碳基高效扩散光电极的制备及对苯甲醛催化降解性能研究

发布时间：2018-03-18 08:31

  本文选题：水热法　切入点：介孔TiO_2　出处：《吉首大学》2016年硕士论文　论文类型：学位论文

【摘要】：基于空气质量的日益恶化,光催化技术在空气净化方面得到了广泛的发展。其中,TiO_2由于具有氧化性强、价格低廉、性能稳定和易于改性等优势,在空气治理方面具有很大的研究潜能。因此,本文对TiO_2光电极的制备、改性及机制进行了探讨,主要内容如下:以十六烷基三甲基溴化铵为液晶模板,四氯化钛为钛源,导电碳毡为载体,通过超声波辅助水热法(Ultrasound-assisted hydrothermal method,UH)制备介孔二氧化钛/导电碳毡(Mesoporous titania/conductive carbon felt,MPT/CCF)复合光电极材料(UH-MPT/CCF),利用X-射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、傅里叶红外(FT-IR)、N_2吸附-脱附、热重-差热(TG-DTA)等方法对样品结构进行表征。结果表明,介孔化处理提高了UH-MPT/CCF光电极的比表面积,增加了活性中心(·OH和Ti3+),TiO_2固载化提高了对目标降解物的吸附和表面电子转移,协同偏电压促进光生电子-空穴对的分离。在多方的协同作用下UH-MPT/CCF对苯甲醛在100 min内降解率为83.9%,分别是水热法制备介孔二氧化钛/导电碳毡(H-MPT/CCF)、无孔二氧化钛/导电碳毡(No porous titania/conductive carbon felt,NPT/CCF)和P25/CCF的1.38、1.75和2.38倍。此外,采用相同的制备工艺,分别制备了导电碳毡负载铂掺杂介孔TiO_2光电极(MPT-Pt/CCF)、导电碳毡负载锰掺杂介孔TiO_2光电极(MPT-Mn/CCF)、导电碳毡负载铁掺杂介孔TiO_2光电极(MPT-Fe/CCF)和导电碳毡负载锌掺杂介孔TiO_2光电极(MPT-Zn/CCF)。结果表明,金属Pt离子的掺杂能引入了杂质能级,减小TiO_2的能带隙,同时,Pt充当光生电子-空穴捕获阱,阻止电子-空穴对的复合,使得MPT-Pt/CCF具有更高的光电催化效率。最后,以气相苯甲醛为目标降解物,探讨了MPT/CCF系列光电极的光电催化性能及其对气相苯甲醛的降解机理。根据GC/MS结果分析,提出了气相苯甲醛的降解机制。同时,得出光电极材料的最佳制备工艺条件是2次负载500℃煅烧,最佳的降解条件为温度35℃、相对湿度55%、偏电压10 V、初始浓度40 mg/m3、电极间距20 cm。
[Abstract]:Due to the deterioration of air quality, photocatalytic technology has been widely developed in air purification, among which TiO-2 has the advantages of strong oxidation, low price, stable performance and easy modification. Therefore, the preparation, modification and mechanism of TiO_2 photoelectrode are discussed in this paper. The main contents are as follows: cetyltrimethylammonium bromide as liquid crystal template, titanium tetrachloride as titanium source, hexadecyltrimethylammonium bromide as liquid crystal template, titanium tetrachloride as titanium source, Conductive carbon felt was prepared by ultrasonic assisted hydrothermal method (UH). The composite photoelectrode material, UH-MPT / CCF, was prepared by ultrasonic assisted hydrothermal method (UH). The composite photoelectrode material, UH-MPT / CCF, was adsorbed and desorbed by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), FT-IRT / N2. The results showed that mesoporous treatment increased the specific surface area of UH-MPT/CCF photoelectrode, and increased the active center (路OH and Ti3) tio _ 2 immobilization, which increased the adsorption and surface electron transfer of the target degradation, and the structure of the sample was characterized by thermogravimetry and differential thermogravimetric TG-DTA.The results showed that the mesoporous treatment increased the specific surface area of the photoelectrode, and increased the active center (路OH and Ti3 / TiO2). The synergistic bias voltage promotes the separation of photogenerated electron-hole pairs. The degradation rate of benzaldehyde by UH-MPT/CCF in 100 min is 83.9%. The mesoporous TIO _ 2 / conductive carbon felts prepared by hydrothermal method is H-MPT / CCF _ (2), no porous titanium dioxide / conductance. Carbon felt No porous titania/conductive carbon feltr NPT / CCF and P25 / CCF 1.38% and 2.38 times. Using the same preparation process, Conductive carbon felts supported on platinum-doped mesoporous TiO_2 photoelectrodes, conductive carbon felts supported on manganese doped mesoporous TiO_2 photoelectrodes, conductive carbon felts supported iron doped mesoporous TiO_2 photoelectrodes (MPT-Fe / CCFF) and conducting carbon felts supported zinc doped mesoporous TiO_2 photoelectrodes were prepared. The results show that, The doping energy of metal Pt ion introduces impurity energy level, reduces the energy band gap of TiO_2, while Pt acts as photogenerated electron-hole trapping trap, which prevents the recombination of electron-hole pair, which makes MPT-Pt/CCF have higher photocatalytic efficiency. The photocatalytic performance of MPT/CCF series photoelectrode and its degradation mechanism of gaseous benzaldehyde were discussed. Based on the analysis of GC/MS results, the degradation mechanism of gaseous benzaldehyde was proposed. The optimum preparation conditions of photoelectrode materials were obtained as follows: twice calcined at 500 鈩，

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