CAS OpenIR
负载型贵金属基复合纳米材料及其光电催化应用
唐嘉仪
Subtype硕士
Thesis Advisor杨军
2018-07
Degree Grantor中国科学院研究生院
Degree Name硕士
Degree Discipline材料工程
Keyword贵金属-半导体复合纳米材料,湿法化学,电子耦合效应,电催化甲醇氧化应,光催化分解水制氢
Abstract

贵金属基复合纳米材料,是通过将贵金属与其它不同类别的组分集成在一起,使得材料具有独特的物理化学特性,致使其在许多领域中都具有潜在的应用价值。其中,贵金属与半导体形成的复合纳米材料在光电催化领域表现出良好的催化性能,因此,其合成与应用已经引起研究者们广泛的关注,并取得了很多重要的成果。尽管如此,目前贵金属-半导体复合纳米材料合成中仍然存在一些难题,如水相合成受到低浓度限制,有机相合成中产生的颗粒尺寸则较大。因此,发展更为简单高效的合成方式,并对材料形貌、尺寸和组成进行调控,充分利用复合体系组分间的耦合效应来提升其催化性能,仍然是该领域研究的关键。本论文以此为思路进行研究,取得的成果如下:(1)发展了一种在有机相中负载制备Ag2S-Pt纳米复合物(Ag2S-PtNCs/C)的方法。首先,将Ag+前驱体负载于活性炭载体上,紧接着,向反应体系中加入预先分散于甲苯中的硫,在载体的抑制作用下,反应得到尺寸约4 nm的碳载Ag2S半导体纳米颗粒。然后,通过简单的液相还原法,向Ag2S纳米颗粒表面沉积贵金属铂(Pt),成功制备得到碳基上均匀分散的尺寸小于5 nm的负载型核壳结构Ag2S-PtNCs/C复合纳米颗粒。由于Ag2S-PtNCs/C中Ag2S与Pt的电子耦合效应,Ag2S-PtNCs/C在催化甲醇氧化反应(MOR)中表现出比商业Pt/C催化剂更好的面积活性和催化稳定性。(2)成功地将上述的制备方式进行拓展,合成出二元负载型CdS-PtNCs/C、PbS-PtNCs/C复合纳米颗粒以及三元负载型Au-Ag2S-PtNCs/C复合纳米颗粒。在电化学测试中,分析了不同硫化物半导体对Pt电催化MOR性能的影响。另外,Au组分的存在致使三元复合体系中的电子耦合效应增强,致使负载型三元复合纳米颗粒Au-Ag2S-PtNCs/C在MOR中表现出最好的催化活性和稳定性。(3)为提升氧化物半导体TiO2纳米颗粒光催化分解水制氢的效率,采用有机相中前驱体Au3+、Pt4+和Pd2+离子与TiO2-Ag中Ag纳米颗粒的伽伐尼置换反应(GRR), 制备得到了双金属TiO2-Ag/M (M = Au, Pd, Pt)合金纳米颗粒。该方法有效地控制双金属合金纳米颗粒的形貌、尺寸以及金属与半导体间的复合界面,也实现了对TiO2半导体表面贵金属组成的调控。由于Au的引入,TiO2-Ag/Au表现出比TiO2-Ag增强的等离子体共振吸收特性,其光催化分解水制氢的效率也提升了约3.3倍。Pt和Pd引入后,致使复合界面形成肖特基势垒,增强了半导体的光生电子-空穴对的分离效果,有效地提升了TiO2的光催化产氢效率。;Noble metal-based nanocomposites that integrate different domains to form heterogeneous structure usually exhibit enhanced physical/chemical properties, resulting in their promising applications in many fields. Specially, the nanocomposites consisting of noble metals and semiconductor have showed superior catalytic peoperties in photoelectrocatalysis. Therefore, their synthesis and application have attracted a great attention, and many important achievements have been obtained. However, the synthesis still was seriously restricted by some obstacles, such as the limitation of the low concentration for their synthesis in water phase and the large particle size in organic phase. Hence, it still is quite a challenge to develope the simple and efficient way for the synthesis of nanocomposites consisting of noble metals and semiconductora as well as the engineering of their morphology, structure and composition that would better utilize the electronic effect between them for the improvement of their catalytic properties. Based on the research idea, the detailed achievements in this thesis are listed as following:(1) A facile and efficient way for the synthesis of Ag2S-PtNCs/C has been developed. Specifically, the Ag+ precursor was firstly loaded on active carbon substrate. Subsequently, adding sulfur powder dispersed in tolune to the above system, the Ag2S nanoparticles with the mean size of about 4 nm were gained in inhibiting effect of support. Then, Pt was desposited on the surface of Ag2S nanoparticles via the simple liquid phase reducing method, and the Ag2S-PtNCs/C nanocomposites with the average of about 5 nm were ultimately obtained. Compared with those of commercial Pt/C catalyst, Ag2S-PtNCs/C nanocomposites show better specific activity and durability for the electrocatalytic oxidation of methanol due to the existed electronic effect between Pt and Ag2S.(2) The above strategy was extended, and binary supported CdS-PtNCs/C and PbS-PtNCs/C nanocomposites and ternary supported Au-Ag2S-PtNCs/C nanocomposites were successfully gained. In the electrocatalytic measurement, the effluence of different sulfide semiconductors on the catalytic properties for MOR was analyzed. In addition, Au-Ag2S-PtNCs/C exhibited the highest electrocatalytic activity and stability in comparison with those of other binary and ternary nanocomposits, which should be attributed to the enhanced electronic effect aroused by Au.(3) For the enhanced efficiency of oxide semiconductor TiO2 of photocatalytic water-splitting for hydrogen, bimetallic TiO2-Ag/M (M = Au, Pd, Pt) alloy nanocomposites were synthesized via GRR between Au3+, Pd2+ and Pt4+ ions precursors and Ag nanoparticles located the surface of TiO2, which efficiently controlled the morphology and size of bimetallic nanoparticles, and successfully tuned the compound interface between noble metal and semiconductor TiO2 and compositon of noble metal on the surface of TiO2. Because of the existence of Au, TiO2-Ag/Au not only showed stronger plasma resonance absorption, but also exhibited 3.3 times higher efficiency of photocatalytic water-splitting for hydrogen, compared with those of TiO2-Ag nanocomposites. In addition, alloying Ag on the surface of TiO2 with Pd and Pt, the schottky barrier was formed in the compound interface between TiO2 and noble metal, which enhanced the dissociation of photogenerated electron hole pair in TiO2, thus resulting in the improvements of their efficiency of the photocatalytic water-splitting for hydrogen. 

Language中文
Document Type学位论文
Identifierhttp://ir.ipe.ac.cn/handle/122111/26859
Collection中国科学院过程工程研究所
研究所(批量导入)
Recommended Citation
GB/T 7714
唐嘉仪. 负载型贵金属基复合纳米材料及其光电催化应用[D]. 中国科学院研究生院,2018.
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