本文關鍵詞：鉑族貴金屬納米材料的制備及其催化性能研究　出處：《山東大學》2015年博士論文　論文類型：學位論文

  更多相關文章： 納米材料 鉑族 貴金屬 雜化 催化 電催化 能源轉(zhuǎn)化 形貌調(diào)控

【摘要】：鉑族貴金屬納米材料由于在異相催化、電化學等方面的獨特性能而日益受到人們的重視。納米材料的催化活性通常與納米結(jié)構(gòu)所暴露的晶面、組成和結(jié)構(gòu)有著密切的關系。金屬雜化納米材料不僅能有效改變單一成分的電子結(jié)構(gòu),不同組分之間存在的協(xié)同效應,更能顯著改變材料的宏觀性質(zhì),提高催化劑的催化活性。同時,貴金屬與過渡金屬之間形成的雜化材料還能降低鉑族金屬的使用量,這對于地球上儲量并不豐富的鉑族元素來說,無疑能夠顯著降低催化劑用量和成本。鉑族雜化納米材料由于成分較多,催化劑的制備過程復雜,結(jié)構(gòu)控制相當?shù)睦щy,這對于催化劑的制備提出了很大的挑戰(zhàn)。因此,設計和發(fā)展簡單、有效的制備方法來制備鉑族貴金屬的雜化材料,對于促進鉑族貴金屬在催化等方面的廣泛應用是非常必要的。本論文中,設法合成了一系列的Pt、Pd、Rh雜化納米材料,研究了其形成機制,并探索了它們在液相催化,電催化等方面的應用。主要研究結(jié)果如下：1.通過動力學調(diào)控方法制備了Au納米棒-RhAg雜化納米材料,分別得到了啞鈴狀結(jié)構(gòu)、毛刷狀結(jié)構(gòu)和棒狀Au@Ag-Rh納米搖鈴結(jié)構(gòu)。通過對反應機制的研究發(fā)現(xiàn),隨著Rh3+和Ag還原速率的增加,RhAg在Au納米棒上的沉積方式是逐漸由兩端沉積向全身沉積轉(zhuǎn)變,進一步的增加還原速率,Ag首先在Au納米棒表面形成殼層,隨后Rh+與Ag殼層發(fā)生置換反應得到了納米搖鈴結(jié)構(gòu)。以OPDA偶聯(lián)反應為模型研究了這三種結(jié)構(gòu)的催化效率,毛刷狀結(jié)構(gòu)啞鈴型結(jié)構(gòu)納米搖鈴結(jié)構(gòu),催化效率的差異主要和Rh暴露的活性面積有關。2.通過簡單的水熱方法成功制備了Pd-Rh雙金屬核-框架結(jié)構(gòu)和核-殼結(jié)構(gòu),通過選擇性的化學腐蝕,成功的得到了Pd-Rh雙金屬納米框架結(jié)構(gòu)和納米盒子。通過一系列的對照實驗以及詳細的結(jié)構(gòu)表征,研究了Pd-Rh核-框架結(jié)構(gòu)和核-殼結(jié)構(gòu)的形成過程和反應機制,揭示了Rh3+的存在抑制了Pd孿晶晶種的形成,使得Pd生成了更穩(wěn)定的單晶立方塊。利用OPDA偶聯(lián)反應為模型評價了所得到的Pd-Rh四種不同結(jié)構(gòu)的催化性能,催化效率如下：Pd-Rh納米盒子Pd-Rh納米框架Pd-Rh核-框架Pd-Rh核-殼結(jié)構(gòu)。催化性能的差異主要和空心結(jié)構(gòu)以及Rh含量有密切的關系。3.發(fā)展了簡單的一鍋法制備了三金屬Au-Ag@Rh-Ag納米搖鈴結(jié)構(gòu)和雙金屬Rh-Ag空心球結(jié)構(gòu)。通過時間演化分析對其形成過程進行了詳細研究,揭示了其形成納米搖鈴結(jié)構(gòu)和空心結(jié)構(gòu)的實質(zhì)分別是首先形成了Au-Ag核-殼結(jié)構(gòu)和Ag納米球,隨后Ag殼層與Rh3+發(fā)生置換反應形成上述空心結(jié)構(gòu)。OPDA的催化偶聯(lián)反應結(jié)果表明,Au-Ag@Rh-Ag納米搖鈴結(jié)構(gòu)的催化活性要優(yōu)于雙金屬Rh-Ag空心球結(jié)構(gòu),催化性能的差異可能源于Rh活性面積的差異。4.第一次實現(xiàn)了五重孿晶Pd納米線到三組分PtPdCu內(nèi)凹立方塊的轉(zhuǎn)變。通過對反應機制的詳細研究發(fā)現(xiàn),五重孿晶Pd納米線到PtPdCu內(nèi)凹立方塊的轉(zhuǎn)變經(jīng)過了兩步：孿晶Pd納米線的腐蝕和Pt4+、Pd2+、Cu2+共還原,之所以孿晶Pd納米線被腐蝕主要是因為孿晶的晶格應力所導致的晶體穩(wěn)定性降低。電催化氧化甲酸表明,內(nèi)凹的PtPdCu立方塊相對于商業(yè)Pt/C催化劑具有更高的催化活性和更好的穩(wěn)定性,催化活性的提高主要是因為內(nèi)凹結(jié)構(gòu)的存在提供了大量的臺階原子,同時雜原子的存在使得甲酸催化氧化更多的經(jīng)過直接氧化路徑,催化劑的穩(wěn)定性得到提高。
[Abstract]:Platinum noble metal nano materials because of differences in the catalytic performance, unique electrochemistry increasingly attention. The catalytic activity of nano materials and nano structure usually exposed surface, composition and structure are closely related. The electronic structure of metal nano hybrid material not only can effectively change the single component, synergy the effect between different components can significantly change the macroscopic properties of materials, improve the catalytic activity of the catalyst. At the same time, the hybrid materials can also be formed between the noble metal and transition metal, reduce the amount of platinum metals, the earth is not rich in reserves of platinum group elements, it can significantly reduce the amount of catalyst and the cost of platinum. Hybrid nano materials because of the many components, preparation process of the catalyst complex structure, difficult to control, the preparation of the catalyst is a great The challenge. Therefore, the design and development of a simple and effective method for the preparation of hybrid materials for preparing platinum group metals, it is necessary to promote wide application of platinum group metals in catalytic fields. In this thesis, to a series of Pt, the synthesis of Pd, Rh hybrid nano materials. The formation mechanism of the research, and to explore their application in liquid phase catalysis, electrocatalysis and so on. The main results are as follows: 1. by dynamic regulation