發(fā)布時(shí)間：2018-04-08 15:42

  本文選題：碳納米管　切入點(diǎn)：氮摻雜　出處：《新疆大學(xué)》2017年碩士論文

【摘要】：質(zhì)子交換膜燃料電池(PEMFCs)之所以可以成為一種節(jié)能環(huán)保、高效的能源裝置,主要是因其不受卡諾循環(huán)限制、轉(zhuǎn)化效率高、操作溫度區(qū)間大、比功率和比能量高、污染小、噪聲小、原料廣、用途多、安全可靠等優(yōu)點(diǎn),且在電動(dòng)車、航天、潛艇、等眾多領(lǐng)域都具有應(yīng)用前景。制備出高活性的催化劑對于提升PEMFCs的性能有著非常重要的作用。目前,Pt/C因其較高的活性成為PEMFCs的商用催化劑,但是仍然有很多的問題存在。例如在長時(shí)間的運(yùn)行過程中,Pt催化劑成本較高、碳載體會(huì)對催化劑進(jìn)行腐蝕、Pt原子發(fā)生溶解、穩(wěn)定性差及與燃料產(chǎn)生混合電位發(fā)生中毒等現(xiàn)象,造成催化劑的活性大幅度降低,這些因素都會(huì)制約PEMFCs的商業(yè)化發(fā)展。因此,價(jià)格低廉、環(huán)境友好、具有高電催化活性的氧還原催化劑的研發(fā)成為提高PEMFCs性能的關(guān)鍵。本文以簡便的方法合成了三種高效的陰極電催化劑,并對其形貌特征和電化學(xué)性能進(jìn)行了相應(yīng)的測試。主要研究結(jié)果如下:(1)以氯化鐵為鐵源,三聚氰胺為氮源,氧化石墨烯為載體,采用高溫煅燒法制得了三明治夾層結(jié)構(gòu)的Fe3C@NGs復(fù)合催化劑,XRD、Raman、SEM、TEM等一系列物理測試結(jié)果顯示:Fe3C納米原子均勻分散在褶皺的氮摻雜氧化石墨烯(NGs)薄層上。并考察了氧化石墨烯(GO)負(fù)載量對制得的催化劑在堿性介質(zhì)中的氧還原活性(ORR)的影響。實(shí)驗(yàn)結(jié)果表明:當(dāng)GO負(fù)載量為80 mg時(shí),所制得的催化劑具有最高的氧還原活性,同時(shí)表現(xiàn)出較優(yōu)的抗甲醇性能和較好的循環(huán)穩(wěn)定性,該催化劑優(yōu)異的性能歸因于較高的含氮量,較豐富的Fe-Nx/C-Nx活性位點(diǎn)、較大的比表面積和較豐富的孔結(jié)構(gòu)。(2)以聚乙烯吡咯烷酮(PVP)為分散劑,采用高溫煅燒法原位合成了雙功能空心鏈條狀的FN-B-800復(fù)合材料,并對煅燒溫度和前驅(qū)體濃度等因素進(jìn)行了一系列的考察。實(shí)驗(yàn)結(jié)果表明:氯化鐵濃度為4 mmol,煅燒溫度為800°C,所制得的復(fù)合催化劑表現(xiàn)出更高的ORR活性和吸氧(OER)活性,良好的甲醇容納性能及優(yōu)異的循環(huán)穩(wěn)定性。經(jīng)分析認(rèn)為,PVP的使用可將Fe3C納米粒子均勻分布在空心鏈條狀的氮摻雜碳納米管(n CNTs)當(dāng)中,從而有效地阻止Fe3C的聚集或堆積,同時(shí)有利于保持活性物質(zhì)較大的比表面積。(3)以葡萄糖為碳源,尿素為氮源,氯化鐵為鐵源,采用高溫煅燒法制得蜂窩狀Fe3C@NGC催化劑。經(jīng)XRD,SEM和TEM表征可知,Fe3C納米晶體均勻分布在氮摻雜石墨化碳上。利用電化學(xué)工作站對所制得的復(fù)合材料的電化學(xué)性能進(jìn)行了測試,通過與Fe3C@GC和NGC相比較,發(fā)現(xiàn)Fe3C@NGC催化劑表現(xiàn)出更優(yōu)的電催化活性、良好的循環(huán)穩(wěn)定性及較優(yōu)的甲醇容納性。Fe3C@NGC催化劑所表現(xiàn)出的良好性能主要是由于復(fù)合材料提供更大的比表面積、更多的反應(yīng)活性位點(diǎn)和更通暢的離子傳輸通道。
[Abstract]:The proton exchange membrane fuel cell (PEMFCs) can be a kind of energy saving, environmental protection and high efficiency energy device, mainly because it is not restricted by the Carnot cycle, has high conversion efficiency, has a large operating temperature range, has high specific power and specific energy, has less pollution, and has less noise.It has many advantages, such as wide raw materials, many uses, safety and reliability, and has the prospect of application in many fields such as electric vehicle, aerospace, submarine and so on.The preparation of highly active catalysts plays an important role in improving the performance of PEMFCs.At present, Pt- / C has become a commercial catalyst for PEMFCs because of its high activity, but there are still many problems.For example, the cost of Pt catalyst is high during a long period of operation, the carbon carrier will corrode the Pt atom, the stability will be poor and the mixed potential with fuel will be poisoned, the activity of the catalyst will be greatly reduced.These factors will restrict the commercial development of PEMFCs.Therefore, the research