| Recently,the mesoporous TiO2 have been used in various fields owning to their special morphology,outstanding semiconductor property and the splendid photoelectrical properties,which have a far-reaching influence on the development of the materials.Whereas,the large energy gap as well as the recombination of photoinduced electrons and holes restrict their use as photocatalyst seriously.The key to solve this problem is narrowing their energy gap and delaying the recombination of photoproduced electrons and holes.As we all know,porphyrin can absorb the visible light effectively with stable chemical property.For this reason,porphyrin is often used as sensitizer to improve the activity of the TiO2.In our paper,we synthesized four porphyrin compositions with ester group:5-(4-carboethoxy-methyleneoxy)phenyl-10,15,20-tri(4-tertiary butyl)phenyl porphyrin,marked H2Pp(l);5,15-di(4-carboethoxy-methyleneoxy)phenyl-10,20-di(4-tertiary butyl)phenyl porphyrin,marked H2Pp(2);5,10,15-tri(4-carboethoxy-methyleneoxy)phenyl-20-(4-tertiary butyl)phenyl porphyrin,marked H2Pp(3);5,10,15,20-tetrakis(4-carboethoxy-methyleneoxy)phenyl porphyrin,marked H2Pp(4);and their corresponding metalloporphyrin,marked:CuPp(la),CuPp(2a),CoPp(2a),ZnPp(2a),CuPp(3a),CuPp(4a).After hydrolyzation of the metalloporphyrin,we obtained the metalloporphyrin with carboxyl group,marked CuPp(1b),CuPp(2b),CoPp(2b),ZnPp(2b),CuPp(3b),CuPp(4b).On the one hand,porous spherical titania structures have been fabricated using tenplating-hydrothermal methods with the butyl titanate as raw materials.The MPp/TiO2 were obtained by loading the metalloporphyrin onto the porous spherical titania in a teflon-lined autoclave(25 mL)and kept at 150 ℃ for 48 h in an oven.On the other hand,the MPp-TiO2 was fabricated by hydrolyzation of the butyl titanate,using the metalloporphyrin as sensitizer and the morphology controlling agent.The MPp/TiO2 photocatalyst and the MPp-TiO2 have been characterized by SEM,TEM,BET,XRD,FT-IR,UV-Vis DRS and PL.Their photo catalytic activities were detected by the degradation of the 4-nitrophenol.(1)The SEM and TEM images of the porous spherical titania revealed that experimental conditions play an important role in the morphology of the TiO2.(2)The photo catalytic activity of the MPp,TiO2 is better than the MPp/TiO2,and their activity is better with the increase of carboxyl groups(ester groups)in the porphyrin molecules.This result indicates that porphyrin linked with Ti02 by the Ti-O-C=O bond.(3)The TEM images reveal that there are heterojunction structures in MPp-TiO2,which improved catalytic activity of MPp-TiO2 obviously.This result reveals the accumulated pattern of porphyrin molecules on the surface of TiO2 as well as the strength interaction between porphyrin and TiO2 play the key role in their photocatalytic activity. |
