本文選題：直接甲醇燃料電池 + PtRu合金�。� 參考：《太原理工大學》2017年碩士論文

【摘要】：直接甲醇燃料電池(DMFC)因能量轉(zhuǎn)換效率與比能量較高,甲醇來源豐富,潔凈環(huán)保,可低溫快速啟動的優(yōu)勢,使其可成為未來便攜式產(chǎn)品應用的主流。目前DMFC的能量轉(zhuǎn)換效率和功率密度與理論值存在差異,究其根本,是因為催化劑活性和穩(wěn)定性達不到理想要求。明確催化機理對催化劑的發(fā)展至關重要。催化機理的研究可為提高催化劑性能,改進催化劑制備方法提供理論依據(jù)。PtRu合金是目前公認穩(wěn)定性、電化學活性最好的合金催化劑之一,但其電催化甲醇氧化的機理一直存在爭議,阻礙了催化劑研究的進一步發(fā)展。目前研究者們主張雙功能機理或主張電子效應機理,雖然這兩種機理從不同的角度出發(fā),能夠闡明Pt基納米合金的一些實驗現(xiàn)象,各有一定的說服力,但也都存在不能說明的問題。因此本論文對PtRu合金催化劑電催化氧化甲醇催化機理做了進一步探索,并提出PtRu合金催化劑電催化氧化甲醇是電子效應與雙功能機理協(xié)同作用,對Pt基納米金屬新型催化劑的研發(fā)提供新的依據(jù)。本文采用液相還原法和兩步化學還原法分別制備了直徑相近、Pt/Ru原子比例不同的合金型PtRu/C和核殼型Ru@Pt/C催化劑,通過XRD、TEM、EDS、XPS等物理技術手段,對催化劑的晶體結構、表面元素組成進行了物理表征,說明兩種催化劑中Pt、Ru原子間的電子效應的存在及其強度。通過CV、EIS、CA等測試手段對催化劑的電化學性能進行了表征。對比分析表征結果,進一步探究了合金型PtRu/C催化劑電催化氧化甲醇的催化作用機理。TEM表征,EDS,XPS實測催化劑Pt/Ru原子比以及0.5 mol/L硫酸溶液中的循環(huán)伏安曲線共同說明,制備的兩類催化劑均為球形,粒徑約9~11nm,Ru@Pt/C催化劑為核殼結構,Pt Ru/C催化劑為合金結構。XRD結果顯示,Pt0.33Ru1/C中Pt原子呈非晶態(tài)結構,Pt0.5Ru1/C中Pt原子存在非晶態(tài)結構趨勢,Ru1@Pt0.33/C中Pt原子形成微晶薄膜。通過分析XRD和XPS的結果推斷出兩種催化劑均存在電子效應。Pt原子呈晶態(tài)結構時,隨Pt原子比增大,兩種催化劑電子效應強度均減小,其中Pt1Ru1/C,Ru1@Pt0.5/C在各自體系中電子效應強度最高,相同Pt/Ru原子比下,兩種催化劑電子效應近似相同。循環(huán)伏安、交流阻抗、計時電流測試結果說明,當Pt原子呈晶態(tài)結構時,隨Pt原子比增大,兩種催化劑催化活性均減小,Pt1Ru1/C,Ru1@Pt0.5/C催化劑在各自催化體系中性能最佳,這與電子效應強度隨Pt原子比增大而減小的變化規(guī)律相一致。當Pt原子呈非晶態(tài)或微晶結構時,兩種催化劑催化性能減弱。PtRu/C催化劑催化甲醇氧化反應級數(shù)大于Ru@Pt/C催化劑,證明兩種催化劑催化機理不同。相同Pt/Ru原子比下,PtRu/C催化劑催化性能遠優(yōu)于Ru@Pt/C催化劑,兩者電子效應近似相同,證明PtRu/C催化劑存在Pt、Ru活性位的“雙功能活性中心”促進作用。綜合以上實驗結果本論文得出以下觀點:PtRu合金催化劑電催化氧化甲醇是電子效應與雙功能機理協(xié)同作用。
[Abstract]:Direct methanol fuel cell (DMFC) has the advantages of high energy conversion efficiency and specific energy, abundant methanol source, clean and environmental protection, and can be started quickly at low temperature, which makes it become the mainstream of portable products in the future.At present, the energy conversion efficiency and power density of DMFC are different from the theoretical values. The fundamental reason is that the activity and stability of the catalyst can not meet the ideal requirements.It is very important to clarify the catalytic mechanism for the development of catalysts.The study of catalytic mechanism can provide theoretical basis for improving the performance of catalyst and improving the preparation method of catalyst. PtRu alloy is recognized as one of the most stable alloy catalysts with the best electrochemical activity.However, the electrocatalytic mechanism of methanol oxidation has been controversial, which hinders the further development of catalyst research.At present, researchers advocate the bifunctional mechanism or the electronic effect mechanism, although the two mechanisms can elucidate some experimental phenomena of Pt-base nanocrystalline alloys from different angles, and each of them is persuasive.But there are also problems that cannot be explained.In this paper, the electrocatalytic oxidation mechanism of methanol over PtRu alloy catalyst is further explored, and it is suggested that the electrocatalytic oxidation of methanol over PtRu alloy catalyst is a synergistic effect of electron effect and bifunctional mechanism.It provides a new basis for the research and development of Pt-based nano-metal catalysts.In this paper, alloy type PtRu/C and core-shell type PtRu/C catalysts with similar diameter of Pt / Ru atom ratio were prepared by liquid phase reduction method and two-step chemical reduction method. The crystal structure of the catalyst was studied by means of physical techniques such as XRDX Tem Tem EDS.The physical characterization of the composition of the surface elements indicates the existence and intensity of the electron effect between the two kinds of catalysts.The electrochemical properties of the catalyst were characterized by means of CVN EIS-CA and so on.The mechanism of electrocatalytic oxidation of methanol over alloyed PtRu/C catalyst was studied. Tem characterization showed that the atomic ratio of Pt/Ru and cyclic voltammetry in 0.5 mol/L sulfuric acid solution were measured by EDSXPS.By analyzing the results of XRD and XPS, it is inferred that the electron effect intensity decreases with the increase of Pt atom ratio when both catalysts have electron effect. The electron effect intensity of Pt1Ru1Ru1 / CnRu@ Pt0.5% C is the highest in their respective systems.At the same Pt/Ru atomic ratio, the electron effects of the two catalysts are approximately the same.This is consistent with the law that the electron effect intensity decreases with the increase of Pt atomic ratio.When Pt atoms were amorphous or microcrystalline, the catalytic performance of the two catalysts was weakened. The catalytic order of methanol oxidation over PtRu- / C catalyst was higher than that of Ru@Pt/C catalyst, which proved that the catalytic mechanism of the two catalysts was different.At the same Pt/Ru atom ratio, the catalytic performance of PtRu-C catalyst is much better than that of Ru@Pt/C catalyst, and the electron effect of both catalysts is approximately the same. It is proved that there exists a "bifunctional active center" in the catalytic activity of PTR Ru in PtRu/C catalyst.Based on the above experimental results, the following points are obtained: the electrocatalytic oxidation of methanol over the 1: PtRu alloy catalyst is a synergistic effect of electron effect and bifunctional mechanism.
【學位授予單位】：太原理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O643.36;TM911.4