and development of oxygen reduction catalyst with low cost, environment friendly and high electrocatalytic activity has become the key to improve the performance of PEMFCs.In this paper, three kinds of high efficient cathodic electrocatalysts were synthesized by a simple method, and their morphologies and electrochemical properties were tested.The main results are as follows: (1) using ferric chloride as Tie Yuan, melamine as nitrogen source and graphene oxide as carrier,A series of physical measurements such as Fe3C@NGs composite catalyst with sandwich sandwich structure (Fe3C@NGs) and SEMT-TEM show that the nano-atoms of Fe3C are uniformly dispersed on the thin layer of ruffled nitrogen-doped graphene oxide (NGS).The effect of the loading amount of graphene oxide on the oxygen reduction activity of the prepared catalyst in alkaline medium was also investigated.The experimental results showed that the catalyst with 80 mg go loading had the highest oxygen reduction activity, and showed better methanol resistance and cycle stability. The excellent performance of the catalyst was attributed to the higher nitrogen content.Bifunctional hollow chain FN-B-800 composites were synthesized by high temperature calcination with polyvinylpyrrolidone (PVP) as dispersant, with rich specific surface area and rich pore structure.A series of factors such as calcination temperature and precursor concentration were investigated.The experimental results show that the composite catalyst has higher ORR activity and higher oxygen absorbent activity, better methanol holding capacity and better cycling stability than the composite catalyst with 4 mmol / L ferric chloride concentration and 800 擄C calcination temperature.It is considered that the Fe3C nanoparticles can be uniformly distributed in the hollow chain-like nitrogen-doped carbon nanotubes (CNTs), thus effectively preventing the aggregation or accumulation of Fe3C.At the same time, the honeycomb Fe3C@NGC catalyst was prepared by high temperature calcination with glucose as carbon source, urea as nitrogen source and ferric chloride as Tie Yuan.The results of SEM and TEM show that Fe _ 3C nanocrystals are uniformly distributed on nitrogen-doped graphitized carbon.The electrochemical properties of the composites were tested by electrochemical workstation. Compared with Fe3C@GC and NGC, the electrocatalytic activity of Fe3C@NGC catalyst was found to be better.The good cycling stability and the excellent methanol accommodability. Fe3C@ NGC catalyst showed good performance mainly because the composite provided larger specific surface area more reactive sites and more unobstructed ion transport channels.
【學(xué)位授予單位】：新疆大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O643.36;TM911.4

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本文編號：1722255