氧化亚铜微晶及其复合材料的助熔剂法合成及其光催化性质的研究

发布时间：2018-04-02 03:17

  本文选题：助熔剂法　切入点：氧化亚铜微晶　出处：《吉林大学》2015年硕士论文

【摘要】：氧化亚铜(Cu2O)是一种重要的p型半导体材料，禁带宽度为2.17eV，可被波长为400-800nm的可见光激发，理论上，光电转换效率可以达到20%。它独特的光学和电学性质，使其在光催化降解废水污染物、太阳能电池和气敏传感器等方面有着广泛的应用。当Cu2O粒子的形貌、尺寸改变时，相应的光学、电学性质也会改变，所以，寻找一种简便的方法来实现形貌及尺寸的可控合成显得十分重要。 基于上述的研究思路，本论文采用固相助熔剂法，以CuO、Cu和NaOH为原料，制备了不同形貌的Cu2O微晶。系统地考察了热力学因素温度和时间对Cu2O微晶形貌的影响，，并研究了Cu2O微晶在不同形貌间的进化过程和相应的光催化性质。此外，利用同种方法制备了Cu2O/Cu复合材料，并对其相关性质进行了研究。主要研究内容如下： (1)采用固相助熔剂法，以CuO、Cu和NaOH为原料，成功制备了Cu2O微晶。详细的分析了反应温度和反应时间的变化对Cu2O微晶形貌的影响。结果表明：当反应时间固定时，可以通过改变温度来调控Cu2O微粒不同晶面的相对生长速率，从而达到形貌可控的目的。当反应时间为2h时，反应温度由250°C上升至650°C时，Cu2O微晶由八面体形貌转变为截{110}面八面体形貌，最后到菱形十二面体形貌。当反应温度固定时，反应时间的改变同样可以影响Cu2O微晶的形貌。反应温度固定为650°C，反应时间为2h，Cu2O微晶为菱形十二面体结构。而当反应时间增长至6h时，Cu2O微晶的形貌演变为截{111}面菱形十二面体。 (2)分别对得到的四种不同形貌的Cu2O微晶进行了光催化降解甲基橙(MO)水溶液能力的测试。实验结果表明它们的光催化降解能力强弱顺序为：菱形十二面体截{111}面菱形十二面体截{110}面八面体八面体。菱形十二面体Cu2O微晶，在可见光（钨灯）照射下，降解5mol/L的甲基橙溶液，在8h内降解率达到73%。这与它的{110}晶面有关。 (3)利用固相助熔剂法，成功合成Cu2O/Cu复合材料。扫描电镜表征结果为，Cu2O/Cu复合材料中Cu2O为菱形十二面体微晶，而Cu为微球，微球与菱形十二面体接触。光催化实验结果表明，在光催化降解相同浓度甲基橙(MO)溶液时，Cu2O/Cu复合材料的催化活性略好于菱形十二面体结构的Cu2O微晶。针对这一结果，尝试对Cu2O/Cu光催化机理做出了相关讨论：复合材料独特的结构使得光生电子和光生空穴复合过程被抑制，光催化性能得到提高。
[Abstract]:Cuprous oxide (Cu2OO) is an important p-type semiconductor material with a band gap of 2.17eV, which can be excited by visible light with wavelength of 400-800nm. In theory, the optoelectronic conversion efficiency can reach 20g. It has unique optical and electrical properties. It has a wide range of applications in photocatalytic degradation of wastewater pollutants, solar cells and gas sensors. When the morphology and size of Cu2O particles change, the corresponding optical and electrical properties will also change, so, It is very important to find a simple method to realize the controllable synthesis of morphology and size. Based on the above research ideas, Cu2O microcrystals with different morphologies were prepared by solid flux method using CuOO Cu and NaOH as raw materials. The effects of temperature and time of thermodynamic factors on the morphology of Cu2O microcrystals were systematically investigated. The evolution process and photocatalytic properties of Cu2O microcrystals among different morphologies were studied. In addition, Cu2O/Cu composites were prepared by the same method and their related properties were studied. The main contents are as follows:. (1) Cu2O microcrystals were successfully prepared by solid flux method using CuOO Cu and NaOH as raw materials. The effects of reaction temperature and reaction time on the morphology of Cu2O microcrystals were analyzed in detail. The results showed that the reaction time was fixed. The relative growth rate of different crystal planes of Cu2O particles can be controlled by changing the temperature, so that the morphology can be controlled. When the reaction time is 2 h, When the reaction temperature increased from 250 掳C to 650 掳C, the morphology of Cu2O microcrystal changed from octahedron to truncated {110} -plane octahedron, finally to the rhombic dodecahedron. When the reaction temperature was fixed, The change of reaction time can also affect the morphology of Cu2O microcrystal. The reaction temperature is fixed at 650 掳C and the reaction time is 2 h. The crystal structure of Cu2O is rhombic dodecahedron. When the reaction time increases to 6 h, the morphology of Cu2O microcrystal evolves into a truncated {111} rhombic dodecahedron. (2) the photocatalytic degradation ability of four Cu2O microcrystals with different morphologies was tested. The results showed that the order of photocatalytic degradation was as follows: rhombohedral dodecahedron {111} rhombohedral rhombohedral. Shape dodecahedron octahedron octahedron. Rhombic dodecahedron Cu2O microcrystals, Under the irradiation of visible light (tungsten lamp), the degradation rate of methyl orange solution which degrades 5mol/L reaches 73% within 8 hours, which is related to its {110} crystal plane. (3) Cu2O/Cu composites were successfully synthesized by solid flux method. The results of scanning electron microscopy showed that Cu2O was a rhombic dodecahedron, while Cu was a microsphere, which was in contact with a rhombohedral dodecahedron. The catalytic activity of Cu _ 2O / Cu composite is slightly better than that of Cu2O microcrystals with diamond dodecahedron structure when the photocatalytic degradation of the same concentration of methyl Orange MO-O solution is carried out. The photocatalytic mechanism of Cu2O/Cu was discussed in this paper. The unique structure of the composites inhibited the photoelectron and photogenerated hole recombination process and improved the photocatalytic performance.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB333;O614.121

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