本文選題：EOR + ORR��； 參考：《石河子大學(xué)》2015年碩士論文

【摘要】：直接乙醇燃料電池(DEFC)具有低污染、理論能量密度高、燃料來源廣泛、儲存和運輸方便等優(yōu)點,在便攜式電源、電動汽車等領(lǐng)域有廣范的應(yīng)用前景,對解決能源短缺和環(huán)境污染兩大難題有重大的意義。目前DEFC最常用的催化劑是Pt基催化劑,Pt基催化劑對乙醇電化學(xué)氧化(EOR)的活性不高,而且EOR反應(yīng)中產(chǎn)生的中間產(chǎn)物會造成催化劑中毒失活。因此,開發(fā)高活性的催化劑對DEFC的發(fā)展具有重要意義。而且,由于Pt的價格較高、儲量稀少,所以研究負載量低的Pt基催化劑或是非Pt催化劑已勢在必行。本文從催化劑的活性、穩(wěn)定性和制備成本三方面考慮,主要研究了以下內(nèi)容:(1)本文通過溶劑蒸發(fā)法制備了介孔Sn O2,然后利用乙二醇還原法制備了介孔Pt Sn O2/C電催化劑。通過X-射線衍射(XRD),X-射線光電子能譜分析(XPS)、透射電鏡(TEM)和電感耦合等離子體原子發(fā)射光譜(ICP-AES)等表征手段,對催化劑的形貌和組成元素進行表征。證明了介孔Sn O2和Pt納米粒子成功的固載在碳載體上。通過電化學(xué)性能測試可知,由于介孔Sn O2的加入,雖然催化劑的電化學(xué)表面積(ECSA)明顯降低了,但活性和抗中毒能力有明顯的提高,這是因為和普通的Pt Sn O2/C催化劑相比,介孔Sn O2和Pt納米粒子的接觸面積更大,相互作用也更強,提高了Pt活性位的催化能力,降低了中間產(chǎn)物在Pt活性位的覆蓋,減少了催化劑的失活,從而使催化劑的活性和穩(wěn)定性有了明顯的提高。(2)本文結(jié)合了囊泡模板法和化學(xué)還原法制備了中空結(jié)構(gòu)的Pd Cu納米球,在常溫下以水為溶劑,Vulcan XC-72碳黑為載體制備了中空Pd Cu/C催化劑。通過TEM和高角度環(huán)形暗場-掃描透射電子顯微鏡(HAADF-STEM)對催化劑進行表征,結(jié)果表明Pd Cu納米球是由Pd Cu納米粒子構(gòu)成,而且負載后的Pd Cu納米球仍然保持中空結(jié)構(gòu)。相應(yīng)的元素映射也證明了Pd、Cu兩種元素是均勻分布在中空球上。和Pd/C相比,Pd Cu/C催化劑對氧還原反應(yīng)(ORR)的催化活性顯著提高,經(jīng)過3000圈CV的穩(wěn)定性測試,Pd Cu/C催化劑的電流密度下降了24.8%,而且穩(wěn)定后的電流密度也遠高于Pd/C和Pt/C催化劑。中空Pd Cu/C催化劑具有更高的催化活性和穩(wěn)定性可歸因于兩方面:一方面,Cu的摻雜提高了Pd的分散度;另一方面,中空結(jié)構(gòu)的納米粒子和實心納米顆粒相比,前者的比表面積更大,提供的活性位也更多。(3)本文采用簡單的水熱法,在聚乙烯吡咯烷酮(PVP)、溴化鉀、四氯鉑酸鉀、氯鈀酸鈉、氯化銅體系中,通過控制鹽酸的量制備了就有高晶面的Pt Pd Cu凹面立方體。通過XRD表征證明了Pt Pd Cu/C-1和Pt Pd Cu/C-2兩種催化劑都存在合金相。通過對制備的Pt Pd Cu/C-1和Pt Pd Cu/C-2催化劑進行陰極ORR性能的測試,表明高指數(shù)晶面的Pt Pd Cu/C-1和Pt Pd Cu/C-2比Pt/C催化劑更優(yōu)異的催化活性。這主要歸因于其具有更大催化活性位(缺陷位)的高指數(shù)晶面以及Pt和其他金屬(Cu和Pd)形成合金對催化劑表面電子結(jié)構(gòu)的調(diào)變。
[Abstract]:Direct ethanol fuel cell (DEFC) has the advantages of low pollution, high theoretical energy density, wide range of fuel sources, convenient storage and transportation, and has a wide application prospect in portable power supply, electric vehicle and other fields. It is of great significance to solve the problems of energy shortage and environmental pollution. At present, the most commonly used catalyst for DEFC is the Pt based catalyst and the Pt based catalyst has low activity for the electrochemical oxidation of ethanol (EOR), and the intermediate product produced in the EOR reaction will lead to the deactivation of the catalyst. Therefore, the development of high activity catalyst is of great significance to the development of DEFC. Moreover, due to the high price of Pt and the scarcity of its reserves, it is imperative to study Pt based catalysts or non-Pt catalysts with low loading. The main contents are as follows: (1) in this paper, mesoporous Sno _ 2 was prepared by solvent evaporation, and then mesoporous Pt _ Sno _ 2 / C electrocatalyst was prepared by ethylene glycol reduction method. The morphology and composition of the catalyst were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and inductively coupled plasma atomic emission spectrometry (ICP-AES). It was proved that mesoporous Sno _ 2 and Pt nanoparticles were successfully immobilized on carbon support. According to the