the sample.The 1 wt.%Ag modifying has the highest photogenerated electron-hole separation efficiency and the best photocatalytic degradation performance.The sol-gel method was used to prepare LaCoO3 composite powders with different CNT loadings and 1 wt.%AgNPs modifying.Through photocatalytic degradation of Direct green,the photocatalytic performance of composite powders with different CNT loadings was evaluated.The results show that when the content of CNT in the composite is 10%,the composite powder has a Direct green degradation of 99%after 3h light,and the photocatalytic activity is the highest,which is attributed to the synergistic effect between Ag,LaCoO₃ and CNT.Repeatability experiments show that the prepared 1%AgNPs-La CoO3-10%CNT samples have good stability.The inhibitors were used to determine the active substances in the photocatalytic process,and the mechanism of dye degradation reaction was discussed.It can be seen from the results that in the experiment of photocatalytic degradation of Direct green,holes?h⁺?play a major role,superoxide radicals?·O₂^-?play a secondary role,and hydroxyl radicals?·OH?have little effect.