Preparation Of α（β）-TPMPc/TiO₂and Its Photocatalytic Activity Under Visible Light Irradiation

In recent years, semiconductor photocatalysis has become a promising technology in thearea of water purification. TiO₂is a kind of semiconductor with wide band gap （3.2eV）, onlythe ultraviolet ray of sunlight can be absorbed and the harvest of solar light is low. So how toimprove the quantum yield becomes a very important problem in the research field ofphotocatalysis. In this paper, with the purpose of enhancing visible-light activity, α（β）-TPMPc(M=Co²⁺、Ni²⁺、Cu²⁺、Zn²⁺) was selected as sensitized materials to modify TiO₂.By the method of in-situ, through the annulations of3（4）-phenoxy-1,2-dicyanobenzeneon the surface of TiO₂with M²⁺as template, α（β）-TPPcM is synthesized in the processing ofTiO₂gel synthesis and obtained the catalyst of α（β）-TPPcM/TiO₂. The as-prepared sampleswere characterized by X-ray diffraction （XRD） and UV-Visible spectroscopy （UV-Vis）. Thephotocatalytic activity of the products was evaluated by the photocatalytic decomposition ofrhodamine B（RhB） under visible light（λ＞450nm）.TiO₂samples prepared by in-situ method were anatase structure and nanometric （3.1-3.5nm and6.0-6.5nm, particle size of101and004）. The light absorption of TiO₂waseffectively extended by α（β）-TPPcM into visible light and the efficiency of photocatalytic washighly improved. Among all the TiO₂samples, α-TPPcNi/TiO₂have the best efficiency ofphotocatalytic, its degradation rate of RhB up to61.4%in2.5h.The photocatalytic activity effectively can be improved by the phenoxy substituted, butthe replaced position of phenoxy has little effect; the central metal was an important factoraffecting the photocatalytic activity of α（β）-TPPcM/TiO₂, the best/worst photocatalyticactivity were respectively found in α（β）-TPPcNi/TiO₂/α（β）-TPPcZn/TiO₂.The experiment on photocatalytic stability indicated that α（β）-TPPcM/TiO₂compositephotocatalyst was stable.