method to prepare Au nanorod -RhAg hybrid materials were obtained dumbbell shaped brush like structure and rod like Au@Ag-Rh nano structure. Through the research on the reaction bell the mechanism of Rh3+ and Ag, with the reduction rate of the increase of deposition in Au nanorods on RhAg is changing gradually from both ends to the body of sedimentary deposition, further increase the reduction rate of Ag, first formed shell on Au nanorods, then Rh+ and Ag shell replacement reaction of nano structures have been studied. A catalytic efficiency of the three kinds of OPDA coupling reaction was used as a model, a brush like structure of dumbbell shaped structure of nano structure between the catalytic efficiency of the bell, and the main active area exposed to Rh about.2. was successfully through a simple hydrothermal method Pd-Rh double metal core frame structure and core-shell structure were prepared by chemical etching selectivity, successfully obtained Pd-Rh double metal nano structure and nano box. Through a series of control experiments and detailed structural characterization, formation process and reaction mechanism of Pd-Rh nuclear structure and core-shell structure has been studied and revealed the presence of Rh3+ Pd inhibited the formation of twin crystal, making the Pd more stable single crystal cubic block is generated. The evaluation of Pd-Rh obtained by four different structures of catalytic coupling reaction using OPDA model Can, the catalytic efficiency is as follows: Pd-Rh nano Pd-Rh nano Pd-Rh frame box core framework Pd-Rh core-shell structure. The main difference of catalytic performance and hollow structure and the content of Rh.3. is closely related to the development of a simple one pot method three metal Au-Ag@Rh-Ag nano structure and preparation of double gold ring is Rh-Ag hollow spherical structure. By the time evolution analysis of the forming process were studied in detail, reveals the essence of the formation of nano structure and bell hollow structure are first formed core-shell structure Au-Ag and Ag nanoparticles, the catalytic coupling reaction of Ag and Rh3+ and shell replacement reaction to form the hollow structure of.OPDA showed that the photocatalytic activity of Au-Ag@Rh-Ag nano ring structure superior to the bimetallic Rh-Ag hollow spheres, differences in the catalytic performance could be attributed to the differences in the active area of Rh.4. for the first time to achieve a five fold twinned Pd nanowires to three Component change PtPdCu concave cube. Through detailed study of the reaction mechanism, change five fold twinned Pd nanowires to PtPdCu concave cubes through two steps: corrosion and Pt4+, twinned Pd nanowires Pd2+, Cu2+ coreduction, the twin Pd nanowires were mainly because of reduced corrosion the stability of crystal lattice stress caused by twinning. Showed that the electrocatalytic oxidation of formic acid, a concave PtPdCu cube with respect to the stability of commercial Pt/C catalyst has higher catalytic activity and better catalytic activity, the increase is mainly because the concave structure provides a step in a lot of atoms, and atoms in the presence of through direct oxidation of formic acid catalytic oxidation route more, the stability of the catalyst is improved.

【學位授予單位】：山東大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TB383.1

【參考文獻】

相關期刊論文 前1條

1 熊婷;林劍云;商中瑾;張賢土;林旋;田偉;鐘起玲;任斌;;以Ag為模板制備Pt納米空球及其對甲醇氧化的電催化性能[J];高等學�；瘜W學報;2014年11期

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本文編號：1420902