Preparation Of Metalloporphyrin Sensitized Photocatalyst And Its Visible-light Photocatalytic Activity

Environment and energy,are considered as the key issues which restrict and threat the development and safety of human beings.Fortunately,photocatalytic oxidation is proved to be a promising technology to solve the above issues.TiO₂,commonly known as the photocatalytic material,plays key roles in the photocatalytic degradation of pollutants,photocatalytic splitting water,dye sensitized solar cell,and other areas.In this dissertation,we focused on the synthesis of novel metalloporphyrins and organic modification of TiO₂ surface by using the organic small molecules with large ? electronic conjugation systems and by multifunctional groups as bridging bond unit to modify the surface of TiO₂ microspheres.The organic small molecule and bridging bond unit can strengthen the mutual interaction between metalloporphyrin and TiO₂ surface and can accelerate the transport of photo generated electrons to obtain the photocatalytic materials with visible-light photoresponse and excellent performance.The main research conclusions are summarized as following:?1?Porphyrin and metalloporphyrin derivatives are widely utilized in photocatalysis area,due to their particular features of prominent photoelectron properties,easily tunable structure and diversity of central coordinative atoms.In chapter 2,three metalloporphyrin derivatives,tetracarboxyphenyl-porphyrin iron?FeTCPP?,5-?4-aminophenyl?-10,15,20-triphenyporphyrin cupper?CuAPTPP?and tetracarboxyphenyl-porphyrin cupper?CuTCPP?were successfully synthesized.They were characterized by FT-IR,UV-vis and Elemental analysis.?2?The compatibility and photo-response of photocatalytic materials can be significantly improved by modification of its surface.Therefore,the molecules with specific groups can functionalize the TiO₂ surface and broaden its application.In chapter 3,using toluene disocyanate?TDI?as bridging molecule,a bridge bonding conjugated microspheres?FeTCPP-TDI-TiO₂?were successfully synthesized by grafting tetra-?carboxyphenyl?porphyrin iron?FeTCPP?on the surface of TiO₂ microspheres via the reactions between the hydroxyl groups?-OH?of TiO₂ surface and the carboxyl groups?-COOH?of FeTCPP with-NCO?isocyanate groups?of TDI.The FT-IR spectrum revealed that the-OH on TiO₂ surface and the-COOH of FeTCPP reacted with the-NCO of TDI,respectively,to form a surface conjugated microspheres FeTCPP-TDI-TiO₂.The UV-vis DRS analysis demonstrated that the formation of FeTCPP-TDI-TiO₂ remarkably extended its photo-response from UV area to visible light region.The photocatalytic activity of FeTCPP-TDI-TiO₂ was evaluated by using the photocatalytic degradation of norfloxacin?NFC?,tetracycline?TC?and sulfapyridine?SPY?antibiotics in aqueous solution under Xe lamp?150 W?irradiation.And the possible degradation mechanisms of NFC,TC,SPY and the intermidates were also proposed with HPLC spectra.The stability of FeTCPP-TDI-TiO₂ was estimated by recycle utilization experiments.?3?In chapter 4,in order to effectively inhibit falling off of the sensitive molecules from the surface of photocatalysts,the metalloporphyrin tetra-carboxyphenylporphyrin iron?III??FeTCPP?was synthesized and characterized.The conjugated photocatalysts,FeTCPP-SSA/SA-TiO₂ were synthesized by surface chemical bonding with using FeTCPP as sensitizer,2-hydroxy-5-sulfosalicylic acid?SSA?or salicylic acid?SA?as bridging bond molecule,and Degussa P25 as substrate material.The analyses of FT-IR and XPS spectra revealed that the specific organic complexes of FeTCPP molecules bonded on the SSA-TiO₂ surface through stable dibridging bonds,which remarkably strengthened the interaction between FeTCPP and TiO₂.And the dibridging bonds structure significantly accelerated the electrons transport channel.The morphologies and structures of the as-synthesized catalysts were characterized by UV-visible,XRD,SEM,UV-vis DRS and BET.Methylene blue?MB?was used to evaluate the photocatalytic performance of photocatalysts as a photocatalytic degradation pollutant.The degradation mechanism of MB was also illuminated with UV-vis spectra.?4?In chapter 5,dye molecule CuAPTPP-N-paa with large conjugated ? electrons system was successfully synthesized via the diazotize and coupling reactions.And then,it was further utilized to sensitize the TiO₂ particles.The CuAPTPP-N-paa molecules possess sufficient substituted groups.Two benzene rings will provide ? electrons which conjugated with metalloporphyrin to form an electrons transport channel and accelerate the electrons migration.Furthermore,CuAPTPP-N-paa-Ti02 photocatalyst was obtained by incorporating the large molecule dye CuAPTPP-N-paa as a sensitizer onto the TiO₂ surface.The photocatalysts were characterized by XRD,FT-IR,UV-vis DRS and SEM techniques.In addition,the photocatalytic performance of CuAPTPP-N-paa-Ti02 was evaluated by degradations of two kinds of chosen dye pollutants and two other antibiotics as targets.Under the irradiation of Xe lamp,CuAPTPP-N-paa-TiO₂ exhibited high degradation rates on the degradations of MB,Rhodamine B?RhB?,Chloramphenicol?CAP?and Ofloxacin?OFC?.?5?The heterojunction of semiconductor photocatalytic composites is the key facter that affects the photocatalytic performance.For its appropriate band gap and the similar band edge with that of TiO₂,ZnO was frequently utilized in the preparation of photocatalysts or coupling with TiO₂ to synthesize composited material.In chapter 6,ZnO-CuTCPP-TiO₂ photocatalyst was obtained by incorporating the sensitizer CuTCPP between ZnO and Ti02.Its structure and morphology were characterized by XRD,SEM and FT-IR.Its photo-response activity was analyzed by UV-vis DRS and EIS spectra.The photocatalytic performances of ZnO-CuTCPP-TiO₂,ZnO/TiO₂ and same series of catalysts were evaluated by the degradation of MB and RhB as target model.The results indicated that,due to the heterojunction sensitized structure and the regularly uniform morphology,ZnO-CuTCPP-TiO₂ photocatalyst effectively restricted the recombination of e-/h+ and accelerated the electrons transport,exhibited excellent photocatalytic performance.