Preparation And Performance Research Of TCPP Organic Semiconductor Photocatalyst

Semiconductor photocatalysis technology has shown great potential for solving current global environmental problems.Compared with traditional inorganic semiconductors,organic semiconductors have attracted widespread attention in recent years because of their unparalleled advantages.In this article,two types of photocatalysts containing 5,10,15,20-tetra（4-carboxyphenyl）porphyrin（TCPP）,graphene quantum dots modified self-assembled TCPP and partially modified porphyrin coordination MOFs TCPP-UiO-66-NH₂ were explored;which successfully overcomes the shortcomings of easy recombination of photo-generated carriers in monomer TCPP and the narrow visible light response range of NH₂-UiO-66.And both photocatalyst exhibit a high efficiency and stability photoactivity in the of solving environmental problems.At the same time,varieties of characterization methods were taken out to conduct a comprehensive and in-depth study on the photocatalytic properties,composition morphology,energy band structure and photocatalytic activity of the photocatalytic materials.The pre-prepared self-assembled TCPP nanorods and graphene quantum dots were combined by ultrasonic in an acid solution with p H=1.The results showed that graphene quantum dots are uniformly distributed on the surface of self-assembled TCPP nanorods,and the modification of graphene quantum dots will not cause changes in the structure and band gap of self-assembled TCPP.Under the irradiation of full light in the xenon lamp,the degradation efficiency of 20 ppm organic pollutants reaches 85%,which is 1.6 times that of self-assembled TCPP,and it showed excellent photocatalytic performance stability.The active species characterization found that the active species of self-assembled TCPP are superoxide radical（·O₂^-）,hydroxyl radical（·OH）and singlet oxygen（¹O₂）,but for the self-assembled TCPP modified by graphene quantum dots produces,the amount of·O₂^-and·OH rose sharply,and the characterization did not find the presence of ¹O₂.Therefore,this article analyzes the carrier separation form of the self-assembled TCPP photocatalyst after the modified by graphene quantum dots,and proposes a possible photocatalytic degradation mechanism in the article.TCPP-UiO-66-NH₂,partially modified coordinated with TCPP in NH₂-UiO-66,which resulted a multi-element MOFs that integrates adsorption and photosensitivity in the application for the photoreduction of hexavalent chromium ion（Cr（Ⅵ））.The influence of TCPP content,p H and light absorption range on the photocatalytic reduction of Cr（Ⅵ）by TCPP-UiO-66-NH₂ was explored.It was found that after TCPP modification,the photocatalytic absorption range of TCPP-UiO-66-NH₂ broadened to the visible region,and the photocatalytic performance reached the maximum after 15mg TCPP modification.Under the condition of p H=1,it has the performance of nearly100%photocatalytic reduction of Cr（Ⅵ）in 80 minutes,and the first-order degradation kinetic constant is 10 times higher than that of NH₂-UiO-66;compared with the photocatalytic performance of TCPP-UiO-66-NH₂ under full light irradiation,the photoactivity of TCPP-UiO-66-NH₂ exhibited no change when it was under visible light irradiation.Finally,this article analyzes the relationship between the structure and performance of the TCPP-UiO-66-NH₂ modified with TCPP,and proposes the possible principle of photocatalytic reduction of Cr（Ⅵ）...