本文選題：質(zhì)子交換膜燃料電池 + 氧還原反應(yīng)　； 參考：《中國(guó)礦業(yè)大學(xué)》2017年碩士論文

【摘要】：在質(zhì)子交換膜燃料電池(PEMFCs)中,鉑是已知最佳的氧還原反應(yīng)(ORR)催化劑,但是其緩慢的氧還原動(dòng)力學(xué)、有限的存儲(chǔ)和高昂的價(jià)格嚴(yán)重阻礙了PEMFCs的商業(yè)化。因此,低鉑甚至是非鉑ORR催化劑被廣泛研究。最近研究表明,核殼結(jié)構(gòu)不但降低了催化劑的鉑載量,而且提高了ORR活性。氮摻雜的碳基催化劑在ORR方面也展現(xiàn)出優(yōu)異的活性和穩(wěn)定性。本論文根據(jù)表面偏析的原理,制備過(guò)渡金屬氮化物為核,鉑為殼的核殼結(jié)構(gòu)ORR催化劑。結(jié)合物性表征和電化學(xué)表征的結(jié)果,分析催化劑中鉑殼層厚度和核納米粒子對(duì)氧還原催化性能的影響,闡明相關(guān)的催化機(jī)理,以期掌握核殼催化劑的結(jié)構(gòu)調(diào)控方法,開(kāi)發(fā)出高效穩(wěn)定且廉價(jià)的PEMFCs催化材料。主要研究?jī)?nèi)容如下:(1)通過(guò)浸漬還原法制備了初級(jí)產(chǎn)品,然后在氨氣中退火處理,最后在酸溶液中采用電化學(xué)去合金法得到一系列的N-Fe M@Pt/C(M=Mo、V、W)核殼催化劑。(2)通過(guò)調(diào)節(jié)前驅(qū)體中各元素的摩爾比來(lái)制備不同鉑殼層厚度的催化劑,并采用循環(huán)伏安法及線性掃描伏安法評(píng)價(jià)其催化性能。結(jié)果顯示,隨著鉑殼層厚度的減小,催化劑的電化學(xué)比表面積和質(zhì)量活性(0.9V vs.RHE)逐漸增加。相對(duì)于商業(yè)Pt/C而言,本論文制備的所有催化劑在質(zhì)量活性上都大幅提高,特別是N-Fe_5Mo_1@Pt_3/C催化劑,它的質(zhì)量活性甚至達(dá)到Pt/C的18.9倍。(3)通過(guò)調(diào)節(jié)元素種類制備了不同核納米粒子催化劑,并研究了5000圈循環(huán)伏安掃描前后的ORR穩(wěn)定性。結(jié)果表明,它們初始的ORR活性順序?yàn)镹-Fe_5Mo_1@Pt_3/CN-Fe_5V_1@Pt_3/CN-Fe_5W_1@Pt_3/C。在5000圈循環(huán)掃描之后,所有催化劑的ORR活性都有所退化,但相比于初始的Pt/C依舊展現(xiàn)出更高的活性。ORR活性退化的原因有兩種:一是金屬粒子的團(tuán)聚或脫離;二是不斷的循環(huán)伏安掃描后,由電化學(xué)去合金法產(chǎn)生的空位被附近的鉑原子填充。
[Abstract]:In proton exchange membrane fuel cell (PEMFCs), platinum is the best known catalyst for oxygen reduction, but its slow oxygen reduction kinetics, limited storage and high price seriously hinder the commercialization of PEMFCs. Therefore, low platinum and even non-platinum ORR catalysts have been widely studied. Recent studies show that the core-shell structure not only reduces the platinum loading of the catalyst, but also improves the ORR activity. Nitrogen-doped carbon-based catalysts also showed excellent activity and stability in ORR. In this paper, based on the principle of surface segregation, a core-shell structure ORR catalyst with transition metal nitride as core and platinum as shell was prepared. Based on the results of physical and electrochemical characterization, the effects of platinum shell thickness and nuclear nanoparticles on the catalytic performance of oxygen reduction were analyzed, and the related catalytic mechanisms were elucidated in order to master the structural control methods of core-shell catalysts. A high efficient, stable and cheap PEMFCs catalytic material was developed. The main research contents are as follows: (1) Primary products were prepared by impregnation reduction method and then annealed in ammonia gas. Finally, a series of core-shell catalysts with different thickness of platinum shell layer were prepared by adjusting the molar ratio of the elements in the precursor by electrochemical dealloying method in acid solution. The catalytic performance was evaluated by cyclic voltammetry and linear scanning voltammetry. The results showed that the electrochemical specific surface area and mass activity of the catalyst increased with the decrease of the thickness of platinum shell. Compared with commercial Pt/C, the mass activity of all the catalysts prepared in this paper is greatly improved, especially the mass activity of N-Fe_5Mo_1@Pt_3/C catalyst, which is 18.9 times higher than that of Pt/C. The stability of ORR before and after 5000 cycle cyclic voltammetry scanning was studied. The results show that their initial ORR activity is in the order of N-Fe5MoM\ ORR\ After the 5000 cycle scanning, the ORR activity of all the catalysts degenerated, but there were two reasons for the degradation of the activity of ORR than that of the initial Pt/C: the first was the agglomeration or detachment of metal particles; Second, after continuous cyclic voltammetry, the vacancies produced by electrochemical dealloying are filled with nearby platinum atoms.
【學(xué)位授予單位】：中國(guó)礦業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：O643.36;TM911.4

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本文編號(hào)：1933930