【參考文獻】

相關期刊論文 前10條

1 趙碩;段東紅;衛(wèi)國強;張忠林;郝曉剛;劉世斌;;核殼型Ru@Pt在甲醇電催化氧化反應中的電子效應研究[J];太原理工大學學報;2016年04期

2 劉世斌;馬艷華;衛(wèi)國強;張忠林;郝曉剛;段東紅;;非晶態(tài)Pt殼層Ni@Pt納米粒子的甲醇電催化氧化動力學[J];太原理工大學學報;2012年03期

3 王銳;訾學紅;劉立成;戴洪興;何洪;;核殼結構雙金屬納米粒子的研究與應用[J];化學進展;2010年Z1期

4 蔡杭鋒;丁建波;;直接甲醇燃料電池用抗CO電催化劑研究進展[J];浙江工業(yè)大學學報;2007年03期

5 彭紅建;謝佑卿;聶躍莊;;電催化劑Pt的電子結構和催化性能[J];中南大學學報(自然科學版);2007年01期

6 李金峰;宋煥巧;邱新平;;直接甲醇燃料電池陽極催化劑的研究進展[J];電源技術;2007年02期

7 陳煜;唐亞文;李鋼;劉長鵬;高穎;邢巍;陸天虹;;一種制備碳載高合金化Pt-Ru催化劑的方法[J];無機化學學報;2006年01期

8 李蘭蘭,魏子棟,李莉;DMFC中甲醇氧化催化劑的催化機理[J];電源技術;2004年05期

9 汪國雄,孫公權,辛勤,衣寶廉;直接甲醇燃料電池[J];物理;2004年03期

10 侯中軍,俞紅梅,衣寶廉,林治銀,張華民;高活性的PtRu/C抗CO催化劑[J];電源技術;2002年04期

相關碩士學位論文 前1條

1 張婷;直接甲醇燃料電池PtRu催化劑表面CO中毒的理論研究[D];江西師范大學;2005年

，

本文編號：1732959