Synthesis And Characterization Of Dye-sensitized TiO₂ Photocatalyst

The dye-sensitized semiconductor photocatalysis technology is to prepare a composite photocatalyst through the loading of dye sensitizer and TiO₂.It uses the advantages of dye sensitizers in the visible light region with excellent light absorption performance and small energy band gap to enhance the photocatalytic activity of TiO₂,and provides a way of thinking and means for efficient use of solar energy,solving energy crisis and environmental pollution.The experiment of dye-sensitized TiO₂photocatalytic degradation of rhodamine B and the experiment of photodegradation of splitting water to hydrogen were studied to study the effect of dye sensitization and dye co-sensitization on the photocatalytic activity of TiO₂.Two zinc phthalocyanine dyes tetra（butyl formate-phenoxy）zinc phthalocyanine（Zn TBPP）and tetra（tert-butyl-phenoxy）zinc phthalocyanine（Zn TTPP）were synthesized by4-nitrophthalonitrile,Butyl p-hydroxybenzoate,4-tert-butylphenol as raw materials.TiO₂nanorods（PN）are prepared by hydrothermal method using TiO₂nanoparticles（P25）as raw materials,Four kinds of composite photocatalysts（Zn TBPP/P25,Zn TTPP/PN,Zn TBPP/P25,Zn TTPP/PN）were prepared by hydrothermal method using zinc phthalocyanine Zn TBPP,Zn TTPP and P25,PN.The structure,morphology,crystal form and performance of zinc phthalocyanine and composite photocatalytic materials have been characterized and analyzed by Fourier infrared spectroscopy（FT-IR）,proton nuclear magnetic resonance spectroscopy（1HNMR）,scanning electron microscope（SEM）,X-ray crystal diffraction（XRD）,Solid diffuse reflectance ultraviolet spectroscopy（UV-Vis-DRS）,fluorescence spectroscopy（PL）,universal density function theoretical calculation（DFT）,N₂adsorption-desorption curve（BET）.The photocata-lytic activity of the catalyst was studied by the photocatalytic degradation of rhodamine B.The results show that Zn TBPP/P25,Zn TTPP/PN,Zn TBPP/P25,Zn TTPP/PN have higher photocatalytic activity than TiO₂,and Zn TBPP/PN has the highest photocatalytic activity.Zn TBPP and Zn TTPP can optimize the energy level structure of TiO₂,reduce electron-hole recombination,expand the light response range of TiO₂,and enhance the light absorption performance of the photocatalyst.The photocatalytic activity of nanorods is stronger than that of nanoparticles because the nanorod-like structure has a larger specific surface area and provides more active sites for photocatalytic reactions.Tetra（methyl formate-phenoxy）phthalocyanine（TMPP）is prepared with 4-nitrophthalo-nitrile and methyl p-hydroxybenzoate as raw materials.Tetra（methyl benzoate）porphyrin（TMBP）is prepared with methyl p-aldehyde benzoate and pyrrole as raw materials.The P25/Pt composite material is prepared by the photoreduction method using P25 and H₂Pt Cl₆as raw materials,and Pt is used as a cocatalyst for photolysis of water to produce hydrogen.Three composite photocatalysts were prepared by hydrothermal method,namely TMPP/P25/Pt,TMBP/P25/Pt,TMPP/TMBP/P25/Pt,using TMPP,TMBP,and P25/Pt as raw materials.The structure and performance of TMPP/P25/Pt,TMBP/P25/Pt,TMPP/TMBP/P25/Pt are characterized and analyzed by UV,UV-Vis-DRS,FT-IR,and SEM.The hydrogen production efficiency of the photocatalyst was studied through the photolysis of water splitting to produce hydrogen.The results show that the hydrogen production efficiency of TMPP/P25/Pt,TMBP/P25/Pt,TMPP/TMBP/P25/Pt is higher than that of P25/Pt,and the hydrogen production efficiency of TMPP/TMBP/P25/Pt is the highest,reaching 14.95μmol/h.Dye sensitization can increase the light absorption performance of TiO₂.It is worth noting that when the two dyes are sensitized together,the spectral absorption range of TMPP/TMBP/P25/Pt reaches 200 nm～800 nm,which improves the light absorption performance of TiO₂.The co-sensitization of the two dyes has excellent performance in increasing the photocatalytic performance of TiO₂,which has great research significance.