Knowledge Management System Of Institute of Oceanology, Chinese Academy of Sciences
|Alternative Title||Study on the Mechanism of Photoinduced Cathodic Protection and Photocatalysis of Transition Metal Ⅵ-Group Compounds Enhanced by Multiphase Heterojunction System|
|Place of Conferral||中国科学院海洋研究所|
|Keyword||多相异质结 过渡金属Ⅵ族化合物 光致阴极保护 光催化 光电化学|
4. 对部分Cd基硫化物（CdS等）进行相关的改性，并探究其增强的光催化和光电化学性能，为进一步开发和设计高效的多相异质结体系打下基础。其一，通过制备镁掺杂CdS纳米棒（MgCdS），研究了其能带结构和光催化降解性能。结果表明，镁的掺杂拓宽了CdS纳米棒的带隙宽度，使得其光生电子和空穴的复合速率得到有效抑制，从而使得其光催化性能得到提高。其二，通过溶剂热法制备了一种新颖的三维海绵状CdS薄膜光电极，并研究其光电化学性能。光电化学性能测试结果表明，具有微孔海绵结构的CdS薄膜光电极具有优异的光电化学性能和光致阴极保护性能，同时具有很高的稳定性。其三，制备一种新颖的三维纳米花状Co9S8分级结构，并进一步在其表面沉积CdS纳米颗粒，成功构建Co9S8/CdS Z型异质结光催化体系。研究表明， CdS纳米颗粒均匀的分布于分级结构Co9S8表面形成Z型异质结，并协同分级结构提供大量活性位点的作用，有助于光生载流子快速的溢出，从而加速了Co9S8/CdS Z型光催化剂的光催化反应进程。
The basic principle of photoelectrochemistry, photoinduced cathodic protection and photocatalysis technology is to convert light energy into electrical energy or chemical energy. As a green technology with high efficiency, environment friendly and energy saving, the photoelectric conversion technology shows great potential during the high peak of interdisciplinary research, therefore it is favored by researchers from different areas. As an important part, the development and design of semiconductor materials has attracted the focus of scientific researchers. Multiphase heterojunction can effectively improve the performance of semiconductor materials, which is mainly due to the extended spectral absorption, the effective separation of photogenerated electron-hole pairs and the rapid transmission of photogenerated charge carriers. This paper focuses on the establishment of effective heterogeneous heterojunction system based on the common transition metal VI-group compounds, and further explores the methods and mechanism to effectively improve the photoinduced cathodic protection and photocatalytic performance. In addition, this paper also carried out the modification of Cd-based sulfides and their photocatalytic and photoelectrochemical properties, which laid a foundation for the further development and design of efficient heterogeneous heterojunction system for photoinduced cathodic protection. The detailed research contents are as follows.
1. A novel TiO2/MgTixOy multiphase heterojunction film was constructed to explore the photoinduced cathodic protection performance for 304 stainless steel. Physical characterization results show that MgTixOy was successfully coated on the nozzle surface of TiO2 nanotube array and a heterogeneous heterojunction system was formed. The scanning Kelvin probe technique was performed to test the surface potential distribution and work function of the prepared photoelectrode for the first time. The lower surface work function of the TiO2/MgTixOy film indicates the electrons are easier to escape, which increases the concentration of photogenerated charge carriers. Further photoinduced cathodic protection test results show that the photoinduced cathodic protection performance and stability of TiO2/MgTixOy multiphase heterojunction film is significantly enhanced compared with those of TiO2 film. The establishment of multiphase heterojunction effectively inhibits the recombination of photogenerated charge carriers and accelerates their separation. Therefore, the TiO2/MgTixOy multiphase heterojunction film shows significantly enhanced photoinduced cathodic protection and stability.
