本文關(guān)鍵詞：Fe,Co元素?fù)诫s的納米多孔Pt-Al金屬間化合物及氧還原性能　出處：《吉林大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 燃料電池 納米多孔合金 氧還原 催化活性 催化穩(wěn)定性

【摘要】：在環(huán)境污染日益嚴(yán)重,化石燃料極度匱乏的今天,尋找一種儲(chǔ)量大、成本低、環(huán)境友好的新型能源是解決環(huán)境與能源問題的關(guān)鍵。而在眾多的新型能源中,低溫質(zhì)子交換膜(PEM)燃料電池又以能量轉(zhuǎn)換效率高、污染小、運(yùn)行速度快等優(yōu)點(diǎn)廣泛應(yīng)用于發(fā)電、汽車、便攜設(shè)備等領(lǐng)域,成為了化石燃料的有力替代者。因此,如何提高燃料電池的性能來推動(dòng)它的進(jìn)一步發(fā)展成為了一個(gè)備受矚目的課題。然而,目前商用的燃料電池陰極催化劑Pt/C的活性和耐久性很大程度上限制了燃料電池的發(fā)展。因?yàn)檫@種催化劑在反應(yīng)過程中對(duì)中間產(chǎn)物的吸附能過高,降低了它的催化活性;在長期使用過程中不斷發(fā)生粗化和剝落,影響了它的使用壽命。且貴金屬Pt的成本和儲(chǔ)量也制約了它的應(yīng)用。因此,我們急需尋找一種價(jià)格低廉且催化活性高、穩(wěn)定性好的新型催化劑來代替Pt/C催化劑來改善燃料電池的性能。近幾年研究者們最常用的方法是合金化法,即向Pt中加入過渡族元素M,如Fe、Co、Ni等,制備成Pt-M/Pt二元合金來改善催化劑的性能。這種合金催化劑雖然具有比Pt/C更高的催化活性,但在酸性電解質(zhì)中依然會(huì)發(fā)生擴(kuò)散和溶解,從而大大降低了催化劑的穩(wěn)定性。因此我們對(duì)這種二元合金進(jìn)行了改進(jìn),先采用合金化法制備Pt-M-Al三元合金,再采用去合金化法使這種三元合金形成納米多孔結(jié)構(gòu)。這種納米多孔結(jié)構(gòu)所具有的禁閉效應(yīng)、負(fù)曲率效應(yīng)和雙電荷電層交疊效應(yīng)能夠?qū)﹄姶呋鸬斤@著的促進(jìn)作用。因此,本論文將圍繞這種納米多孔三元合金在氧還原反應(yīng)中的催化性能展開研究,其主要的研究內(nèi)容及結(jié)果如下:1、納米多孔(Pt1-xFex)3Al/Pt金屬間化合物的合成及其催化性質(zhì)的研究大量的研究結(jié)果表明,Pt-Fe合金雖具有比Pt/C更高的催化活性,但催化穩(wěn)定性不足。因此,我們采用兩步制備法,先通過合金化的方法合成母合金Pt10Fe2Al88,再采用去合金化法合成納米多孔(Pt1-xFex)3Al/Pt金屬間化合物。這種金屬間化合物具有三維互通的雙模式孔結(jié)構(gòu),且具有優(yōu)異的電催化性能。在0.9 V(相對(duì)于標(biāo)準(zhǔn)氫電極電位)的電位下,納米多孔(Pt1-xFex)3Al/Pt金屬間化合物的比活性和質(zhì)量活性分別為3.97 m A cm Pt-2和1.94 A mgpt-1,分別是目前商用的Pt/C催化劑(0.39 m A cmPt-2和0.13A mgpt-1)的10.2倍和14.9倍。在長達(dá)40,000圈的循環(huán)過后,其半波電位(ΔE1/2)僅向左偏移15 m V,電化學(xué)活性面積(ECSA)仍剩余74%。這種優(yōu)異的催化活性和穩(wěn)定性來自于Fe和Al產(chǎn)生的壓縮應(yīng)變和配體效應(yīng)。二者的相互作用使Pt原子的d帶中心發(fā)生了顯著下移,同時(shí)抑制了表面Pt原子的擴(kuò)散和演變,保護(hù)了內(nèi)部Fe和Al不被腐蝕,從而穩(wěn)固了該催化劑的催化活性。這使得納米多孔(Pt1-xFex)3Al/Pt金屬間化合物成為了下一代燃料電池陰極催化劑的有力候選者。2、納米多孔(Pt_(1-x)Co_x)_3Al/Pt金屬間化合物的合成及其催化性質(zhì)的研究基于上一個(gè)工作中我們對(duì)Pt-Fe合金體系改良后取得的成功,我們同樣對(duì)Pt-Co合金進(jìn)行了改進(jìn)。采用同樣的合金/去合金化法,我們制備了納米多孔(Pt_(1-x)Co_x)_3Al/Pt金屬間化合物,并對(duì)其進(jìn)行了一系列的結(jié)構(gòu)和性能的表征。結(jié)果表明,這種納米多孔陰極催化劑在0.9 V(相對(duì)于標(biāo)準(zhǔn)氫電極電位)的半波電位(ΔE1/2)為0.931V,比活性為3.50 m A cmPt-2,質(zhì)量活性為1.72 A mgpt-1,分別是商用Pt/C催化劑(0.39 m A cmPt-2和0.13 A mgpt-1)的9.0倍和13.2倍。在50,000圈的長時(shí)間循環(huán)過后,其半波電位僅向左偏移13 m V,電化學(xué)活性面積(ECSA)仍剩余65%,質(zhì)量活性仍保留61%。由此可見,納米多孔(Pt1-xCox)3Al金屬間化合物同樣也可以作為陰極催化劑使用于燃料電池中。更重要的是,上述結(jié)果表明,這種三元催化劑的設(shè)計(jì)理念和合成方法不僅適用于Pt-Fe體系,也同樣適用于Pt-Co體系,在未來還可以向更多的合金體系發(fā)展,為陰極催化劑提供更多的可能。
[Abstract]:In the increasingly serious environmental pollution, fossil fuel shortage today, looking for a kind of large reserves, low cost, environmentally friendly new energy is the key to solve the problems of environment and energy. But in many new energy, low temperature proton exchange membrane fuel cell (PEM) and the energy conversion efficiency, low pollution. Fast is widely used in power generation, automotive, portable equipment and other fields, has become a powerful alternative to fossil fuels. Therefore, how to improve the performance of the fuel cell to promote the further development of it has become a high-profile topic. However, the current commercial Pt/C fuel cell cathode catalyst activity and durability largely restricted the development of fuel cell. Because of this kind of catalyst in the reaction process of adsorption of the intermediate products can be too high, reduce its activity; in the long-term use to process Coarsening and spalling, affect the service life of it. And the noble metal Pt and the cost of reserves is also restricted its application. Therefore, we are looking for a low price and high catalytic activity, good stability of the performance of a new catalyst instead of Pt/C catalyst to improve the fuel cell. In recent years, researchers most the commonly used method is the alloying method, adding M to Pt transition elements, such as Fe, Co, Ni, the performance of prepared Pt-M/Pt two