本文關(guān)鍵詞： 氧還原反應(yīng) 電催化劑 碳納米管 聚苯胺 三聚氰胺　出處：《重慶大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：化石能源的消耗及其導(dǎo)致的污染問題,使得探索新的能源成為世界各國所面臨的重要挑戰(zhàn)。燃料電池因具有能量轉(zhuǎn)換效率高、污染低等優(yōu)勢而備受青睞。作為燃料電池重要組成部分的空氣電極,控制和影響電池性能高低的關(guān)鍵瓶頸,特別是空氣電池中的ORR具有動力學(xué)遲緩及反應(yīng)途徑多樣性的特點,導(dǎo)致電池很難大電流放電。尋找廉價易得高效的燃料電池陰極電催化劑來替代貴金屬鉑基催化劑是燃料電池發(fā)展的重要方向。本文選用廉價易得且高氮含量的聚苯胺、三聚氰胺來共同修飾碳納米管制備TM-N/C型催化劑。同時優(yōu)化催化劑的制備條件如熱處理時間、熱處理溫度以及金屬添加量等因素。實驗利用線性伏安掃描對其電化學(xué)活性進行測試,采用旋轉(zhuǎn)圓盤電極測試其催化機理及穩(wěn)定性,根據(jù)時間-電流曲線測試其耐甲醇性能,用SEM、XRD、XPS對催化劑的形貌及結(jié)構(gòu)進行表征測試。實驗結(jié)果表明,雙氮源共同修改碳納米管比單一氮源修飾具有明顯的優(yōu)勢,雙氮源參雜碳納米管在最優(yōu)條件下所制備的N/C催化劑起始氧還原電位可以到-35 m V,峰電位可以達到-113 m V;過渡金屬鈷的添加能夠提高催化劑的活性,Co-N/C-A與N/C相比其起始電位和峰電位分別正移5 m V和25 m V,且具有優(yōu)異的耐甲醇性能;Co-N/C-A催化劑在經(jīng)過AAT測試之后催化活性數(shù)據(jù)Eonset和Ehw分別僅降低了約23m V和10m V,在-0.4 V電位下的極限擴散電流密度jd也只降低了約0.4%,而商業(yè)Pt/C催化劑相應(yīng)的ORR電催化活性數(shù)據(jù)Eonset和Ehw卻分別降低了約68m V和20m V,在-0.4 V電位下的極限擴散電流密度jd降低了約4.6%,說明Co-N/C-A具有良好的穩(wěn)定長期穩(wěn)定性。重要的是,過渡金屬鈷的添加能夠改善催化劑的催化劑的機理使其按照四電子途徑進行還原,N/C催化劑的在催化氧還原反應(yīng)的過程的電子轉(zhuǎn)移數(shù)目為2.7,而CoN/C-A催化劑的為4.1。要使所制備催化劑的活性達到最佳,金屬添加量、熱處理時間和溫度都要控制在一定的值,最有條件為鈷添加量為20%時800℃下熱處理2h。
[Abstract]:The consumption of fossil energy and the pollution caused by it make the exploration of new energy become an important challenge for all countries in the world. Fuel cells have high energy conversion efficiency. Air electrode, which is an important part of fuel cell, is the key bottleneck to control and influence the performance of fuel cell. Especially, ORR in air battery is characterized by slow kinetics and diversity of reaction pathway. It is an important direction of development of fuel cells to find cheap and efficient cathodic electrocatalysts to replace precious metal platinum-based catalysts. In this paper, Polyaniline with low cost and high nitrogen content is used. Melamine is used to modify carbon nanotubes to prepare TM-N/C catalysts. At the same time, the preparation conditions such as heat treatment time are optimized. The electrochemical activity was tested by linear voltammetry, the catalytic mechanism and stability were tested by rotating disk electrode, and the methanol resistance was measured according to the time-current curve. The morphology and structure of the catalyst were characterized by SEMS-XRDX XPS. The experimental results showed that the modification of carbon nanotubes by diazo source had obvious advantages over that modified by single nitrogen source. The initial oxygen reduction potential and peak potential of N / C catalyst can reach -35 MV and -113 MV respectively, and the addition of cobalt in transition metal can improve the activity of the catalyst. The initial potential and peak potential shifted positively at 5 MV and 25 MV, respectively, and the Co-N / C-A catalyst exhibited excellent methanol resistance. After AAT test, the catalytic activity data of Eonset and Ehw decreased only about 23mV and 10mV, respectively. At the potential of -0.4 V, the catalytic activity data of Co-N / C-A catalyst decreased only about 23mV and 10mV, respectively. The limit diffusion current density (JD) also decreased by about 0.4g, while the corresponding ORR electrocatalytic activity data (Eonset and Ehw) of commercial Pt/C catalysts decreased by 68mV and 20mV, respectively, and the limiting diffusion current densities (JD) at -0.4 V potential decreased by about 4.6g / d, respectively. It shows that Co-N/C-A has good stability and long-term stability. The addition of cobalt in transition metal can improve the mechanism of catalyst so that the number of electron transfer in the process of catalytic oxygen reduction of N / C catalyst is 2.7, and that of CoN/C-A catalyst is 4.1. The activity of the catalyst was optimized. The amount of metal added, the time of heat treatment and the temperature should be controlled at a certain value. The most suitable condition is that the amount of cobalt added is 20 鈩，

本文編號：1500712