2. TiO2/MgTixOy multiphase heterojunction films have significantly enhanced photoinduced cathodic protection performance and long-term stability. However, the excess photogenerated electrons generated by TiO2/MgTixOy heterojunction films are difficult to ensure the continuous protection of the metal by the photoelectrode in the dark state. A novel three-dimensional hierarchical structure WO3 photoelectrode was prepared by solvothermal method, and ZnO was deposited on its surface by electrochemical method. Through further annealing, WO3/ZnWO4/ZnO multiphase heterojunction photoelectrode was successfully prepared, and its photoinduced cathodic protection performance was further explored. The results show that the establishment of multiphase heterojunction system forms a good energy band gradient, which accelerates the separation efficiency of photogenerated charge carriers and promotes the directional transmission of photogenerated electrons. Therefore, the photoinduced cathodic protection performance of WO3/ZnWO4/ZnO is significantly improved compared with those of WO3 and ZnO. At the same time, due to the coexistence of W6+ and W5+ in the multiphase heterojunction system, WO3/ZnWO4/ZnO photoelectrode has a certain electron storage capacity, which endows it with long-term and effective photoinduced cathodic protection.
3. Z-Scheme photocatalytic system can ensure the negative conduction band potential of semiconductor materials to participate in photocatalytic reaction. A Z-scheme heterojunction photocatalyst, g-C3N4/CNTs/CdZnS with carbon nanotubes (CNTs) as intermediate electron transporter between g-C3N4 and CdZnS, was designed, and its photocatalytic hydrogen production performance was investigated. The results show that the photocatalytic hydrogen production performance and stablity of g-C3N4/CNTs/CdZnS is significantly enhanced compared with those of single-phase g-C3N4, CdZnS and two-phase g-C3N4/CdZnS photocatalysts. The enhanced photocatalytic hydrogen production performance of g-C3N4/CNTs/CdZnS is attributed to the fact that CNTs, as an intermediate electron medium, can accelerate the recombination of the photogenerated holes in the valence band of g-C3N4 with the photogenerated electrons in the conduction band of CdZnS, which makes it easier for photogenerated electrons to escape from the surface of Z-scheme photocatalyst, makes the concentration of photogenerated carriers charge stronger, and prolongs the life of the photogenerated charge carriers. This novel photocatalytic system can provide a theoretical basis for the development and design of long-term photoinduced cathodic protection system.
4. Some Cd-based sulfides, such as CdS, was modified and explored to enhance the photocatalytic and photoelectrochemical properties, which will lay a foundation for the further development and design of efficient heterogeneous heterojunction system. Firstly, the energy band structure and photocatalytic degradation properties of Mg doped CdS nanorods (MgCdS) was studied. The results show that the doping of Mg element widens the band gap width of CdS nanorods, effectively inhibits the recombination of photogenerated electrons and holes, and improves its photocatalytic performance. Secondly, a novel three-dimensional spongy CdS thin film photoelectrode was prepared by solvothermal method, and its photoelectrochemical properties were studied. The results show that the CdS thin film photoelectrode with microporous sponge structure has excellent photoelectrochemical properties and photoinduced cathodic protection performance, and the stability is also greatly improved. Microporous sponge structure can significantly improve the utilization and conversion efficiency to simulated sunlight, so as to improve its photoelectrochemical properties. Thirdly, a novel three-dimensional nano flower like Co9S8 hierarchical structure was prepared with CdS nanoparticles further deposited on its surface, and Co9S8/CdS Z-scheme heterojunction photocatalytic system was successfully constructed. The results show that the photocatalytic performance of the hierarchical Co9S8/CdS heterojunction photocatalyst is significantly improved. The CdS nanoparticles evenly distribute on the surface of the hierarchical Co9S8 to form Z-scheme heterojunction, and cooperate with the hierarchical structure to provide a large number of active sites, which is conducive to the rapid transfer of photogenerated charge carriers, thus accelerating the photocatalytic reaction process of Co9S8/CdS Z-scheme photocatalyst.
|MOST Discipline Catalogue||理学::海洋科学|
|Funding Project||Qingdao Innovative Leading Talent Foundation[15-10-3-15-(39)-zch] ; Research Fund of State Key Laboratory for Marine Corrosion and Protection of Luoyang Ship Material Research Institute (LSMRI) ; State Key Laboratory for Marine Corrosion and Protection, Luoyang Ship Material Research Institute (LSMRI), China[KF190408] ; Key Research and Development Program of Shandong Province[2019GHY112085] ; Key Research and Development Program of Shandong Province[2019GHY112066] ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China|
|Table of Contents|
|冯昌. 多相异质结体系增强过渡金属Ⅵ 族化合物的光致阴极保护及光催化机制研究[D]. 中国科学院海洋研究所. 中国科学院大学,2021.|
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