摘要
随着经济和社会的发展，环境污染和能源短缺问题日益突出，寻找一种可持续发展的清洁能源迫在眉睫。太阳能作为一种清洁高效的能源正备受关注。而将太阳能转化为氢能的光催化分解水则被视为一种有效的途径。自1972年研究发现TiO2电极可以进行光催化分解水的反应后，光电化学池的半导体基光电极催化剂得到了广泛地关注。然而，由于TiO2固有的缺点，如电子复合率快和可见光吸收差，限制了它的进一步应用。研究者们通过不同的方法来提高半导体的催化活性，如光敏剂敏化，助催化剂修饰等，但总体来说光催化效率依然比较低。因此，新型的高效率光电极材料仍需开发。石墨烯的发现及其特殊的结构和优异的光电性能为增大电极材料的活性提供了新的思路。本论文以石墨烯为载体和电子中继体，制备了半导体功能化石墨烯的复合光催化剂，优化了复合催化剂中不同组分的组成，研究了其在半导体催化体系和光电化学池两个体系中的催化性能和反应机理。具体工作内容如下所示：
八宝汤(1) 通过一步水热合成法制备了一个由介孔三氧化钨(m-WO3)、四氧化三锰(Mn3O4)纳米粒子和氮掺杂石墨烯(NGR)组成的三组分复合物。实验中通过XRD、TEM、SEM、Raman、XPS等对复合催化剂进行了结构表征，用DRS和光电响应测试了其光电化学性质。结果显示Mn3O4纳米粒子附着在m-WO3表面，且WO3/Mn3O4复合物与NGR之间有着良好的接触。此三组分催化剂在光解水产氧的反应中展示了比单独组分更高的催化活性。当Mn3O4与NGR的掺杂量达到最佳时，其产气量为294 mol g-1。WO3与Mn3O4之间的异质结构能够有效的促进光生电子的分离和转移。NGR作为一个优异的电子接受体和中继
体对光催化的提升也起了极大的作用。最后我们对其反应机理进行了讨论。
(2) 通过水热共沉淀法制备了p型的光电阴极材料Cu掺杂的Zn x Cd1-x S半导体，用共沉淀分解法制备WO3光阳极材料，最后经过石墨烯修饰电极并将两个电极串联起来，形成了光电化学池体系。实验中通过XRD、SEM、Raman、XPS、DRS、光电化学测试等考察了两种电极材料的结构和光电性质。实验中将光电化学池体系置于紫外可见光下照射，进行了光催化分解水反应。Mott-Schottky曲线证明了Cu掺杂的Zn0.3Cd0.7S转变为了p型半导体。在反应中，Cu能够帮助光生电子的转移。最佳的
Cu含量在6%，光电化学池体系产氢和产氧量分别为459.0和86.2 μmol g-1。最后，我们同样给出了在PEC体系中的分解水机理。
(3) 通过固态源掺杂法制备了p型的光电阴极材料Cu掺杂的TiSi2半导体，用共沉淀分解法制备WO3光阳极材料，最后经过Pt纳米粒子修饰电极并将两个电极串联起来，形成了光电化学池体系。实验中通过SEM、AFM、XRD、DRS、光电化学测试等考察了两种电极材料的结构和光电性质。实验中将光电化学池体系置于紫外可见光下照射，进行了光催化分解水反应。在反应中，Pt纳米粒子能够有效的分离和收集光生电荷，降低了电子空穴的复合率。光电化学池体系产氢和产氧量分别为171和58 μmol g-1。最后，我们同样给出了在PEC体系中的分解水机理。
关键词：半导体；光电极材料；石墨烯；光催化；分解水
水的笔画顺序怎么写
作者：吴毅杰
指导老师：杨平教授
Preparation of Photoelectrode Materials in Photoelectrochemical Cell and Their Photocatalytic伤心的女人
Water Splitting Properties
Abstract
Recently, with the development of society, energy shortages and environmental issues have become increasingly prominent and thus eking for clean and sustainable energy is an urgent task. Solar energy attracts much attention and has been considered as one of the major strategies for solving the problems. Converting solar energy to hydrogen by photocatalytic water splitting ems to be an effective way. Since water splitting system bad on TiO2electrode was discovered by Fujishima in 1972, miconductor-bad photocatalytic system in photoelectrochemical cells gains its popularity. However, the intrinsic drawbacks such as fast chargerecombinationrate and low visible-light absorption limit itspractical application. Thus, many rearch groups have beenfocusing on developing novel miconductors with improved photocatalytic efficiencies, such as doping cocataly
sis and surface nsitization. The discovery of graphene has opened up a new way to enhance the photocatalytic performance due to its remarkable conductivity and superior electron mobility. In this master’s thesis, we prepared novel photoelectrode materials, using grahene as an excellent electron accepter and mediator. The photocatalytic performance of the materials was carried out in miconductor photocatalytic system and photoelectrochemical system. The transformation of photoelectrons and the propod mechanism were studied. The main points were shown as follows:
围巾的各种织法(1) A novel ternary nanocomposite comprid of mesoporous WO3, Mn3O4 nanoparticles and N-doped graphene was prepared by a one-potdeposition method. The nanocomposite was characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The results demonstrated that the Mn3O4 nanoparticles had been successfully hybridized蛋白的功效和作用
富贵逼人
with the mesoporous WO3 and the WO3/Mn3O4 hybrid was well disperd on the surface of N-doped graphene with superior interactions. The nanocomposite exhibits higher photocatalytic activity for water oxidation than the individualmesoporous WO3and WO3/Mn3O4catalysts. The amount of oxygen evolution from the optimized heterostructural photocatalyst (1.5wt% Mn3O4and 2wt% N-doped graphene) was 294 μmol g-1, which was about 3.6 times as high as that from m-WO3. The he
terostructure formed between Mn3O4and m-WO3enhances photogenerated electron/hole transfer and restrains the recombination of charges greatly. N-doped graphene in the nanocompositeacting as an excellent electron accepter and mediator also contributes to the increa of photocatalytic performance by promoting the paration and transfer of photogenerated charges. Last we offer the mechanism of oxygen production over WO3/Mn3O4/NGR photocatalyst.木瓜粉的作用与功效
(2) A p-n type photoelectrochemical tandem cell bad on p-type Cu doped Zn0.3Cd0.7S/graphene (Zn0.3Cd0.7S (Cu)/GR) photocathode and n-type WO3/graphene (WO3/GR) photoanode was successfully fabricated. Through examination of the optoelectronic and photoelectrochemicalproperties of Zn0.3Cd0.7S(Cu)/GR and WO3/GR photoelectrodes, we evaluate the feasibility of the tandem cell for overall water splitting under UV-vis (and visible) light irradiation. The Mott-Schottky analysis suggests that Cu-doped Zn0.3Cd0.7S becomes a p-type miconductor. Moreover, the Cu dopant could enhance the photogenerated electrons transfer greatly during photocatalytic process. The optimal Cu doping in Zn0.3Cd0.7S photocathode concentration was found to be 6%. As is expected, WO3 photoelectrode worked as a photoanode to produce oxygen from water. The amounts of hydrogen and oxygen evolved from this tandem cell with the optimal electrodes were 459.0 and 86.2 μmol g-1, respectively. Last we also advi the mechanism of water splitting in the PEC cell.
(3) A novel reactor bad on photoelectrochemical cell was fabricated for overall water splitting by using TiSi2 film as H2-photocatalyst, and WO3 film as O2-photocatalyst. The two films were characterized by scanning electron microscopy (SEM), atomic force
microscopy (AFM), X-ray diffraction (XRD), UV-vis diffu reflectance spectra, photoelectrical respon and electrochemical impedance spectra. The system demonstrated nice photocatalytic activity and stability for water splitting. The amount of H2and O2 evolved after 7 h irradiation was 171 μmol g-1 and 58 μmol g-1, respectively. Last we also advi the mechanism of water splitting in the PEC cell.
Keywords:Semiconductor; Photoelectrode Materials; Graphene; Photocatalytic; Water Splitting
Written by: Yijie Wu
Supervid by: Professor Ping Yang
>透水砖铺装
