| 题名 | 纳微结构光催化剂合成及还原水制氢气研究 |
| 作者 | 李翠霞 |
| 学位类别 | 博士 |
| 答辩日期 | 2013-05-01 |
| 授予单位 | 中国科学院研究生院 |
| 导师 | 张锁江 |
| 关键词 | 半导体光催化 纳微结构 形貌控制 还原水 氢气 |
| 其他题名 | Synthesis and Properties of Micro/nano Structured Photocatalysts toward Water Reduction for Hydrogen |
| 学位专业 | 应用化学 |
| 中文摘要 | 能源短缺和环境污染是影响人类可持续发展的重要问题。为此，开发可再生的低碳能源是很迫切的任务。通过光催化分解水反应过程，将太阳能转化为以氢气为载体的化学能，是可再生能源利用的有效途径。光解水制氢过程实用化的关键是构筑高效稳定的可见光催化剂。 本文针对太阳能光催化分解水这一课题，通过金属硫化物半导体纳微结构的合成与构筑，系统研究了新型可见光光催化剂的结构与性能间的关系，主要研究工作及创新性成果如下： (1) 通过水热法大量合成了二维CdS纳微树叶。其直径为4~6 μm、厚度为30~50 nm。叶子表面平滑，由台阶状的平行薄片层组成。SAED与HRTEM图像表明叶子的表面主要由(0001)高能晶面组成，并且叶子局部呈单晶结构。研究了氢氟酸(HF)与原料浓度、反应温度、反应时间对产物的影响，实验表明通过调节氢氟酸和原料的浓度可以控制产品的形貌。根据六方相CdS的晶体结构和氢氟酸选择性吸附过程，提出了晶体生长机理。 这种CdS纳微树叶具有显著增强的光催化还原水产氢气活性。在没有任何贵金属助催化剂时，CdS纳微树叶产氢速率为740.9 μmol?h-1，约为CdS球形微粒的6.2倍。CdS纳微树叶光催化活性的增强可归因于其高结晶度、(0001) 高能晶面暴露、宽的禁带宽度以及薄片状形貌。优化了催化剂浓度、牺牲剂种类与浓度等光催化反应条件。通过对CdS纳微树叶进行贵金属(Pt, Au)负载，进一步提高了其光催化产氢活性。 (2) 通过水热和溶剂热方法制备了一系列纳米尺寸ZnxCd1-xS (x=0-1) 固溶体，系统研究了Zn/Cd元素组成对固溶体晶体结构和禁带宽度的影响。然后固定Zn/Cd元素比为1:1，分别在醇类和胺类溶剂中合成了Zn0.5Cd0.5S固溶体，研究了溶剂种类和配比对产物结构和性质的作用。在醇水类溶剂中得到近似球形纳米粒子，而在胺类溶剂中得到一维纳米结构。其中，乙二胺和乙二醇体系得到的Zn0.5Cd0.5S为高结晶度的立方相结构。此外，通过调节混合溶剂中乙二胺与水的体积比，可以控制产物的比表面积。 研究了不同溶剂中所得固溶体的光催化产氢活性，顺序如下：Zn0.5Cd0.5S(EN) > Zn0.5Cd0.5S(EG) > Zn0.5Cd0.5S(DETA) > Zn0.5Cd0.5S(water) > Zn0.5Cd0.5S(ethanol) > Zn0.5Cd0.5S(HH)。乙二胺体系中合成的Zn0.5Cd0.5S固溶体光催化剂产氢活性最高，乙二醇体系中Zn0.5Cd0.5S光催化产氢活性次之。 (3) 通过离子液体作为溶剂或结构导向剂，合成了其它新型的纳米光催化材料。 通过离子热/水热方法，在[Bmim][BF4]-水双相乳液中合成了六方晶相三元金属硫化物ZnIn2S4。研究了[Bmim][BF4]、水含量、锌源、反应温度和时间对产物结构和性质的影响。少量水的存在是合成ZnIn2S4的关键。[Bmim][BF4]使ZnIn2S4沿(001)晶向择优生长，并导致(003) 峰位置向低角度方向微移。通过控制反应条件，可以选择性制备ZnIn2S4球形纳米粒子、微球、或三维花状结构。从含有[Bmim][BF4]的介质中得到的ZnIn2S4禁带宽度变大。 发明了一种离子液体辅助水热合成Bi2WO6?纳米材料的方法。反应体系采用了阴离子为[BF4]-的咪唑类离子液体，分别为不同烷基链长的[Cnmim][BF4](n=4, 16)和羧基功能化的[Acmim][BF4]离子液体。通过水热晶化过程，得到了具有较高分散性的Bi2WO6材料，且材料光催化降解RhB活性增强。 |
| 英文摘要 | The energy and environment crisis of modern society has made people pay more attention to renewable carbon-neutral energy. Using sunlight to generate hydrogen by water splitting is undoubtedly one of the most attractive routes for the renewable energy utilization since it converts sustainable solar energy into the cleanest chemical energy. The development of highly efficient and stable visible light photocatalyst was essential for the industrial application of photocatalytic water splitting technology. In this dissertation, we design and fabricated the micro/nano structured mental sulfide semiconductors. Their photocatalytic properties toward water reduction for hydrogen evolution were studied. Systematic research has been done on the relationship between the structure and property of the photocatalyst. The main work was as follows: (1) Two-dimensional CdS micro/nano leaves have been synthesized via a controlled hydrothermal process. The dimension of the leaves is in the range of 4-6 ?m and the thickness of the leaves is 30-50 nm. The surface of leaves is smooth and composed of several parallel laminar layers with multi-steps. The SAED and HRTEM images indicated that the surface of the leaves was mainly composed of (0001) plane and all the leaves had single-crystallinity. The morphology of the as-prepared products could be controlled by adjusting the concentration of hydrofluoric acid (HF). The effects of HF concentration, reaction temperature and time were investigated. And the possible formation mechanism is proposed based on the intrinsic crystal structure and selected adsorption process. In addition, the as-prepared CdS pinnate leaves showed enhanced photocatalytic acitivity toward hydrogen evolution under visible light irradiation. The efficiency of mico/nano leaves increased more than 6 times than normal CdS microparticles. The enhanced photocatalytic activity of CdS micro/nano leaves can be attributed to its high crystallinity, the exposed (0001) high surface energy plane and wider bandgap, as well as the thin flake-like morphology. And the photocatalytic reaction condition (including the catalyst concentration, the sacrificial species and concentration) was optimized. Furthermore, noble metal (Pt, Au) was loaded on CdS micro/nano leaves via photo deposition method. Highly dispersed Au nanoparticles with uniform size were loaded on the surface of CdS micro/nano leaves, which greatly enhanced their photocatalytic activity toward hydrogen evolution. |
| 语种 | 中文 |
| 公开日期 | 2014-05-23 |
| 页码 | 117 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/8248]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 李翠霞. 纳微结构光催化剂合成及还原水制氢气研究[D]. 中国科学院研究生院. 2013. |
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