electrochemical performance test, although the electrochemical surface area (ECSA) of the catalyst decreased obviously, the electrochemical surface area (ECSA) of the catalyst was obviously decreased due to the addition of mesoporous Sno _ 2, but the activity and anti-poisoning ability of the catalyst were significantly improved, which was due to the comparison with the ordinary Pt / Sn _ 2 / C catalyst. The contact area between mesoporous Sno _ 2 and Pt nanoparticles is larger and the interaction is stronger. The catalytic ability of Pt active site is improved, the coverage of intermediate product in Pt active site is reduced, and the deactivation of catalyst is reduced. As a result, the activity and stability of the catalyst were improved obviously. (2) the hollow PD Cu nanospheres were prepared by using vesicle template method and chemical reduction method. Hollow PD Cu / C catalyst was prepared by using water as solvent Vulcan XC-72 carbon black at room temperature. The catalyst was characterized by TEM and high angle ring dark field-scanning electron microscopy (HAADF-STEM). The results showed that the PD Cu nanospheres were composed of PD Cu nanoparticles, and the supported PD Cu nanospheres remained hollow structure. The corresponding element mapping also proves that the two elements of PdCU are uniformly distributed on hollow spheres. Compared with PD / C, the catalytic activity of PD / Cu / C catalyst for oxygen reduction reaction (ORR) was significantly increased. The current density of PD / Cu / C catalyst decreased by 24.8T after 3000 cycles of CV stability test, and the current density after stabilization was much higher than that of PD / C and PtP / C catalysts. The higher catalytic activity and stability of hollow PD / Cu / C catalyst can be attributed to two aspects: on the one hand, the doping of Cu increases the dispersion of PD; on the other hand, the hollow structure nanoparticles are compared with solid nanoparticles. The former has larger specific surface area and more active sites. (3) in the system of polyvinylpyrrolidone (PVP), potassium bromide, potassium tetrachloroplatinate, sodium palladium chloride and copper chloride, a simple hydrothermal method is used. The Pt PD Cu concave cube with high crystal surface was prepared by controlling the amount of hydrochloric acid. XRD results show that there are alloy phases in both Pt PD Cu / C 1 and Pt PD Cu / C 2 catalysts. The cathodic ORR properties of Pt PD Cu / C 1 and Pt PD Cu / C 2 catalysts were tested. The results show that Pt PD Cu / C 1 and Pt PD Cu / C 2 have better catalytic activity than that of Pt / C catalyst. This is mainly attributed to the high exponent crystal surface with larger catalytic activity sites (defect sites) and the modulation of electronic structure on the surface of the catalyst formed by Pt and other metals (Cu and PD).
【學(xué)位授予單位】：石河子大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：O643.36;TM911.4

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