WO_x和MoO_x材料的制备、表征及光电化学应用

发布时间：2018-05-22 11:18

  本文选题：WO_x(W_(18)O_(49)) + MoO_x(Mo_4O_(11))　； 参考：《北京交通大学》2017年硕士论文

【摘要】：现代社会人类面临着环境污染和能源短缺的两大挑战。半导体光催化技术和染料敏化太阳能电池(Dye-sensitized solar cell,DSSC)是解决环境和能源危机的有效途径。传统的Ti02光催化剂带隙较宽、光催化活性低;DSSC对电极使用贵金属Pt难以产业化,上述问题使得光催化技术和DSSC发展受到了阻碍。非化学计量比的W_(18)O_(49)是单斜结构,电子能级带隙较窄,对太阳光有较好的响应,且具有优良的导电性能,适用于半导体光催化等领域。非化学计量比的钼氧化物具有多价态,在应用过程中多个价态变换,表现出较强的化学活性和较好的电子传输性能,尤其是Mo_4O_(11),电阻率较小(10-4Ω·cm),具有更好的传输性能,是理想的光催化媒介和光阴极材料。因此,本论文首次对三维有序大孔(Three-dimentional ordered macroporous,3 DOM)结构的WO_x材料进行了表面性能表征,并制备出高Mo_4O_(11)含量、可见光吸收性能优异的MoO_x材料,详细开展了以下研究工作:(1)采用无乳液聚合法合成出不同粒径的单分散PMMA微球;利用离心法和恒温水浴成膜法组装PMMA微球得到有序排列的胶体晶体模板。使用三氧化钨的氢氟酸溶液浸泡PMMA胶体晶体模板,经过干燥、煅烧后得到WO_x 3DOM材料。利用SEM、XRD、XPS、Raman和UV-vis吸收光谱等手段对材料进行表征。(2)采用溶剂热法,改变溶剂和WC16溶液的浓度,制备出纳米线、梭形、海胆状的W18049纳米材料,利用SEM和XRD对材料进行表征。使用制备的W_(18)O_(49)纳米材料作光催化剂,在紫外-可见光照射下降解甲基橙,结果表明:纳米线和梭形W_(18)O_(49)对甲基橙的降解效果较好,最高降解效率分别达到94%和100%。(3)采用不同工艺制备MoO_x材料,研究了工艺条件对MoO_x的相组成及相含量的影响。①将钼酸铵直接在5vol%H_2/Ar气氛下热解还原,在600℃下保温2h得到的MO_4O_(11)含量最高(84.8%)。②使用水热法合成带状三氧化钼,然后三氧化钼在5vol%H_2/Ar气氛下还原,在 600℃下保温2h得到的Mo_4O_(11)含量最高(92%)。③将钼酸铵在空气中煅烧,在650℃下保温5h得到三氧化钼,然后三氧化钼在5 vol%H_2/Ar气氛下还原,在625℃下保温2h得到Mo_4O_(11)含量高达98.5%。利用SEM、XRD、XPS、Raman和UV-vis吸收光谱等方法对MoO_x材料进行表征。使用制备的MoO_x材料作光催化剂,在紫外-可见光照射下降解罗丹明B,结果表明:98.5%Mo_4O_(11)含量的MoO_x材料的降解效率最高(97%)。使用Mo_4O_(11)作DSSC对电极得到了初步电池性能结果。
[Abstract]:In modern society, human beings are faced with two major challenges of environmental pollution and energy shortage. Semiconductor photocatalytic technology and Dye-sensitized solar cell DSSC are effective ways to solve the environmental and energy crisis. The traditional Ti02 photocatalyst has wide band gap and low photocatalytic activity. It is difficult to industrialize using noble metal Pt for photocatalytic activity. These problems hinder the development of photocatalytic technology and DSSC. The non-stoichiometric WSCL _ (18) O / O _ (49) has a monoclinic structure, narrow band gap of electronic energy levels, good response to solar light, excellent conductivity, and is suitable for semiconductor photocatalysis and so on. Molybdenum oxides with non-stoichiometric ratio have multivalent states, and in the process of application, they exhibit stronger chemical activity and better electron transport performance, especially for Mo _ 4O _ S _ (11), resistivity is 10 ~ (-4) 惟 cm ~ (-1), and it has better transport performance. It is an ideal photocatalytic medium and photocathode material. Therefore, for the first time, the surface properties of three-dimentional ordered macroporous3DOM-based WO_x materials with three dimensional ordered macroporous structure have been characterized, and MoO_x materials with high Mo4O structure and excellent visible light absorption have been prepared. The following research work was carried out in detail: (1) Mono-dispersed PMMA microspheres with different particle sizes were synthesized by non-emulsion polymerization, and PMMA microspheres were assembled by centrifugal method and isothermal water bath film forming method to obtain ordered colloidal crystal templates. The PMMA colloidal crystal template was soaked in the hydrofluoric acid solution of tungsten trioxide, and the WO_x 3DOM material was obtained after drying and calcining. The nanocrystalline, fusiform and sea urchin W18049 nanomaterials were prepared by means of solvothermal method, changing the concentration of solvent and WC16 solution, and characterized by SEM and XRD. The photocatalytic degradation of methyl orange by using the prepared WSP _ 18O _ S _ (49) nanomaterials under ultraviolet and visible light irradiation showed that nanowires and fusiform Washi-18o _ s _ (49) had better degradation effect on methyl orange, and the results showed that the degradation of methyl orange by nanowires and fusiform Wsn _ (18) O _ (O) was better. The highest degradation efficiency reached 94% and 100% respectively) MoO_x materials were prepared by different processes. The effects of process conditions on the phase composition and phase content of MoO_x were studied. 1 ammonium molybdate was pyrolyzed and reduced directly in 5vol%H_2/Ar atmosphere. Molybdenum trioxide was synthesized by hydrothermal method, then reduced in 5vol%H_2/Ar atmosphere, and Mo4OOT11 obtained by heat preservation at 600 鈩，

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