稀土钆、钇掺杂二氧化钛纳米管光致发光及光催化性能的研究

发布时间：2018-03-04 17:10

本文选题：稀土掺杂　切入点：TiO2　出处：《重庆大学》2015年硕士论文　论文类型：学位论文

【摘要】：半导体的光催化性能在太阳能和环保中有广阔的应用前景。其中Ti O2具有无毒、价格低廉、抗光腐蚀以及稳定的化学性质而备受研究者青睐。但对于纯的纳米Ti O2而言,在光催化过程中存在激发的电子-空穴对容易复合、太阳能利用率等缺点,降低了其光催化效率,严重限制其广泛应用。为提高Ti O2的光催化性能,对纳米Ti O2进行改性成为研究热点。稀土元素通过提高纳米Ti O2的氧空穴和缺陷浓度、降低电子和空穴的复合率,进而提高光催化性能。另外相对Ti O2纳米粉而言,纳米管具有更大的比表面积,因而具有优异的光催化性能。以上原因使得研究稀土掺杂的Ti O2纳米管对提高其光催化性能具有重要意义。本文采用溶胶-凝胶法制备不同温度煅烧及稀土Gd、Y掺杂的Ti O2纳米粉,并以此为前驱物,利用微波水热合成法制备相应的Ti O2纳米管。采用场发射扫描电镜(FESEM),场发射透射电镜(FETEM),X射线衍射仪(XRD)和荧光光谱仪(FS)对样品进行表征。考察微波水热合成法对Ti O2纳米粉晶型、形貌和结晶度的影响以及稀土Gd、Y不同掺杂量对Ti O2纳米粉及纳米管形貌、结晶度、光致发光性能和光催化性能的影响。结果表明,煅烧温度的提高使Ti O2纳米粉晶粒粒径增大。以不同温度煅烧纳米粉为前驱物,微波水热合成法制备的Ti O2纳米管形貌基本不发生变化。另外微波水热合成法能使600℃和700℃煅烧的Ti O2由锐钛矿向金红石转变,而500℃煅烧的Ti O2的晶型未发生变化。稀土Gd、Y元素的掺杂含量直接影响Ti O2纳米粉粒径大小。随着掺杂Gd、Y掺杂量的增加,其粒径均不同程度的减小。掺杂2%的Gd或Y元素的Ti O2纳米粉粒径最小,分别达到10.3nm和9.3nm。而稀土Gd、Y元素掺杂对Ti O2纳米管的形貌影响不大。另外其结晶度随着Gd、Y元素掺杂含量的增加而降低,适当掺杂Gd、Y元素有助于纳米管保持一定的结晶度,其原因有待进一步探究。掺杂的Gd、Y元素可进入纳米Ti O2晶格中,导致氧空穴和缺陷浓度变化,其光致发光性能随着掺杂含量的增加,呈现先增加后降低的变化趋势。实验结果表明,对于掺杂稀土Gd元素的Ti O2纳米粉,Gd含量为0.5%时FS强度最大;含量为0.2%和0.5%时纳米管的FS强度最大。对于掺杂稀土Y元素的Ti O2纳米粉,Y含量为0.5%时FS强度最大;含量为1%时纳米管的FS强度最大。掺杂稀土Gd、Y可提高氧空穴和缺陷浓度,降低电子-空穴对复合,从而明显提高纳米Ti O2的光催化性能。对比纯的Ti O2纳米粉,掺杂稀土Gd、Y的Ti O2纳米粉光催化性能分别提高44.7%和40%。对比纯的Ti O2纳米管,掺杂稀土Gd、Y光催化性能的Ti O2纳米管光催化性能分别提高71%和27.7%。其中掺杂Gd和Y的Ti O2纳米粉和纳米管的光催化性能最佳值的掺杂量均在0.5%和1%取得。掺杂Gd,Y元素的纳米Ti O2的荧光光谱和光催化性能的变化趋势一致,但最优掺杂含量值不同。表明光致发光性能可以大致快速评估分别掺杂Gd、Y元素的纳米Ti O2的光催化性能,但其缺乏精确评估能力。
[Abstract]:The photocatalytic properties of semiconductors have broad application prospects in solar energy and environmental protection. The Ti O2 is non-toxic, low price, light corrosion and anti chemical properties stable and has attracted great attention from researchers. But for the pure nano Ti O2, existing electronic - excited hole on the composite in the photocatalytic process disadvantages of solar energy utilization rate, reduce the photocatalytic efficiency, and its wide application severely limited. In order to improve the photocatalytic performance of Ti O2, O2 of nano Ti was modified to become a research hotspot. Rare earth elements by increasing the oxygen vacancies and defects of nano Ti O2 concentration, reduce the recombination rate of electron and hole, and then improve the the photocatalytic properties of O2 nanometer powder relative to Ti. In addition, nanotubes with larger specific surface area, so it has excellent photocatalytic properties. The above reasons make the study of rare earth doped Ti O2 nanotubes to improve its photocatalytic performance Is of great significance. This paper prepared different calcination temperatures and rare earth Gd by sol-gel method, Ti doped O2 nano powder Y, and as a precursor, using microwave hydrothermal synthesis of the corresponding Ti O2 nanotubes. By field emission scanning electron microscopy (FESEM), field emission transmission electron microscopy (FETEM), X ray diffraction (XRD) and fluorescence spectrometer (FS) were used to characterize the samples. The effects of microwave hydrothermal synthesis