yuan to improve the alloy catalyst. This alloy catalyst has higher catalytic activity than the Pt/C, but will still occur in acidic electrolyte diffusion and dissolution. Thus greatly reduce the stability of the catalyst. So we made improvement of the two yuan to three yuan alloy, preparation of Pt-M-Al alloys by alloying method, then the dealloy method makes the three element alloy forming nanoporous structure. The nano meter The confinement effect of pore structure with the negative curvature effect and electric double layer overlap effect to significant effect on Electrocatalytic. Therefore, this paper will focus on the three nanometer porous alloy has been studied in the catalytic performance of oxygen reduction reaction, the main research contents and results are as follows: 1. Nano porous (Pt1-xFex) on the synthesis and catalytic properties of a large number of research results of 3Al/Pt intermetallic compounds show that Pt-Fe alloy has higher catalytic activity than Pt/C, but the catalytic stability is insufficient. Therefore, we use two step preparation method, method by alloying synthesis of master alloy Pt10Fe2Al88, and then used to alloy the method of synthesis of nano porous 3Al/Pt intermetallic compound (Pt1-xFex) dual mode. The porous structure of the intermetallic compound has a three-dimensional interconnected, and has excellent electrocatalytic properties. In 0.9 V (relative to the standard hydrogen power Potential) potential, nano porous 3Al/Pt intermetallic compound (Pt1-xFex) specific activity and quality activity were 3.97 m and 1.94 A cm Pt-2 A mgpt-1, respectively, the current commercial Pt/C catalyst (0.39 m A cmPt-2 and 0.13A mgpt-1) 10.2 times and 14.9 times. After 40000 cycles and the half wave potential (E1/2) only left 15 m offset V, electrochemical active area (ECSA) still remaining 74%. the excellent catalytic activity and stability from the Fe and the Al compression strain and the ligand effect. The interaction between the two Pt atoms in the d band heart changed significantly down, at the same time inhibition of diffusion and evolution of surface Pt atoms, Fe and Al do not protect the internal corrosion, thus enhancing the catalytic activity of the catalyst. The nano porous 3Al/Pt intermetallic compound (Pt1-xFex) has become a strong candidate for the next generation of fuel cell cathode catalyst .2, nano porous (Pt_ (1-x) Co_x) on the synthesis and catalytic properties of _3Al/Pt intermetallic compounds on the basis of the previous work we made of Pt-Fe alloy modified system after the success, we also of Pt-Co alloy was improved. The alloying to the same alloy /, we prepared nano porous. Preparation of (Pt_ (1-x) Co_x) _3Al/Pt intermetallic compounds, and characterized the structure and properties of a series. The results show that the nano porous cathode catalyst at 0.9 V (relative to the standard hydrogen electrode potential) of the half wave potential (E1 /2) 0.931V, A cmPt-2 specific activity was 3.50 m the quality and activity of 1.72 A mgpt-1, respectively, is a commercial Pt/C catalyst (0.39 m and 0.13 A cmPt-2 A mgpt-1) 9 times and 13.2 times. After a long time 50000 cycles, the half wave potential only left 13 m offset V, electrochemical active area (ECSA) still remaining 65%, quality The activity remains so 61%. (Pt1-xCox), nano porous 3Al intermetallic compounds can also be used as cathode catalyst in fuel cells. More importantly, the results show that the design concept of this kind of three yuan catalyst and synthesis method is not only applicable to the Pt-Fe system, also applies to the Pt-Co system, but also in the future to develop more alloy system, provide more possibility for the cathode catalyst.

【學(xué)位授予單位】：吉林大學(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)：1437043