| Photocatalysis is one of the efficient environmental pollution manage technology due to its environmental friendly, low energy loss and excellent photocatalytic activity. Meanwhile solar power as its potential energy source has obtained widespread attention. The core of photocatalytic technology is the photocatalyst. However, the wide researched photocatalyst based on TiO2 is beset by some problems such as the utilization limitation of visible light and low quantum efficiency, which restraining the further development of photocatasis. The order porous structure like photonic crystal (PC) could control the transmission route of light due to its special physicl chemistry performance, such as large surface area, band gap scattering effect and slow photon effect, PC structure could achieve the concentration of light and enhance the mass transfer. Carbon nitride material is belonged in unique organic polymers semiconductor, which possesses excellent light absorption and charge transfer ability. When conbined with other semiconductors to form heterojunction built could expand its visible light absorption region and improve the photo-generated carrier separation ability, thus could further enhance the photocatalytic efficiency. In this dissertation, several works have been done as follows:(1) The CdSe inverse opal photonic crystals were frabricated via the electrochemical deposition, four different particle sizes of polystyrene (PS) microspheres were utilized. The PC shows face-centered cubic structure and pore orderd arrangement. The best deposition voltage and time is -0.65 V and 3 h, the calcination temperature is 450 ℃. The band gap scattering effect and slow photon effect of PC enhance its photoresponse ability. The test indicated that CdSe-193 achieved a high photocurrent density value (8 mA/cm2) which was about 18 times higher than that of CdSe film (0.5 mA/cm2) under visible light irradiation.(2) The SL g-C3N4 was prepared by directiy thermal polymerization of melamine and ultrasonic exfoliated, the TiO2 nanoparticles were prepared by direct hydrolysis method. The SL g-C3N4/TiO2 hybrid that SL g-C3N4 doping was prepared via mixing them well-distributed, then calcination, different ratios of hybrids were prepared by adjusting the mass ratios of SL g-C3N4 and TiO2. SL g-C3N4 displayed a single layer plane structures with 0.5 nm thickness, the irregular anatase TiO2 nanoparticles were well-distributed on the surface of SL g-C3N4 or packaged them, and slight together. The photoelectrochemical tests indicated that SL g-C3N4/TiO2 hybrids showed excellent photoresponse ability, among them, FH-(1:6) achieved a higher photocurrent density value (0.04 mA/cm2) than that of other hybrids, TiO2 and SL g-C3N4, which was 10 times higher than that of TiO2. Moreover, the result of RhB photocatalytic degration under Xe lamp irradiation illustrated that hydrid FH-(1:6) which the mass ratio of SL g-C3N4 and TiO2 is 1:6 showed a better photocatalytic activity, the kinetic constant of FH-(1:6) was 3 times and 2 times than that of SL g-C3N4 and TiO2 respectively. So hydrids with SL g-C3N4 doping TiO2 enchanced full wavelength photocatalytic efficiency of TiO2. The possible photocatalytic mechanism of RhB degration was discussed.(3) The SL g-C3N4 was prepared by directiy thermal polymerization of melamine and ultrasonic exfoliated, the TiO2 nanoparticles were prepared by direct hydrolysis method. The TiO2/SL g-C3N4 hybrid that TiO2 doping was prepared via mixing them well-distributed, then calcination, different ratios of hybrids were prepared by adjusting the mass ratios of SL g-C3N4 and TiO2.SL g-C3N4 displayed a single layer plane structures, the irregular anatase TiO2 nanoparticles were well-distributed on the surface of SL g-C3N4. The photoelectrochemical and PL tests indicated that TiO2/SL g-C3N4 hybrids showed excellent photoresponse ability. The result of RhB photocatalytic degration under visible light irradiation illustrated that hydrid FH-(5:1) which the mass ratio of SL g-C3N4 and TiO2 is 5:1 showed a better photocatalytic activity, the kinetic constant of FH-(5:1) was 3.4 times than that of SL g-C3N4. So hydrids with TiO2 doping SL g-C3N4 enchanced visible light wavelength photocatalytic efficiency of SL g-C3N4. The possible photocatalytic mechanism of RhB degration was discussed.The above results of all experiments in this dissertation demonstrated that the well-designed semiconductor nanostructure like photonic crystal (PC) could achieve the concentration of light and enhance photocatalytic efficiency due to its special physicl chemistry performance; the heterojunction built between carbon nitride material and other semiconductors could expand its visible light absorption region and improve the photo-generated carrier separation ability, thus could further enhance the photocatalytic efficiency. These studies supplied feasible approaches for the modified of efficient visible light photocatalyst, and provided reference value of the further development for photocatalytical technology. |
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