兰州大学机构库 >化学化工学院
Alternative TitleStudy on Photocatalytic Hydrogen Production of Polyoxometalates and ZnIn2S4 Composite Catalytic System
Thesis Advisor马宝春
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name工学硕士
Degree Discipline材料与化工
KeywordZnIn2S4 ZnIn2S4 多金属氧酸盐 polyoxometalates 太阳能 solar energy 光催化水分解 photocatalytic water decomposition 制氢 hydrogen production

随着世界范围内的能源短缺,以及各国对环境保护的日益重视,可再生能源越来越受到人们的关注并得到迅速发展。太阳能有着低碳低污染的特点,是一种十分具有发展前景的清洁可再生能源。光合作用是自然界最重要的物质来源和能量来源,是一个巨型的绿色化工厂。如何模拟光合作用将太阳能转化为化学能一直是科学界具有挑战性的课题,其中光催化水分解反应(2H2O→2H2 + O2)能将太阳能转化为化学能并且制得高热值和清洁的氢气,是一种具有发展前景的研究方向。多金属氧酸盐(Polyoxometalates),简称多酸,被认为是光催化水分解的潜在候选者,可以对半导体光催化剂进行改性并且提高光催化活性。在产氢光催化剂中,ZnIn2S4作为一种性能优异、稳定性良好、不含有毒金属离子的催化剂而被广泛研究。本论文围绕以ZnIn2S4为主体光催化剂,通过引入多金属氧酸盐作为助催化剂和引入元素掺杂等方法,研究了光催化水分解析氢的活性和稳定性,并探究了光催化机理,主要内容如下:

1. ZnIn2S4具有对可见光响应,易于调控等优点,但ZnIn2S4光生载流子分离效率低,捕光能力较弱等缺点制约了ZnIn2S4催化剂的光催化活性。本论文构建了含有硫缺陷的ZnIn2S4,通过EPR电子顺磁共振等手段证实了硫缺陷的存在。同时通过引入多酸助催化剂Na6K4[Ni4(H2O)2(PW9O34)2]·32H2O,通过构建催化体系加快了光生电子的转移,一方面降低了ZnIn2S4的光腐蚀,另一方面提升了光催化产氢速率。通过表面光电压谱等手段证实了光生电子从含有硫缺陷的ZnIn2S4向镍基多酸移动。同时通过循环伏安法测试得到了不同多酸的LUMO能级,揭示了与ZnIn2S4最匹配的多酸LUMO能级能够提高光生电子的传输速率,与光催化产氢实验结果一致,从而显著提高了光催化制氢性能。

2. 元素掺杂是促进ZnIn2S4高效光催化水分解的有效措施之一,一般来说,通过元素掺杂可以增大吸收光范围,加速光生电子和空穴分离,从而改善ZnIn2S4的催化活性。基于此,通过以Anderson型多酸(NH4)4[NiMo6O24H6]·5H2O作为双金属源,在水热法合成ZnIn2S4纳米片过程中来构建Ni和Mo双金属掺杂,表征结果证实Ni和Mo双金属成功掺杂入ZnIn2S4纳米片中。通过分析能带结构展示了双金属掺杂可以拓宽催化剂的光吸收范围,促进了催化剂的还原能力,同时通过光致发光光谱等表征证实了双金属掺杂可以抑制光生载流子的复合,提升光生载流子的分离效率,从而改善了光催化产氢性能。这项工作为设计高效的ZnIn2S4光催化制氢催化剂,提供了新的借鉴与思路。

Other Abstract

With the global energy shortage and the increasing emphasis on environmental protection in various countries, renewable energy is receiving increasing attention and developing rapidly. Solar energy is a promising clean renewable energy source with low carbon and low pollution characteristics.  Photosynthesis is the most important source of material and energy in nature, and it is a giant green chemical plant. How to simulate photosynthesis and convert solar energy into chemical energy has always been a challenging topic in the scientific community. Among them, photocatalytic water decomposition reaction (2H2O → 2H2+O2) can convert solar energy into chemical energy and produce high combustion value and clean hydrogen gas, which is a promising research direction. Polyoxometalates are considered potential candidates for photocatalytic water decomposition, which can modify semiconductor photocatalysts and enhance their photocatalytic activity. Among photocatalysts, ZnIn2S4 was widely studied as a catalyst with excellent performance, good stability, and no toxic metal ions. In this work, the activity and stability of photocatalytic water splitting of hydrogen was investigated, and the photocatalytic mechanism was explored around the use of ZnIn2S4 as the main photocatalyst, through the introduction of polyoxometalates as co-catalysts and the introduction of elemental doping, etc. The main content is as follows:

1. ZnIn2S4 has advantages such as visible light response and easy to modulate, but the low separation efficiency of photo generated carriers and weak light harvesting ability of ZnIn2S4 restrict its photocatalytic activity. Here, ZnIn2S4 with sulfur defects was constructed, and the existence of sulfur defects was confirmed through electron paramagnetic resonance and other means. Meanwhile, by introducing the polyoxometalates co-catalyst Na6K4[Ni4(H2O)2(PW9O34)2]·32H2O, the photogenerated electron transfer was accelerated through the construction of the catalytic system, which on the one hand reduced the photo corrosion of ZnIn2S4, and on the other hand enhanced the photocatalytic hydrogen production rate. The movement of photogenerated electrons from ZnIn2S4 containing sulfur defects to nickel-based polyoxometalates was confirmed by means of surface photovoltage spectroscopy. Meanwhile, the LUMO energy levels of different polyoxometalates were obtained by cyclic voltammetry, revealing that the LUMO energy level of the polyoxometalates that best matches ZnIn2S4 can enhance the photogenerated electron transport rate, which is consistent with the experimental results of the photocatalytic hydrogen production, and thus significantly improves the performance of photocatalytic hydrogen production.

2. Element doping is one of the effective measures to regulate the photocatalytic water decomposition of ZnIn2S4. As a general rule, element doping can increase the absorption range, accelerate the separation of photo generated electrons and holes, and thus improve the catalytic activity of ZnIn2S4. Based on this, Ni and Mo bimetallic doping was constructed during the hydrothermal synthesis of ZnIn2S4 nanosheets using Anderson type polyoxometalates (NH4)4[NiMo6O24H6]·5H2O as a bimetallic source. The characterization results confirmed that Ni and Mo bimetallic doping was successfully incorporated into ZnIn2S4 nanosheets. By analyzing the band structure, it was demonstrated that bimetallic doping can broaden the light absorption range of the catalyst, promote its reduction ability, improve the separation efficiency of photo generated charge carriers, and thus improve the photocatalytic hydrogen production performance. This work provides new references and ideas for designing efficient ZnIn2S4 photocatalytic hydrogen production catalysts.

MOST Discipline Catalogue工学 - 材料与化工
Other Code262010_220200922041
Document Type学位论文
Recommended Citation
GB/T 7714
尤可嘉. 多金属氧酸盐与ZnIn2S4复合催化体系的光催化产氢研究[D]. 兰州. 兰州大学,2023.
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