of Ti nano O2 powder, affect the morphology and crystallinity of rare earth Gd and Y, different doping amount on Ti O2 nanoparticles and nanotubes morphology, crystallinity, influence the photoluminescence properties and photocatalytic properties the results show that with the increase of calcination temperature of Ti O2 nano powder particle size increases. The calcination temperature of nano powder as precursor, O2 morphology of Ti nanotubes prepared by microwave hydrothermal synthesis did not change basically. In addition the microwave hydrothermal method "can make 600 DEG C and 700 Change of calcined Ti O2 from anatase to rutile, crystal type and 500 8C Ti O2 did not change. Gd rare earth doping content of Y elements directly affect Ti O2 nano powder particle size. With the doping of Gd, the increase of Y content, the particle size was reduced in different degree. Ti O2 nano powder or Gd doped Y 2% of the smallest size reached 10.3nm, and 9.3nm. and rare earth Gd respectively, Y had little impact on the morphology of Ti doped O2 nanotubes. In addition, the crystallinity increased with Gd, Y doping decreased, appropriate doping Gd, Y elements can help keep the nanotubes the crystallinity, the reasons need to be further explored. The doping of Gd, Y elements can enter Ti nanoparticles in the O2 lattice, resulting in oxygen vacancies and defects concentration, the photoluminescence properties with increasing doping content, showed a trend of first increase and then decrease. The experimental results show that the doping of rare Ti O2 nano powder soil element Gd, Gd content is FS the maximum intensity of 0.5%; content of FS strength of 0.2% and 0.5%. The maximum for Ti nanotubes O2 nano powder doped with rare earth elements Y, Y content is FS the maximum intensity of 0.5%; content of FS 1% nanotubes. The maximum intensity of rare earth doped Gd. Y can increase the oxygen vacancies and defects concentration, reduce the recombination of electron hole, thereby significantly improve the photocatalytic performance of nano Ti O2. Compared with the pure Ti nano O2 doped rare earth Gd, Ti nano O2 photocatalytic performance of Y and 40%. were increased by 44.7% compared with the pure Ti O2 nanotubes, rare earth doped Gd. The photocatalytic performance of Ti nano O2 photocatalytic performance of Y tube are respectively 71% and 27.7%. increased the amount of doping which optimum photocatalytic properties of doped Gd and Y Ti of O2 nanoparticles and nanotubes were achieved in 0.5% and 1%. Gd doped, changes of fluorescence spectrum and photocatalytic activity of nano Ti O2 Y element to the The trend is the same, but the best doping content is different. It indicates that the photoluminescence properties can roughly evaluate the photocatalytic properties of nano Ti O2 doped with Gd and Y elements, but it lacks precise evaluation ability.

【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O614.411;TB383.1

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