本文選題：空氣電極催化劑　切入點(diǎn)：二氧化錳　出處：《哈爾濱工業(yè)大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：陰極催化劑是限制鋰空氣電池性能的一個決定性因素�，F(xiàn)有的高效催化劑大部分是貴金屬催化劑，其價格昂貴且儲量有限。過渡金屬氧化物價格低廉且易于制備，作為氧電極催化劑引起了廣泛關(guān)注。本文研究重點(diǎn)是氧化錳、氧化鈷和氧化鈷-氧化錳復(fù)合材料在中性電解液中的ORR催化性能。 在電化學(xué)測試中，工作電極首先選擇了空氣擴(kuò)散電極，但是由于空氣擴(kuò)散電極導(dǎo)電性差，且手工壓制電極的重現(xiàn)性不好，所以工作電極最終選用以催化劑修飾的玻碳電極。本文中LSV曲線在-0.6V左右出現(xiàn)ORR電流峰，所以以該電位下的電流密度表征催化劑性能。 本文采用靜電紡絲法制備了氧化錳催化劑，并對其電催化性能進(jìn)行了研究。靜電紡絲產(chǎn)物為Mn3O4，其催化性能很低，故選用水熱法制備氧化錳材料。采用水熱法制備氧化錳，以過硫酸銨為氧化劑，比較了反應(yīng)溫度分別為120oC、140oC、160oC和180oC，反應(yīng)時間分別為6h、12h和24h時產(chǎn)物的催化性能。反應(yīng)溫度為120oC時材料XRD衍射峰很低且形貌呈現(xiàn)塊狀，其余反應(yīng)溫度下制備出材料均為β-MnO2納米線。在反應(yīng)溫度為140oC、反應(yīng)時間為12h時材料的催化性能最好，電流密度高達(dá)-29.07mA·cm-2。為了比較-MnO2與β-MnO2的催化性能，以高錳酸鉀為氧化劑制備氧化錳。同樣進(jìn)行反應(yīng)溫度和反應(yīng)時間的選擇，不同溫度和時間條件下制備的材料均為-MnO2納米線，隨著反應(yīng)時間的延長，，材料的長度增大。在反應(yīng)溫度為120oC、反應(yīng)時間為12h時，-MnO2催化活性最高，電流密度高達(dá)-34.50mA·cm-2。以兩種材料的最佳反應(yīng)條件比較，-MnO2的催化活性高于β-MnO2。因此，選擇以-MnO2為基體進(jìn)行Co元素的摻雜。 對-MnO2摻雜之前首先研究氧化鈷的性能。以硝酸鈷為靜電紡絲液主鹽，在500oC燒結(jié)得到塊狀Co3O4，其電流密度為-1.18mA·cm-2。水熱法制備出聚合為塊狀的Co3O4，加入分散劑PVP和PEG，PEG能夠使材料分散，但是兩者都不能提高材料的催化性能。最佳反應(yīng)時間為12h，反應(yīng)溫度為120oC，電流密度達(dá)到-3.74mA·cm-2。與靜電紡絲法制備的Co3O4相比水熱法制備的Co3O4電催化活性較高。以硝酸鈷為Co元素來源，采用水熱法向-MnO2中摻雜摩爾分?jǐn)?shù)分別為2%、5%和10%的Co元素，能譜測試表明材料中Co與Mn的比例與原料摻雜比例相當(dāng)，但是復(fù)合催化劑電流密度與-MnO2相比反而下降。直接將-MnO2與Co3O4材料混合作為催化劑，其電流密度與-MnO2相比也降低。本文中的摻雜和混合催化劑都沒有提高材料的催化性能。
[Abstract]:Cathode catalyst is a decisive factor in limiting the performance of lithium-air battery. Most of the available high-efficient catalysts are precious metal catalysts, which are expensive and have limited reserves. Transition metal oxides are cheap and easy to prepare. As a catalyst of oxygen electrode, this paper focuses on the ORR catalytic properties of manganese oxide, cobalt oxide and cobalt oxide / manganese oxide composites in neutral electrolyte. In electrochemical measurement, air diffusion electrode is first selected as working electrode, but because of the poor conductivity of air diffusion electrode and the poor reproducibility of manually pressed electrode, In this paper, the LSV curve of glassy carbon electrode modified by catalyst appears the peak of ORR current at -0.6 V, so the current density at this potential is used to characterize the performance of the catalyst. In this paper, manganese oxide catalyst was prepared by electrospinning method, and its electrocatalytic activity was studied. The product of electrostatic spinning was Mn3O4, and its catalytic activity was very low. Therefore, the hydrothermal method was used to prepare manganese oxide material, and the hydrothermal method was used to prepare manganese oxide. Using ammonium persulfate as oxidant, the catalytic properties of the product were compared at 120oC 140oC and 180oC, respectively, and the reaction time was 6h / 12h and 24h respectively. The XRD diffraction peak of the material was very low and the morphology was block when the reaction temperature was 120oC. The other materials were 尾 -MnO _ 2 nanowires at the reaction temperature of 140 OC and reaction time of 12 h, and the current density was up to -29.07 Ma 路cm ~ (-2). In order to compare the catalytic properties of -MnO _ 2 with 尾 -MnO _ 2, the catalytic properties of 尾 -MnO _ 2 and 尾 -MnO _ 2 were compared. Manganese oxide was prepared by using potassium permanganate as oxidant. Similarly, the reaction temperature and reaction time were selected. The materials prepared under different temperature and time were -MnO2 nanowires, and with the increase of reaction time, When the reaction temperature is 120oC and the reaction time is 12h, the catalytic activity is the highest and the current density is up to -34.50mA 路cm-2.Compared with the optimum reaction conditions, the catalytic activity of the two materials is higher than that of 尾 -MnO2.Therefore, when the reaction temperature is 120oC and the reaction time is 12h, the catalytic activity of MNO _ 2 is higher than that of 尾 -MnO _ 2. The Co element was doped with -MnO2 as substrate. The properties of cobalt oxide were studied before doping of -MnO2. Bulk Co _ 3O _ 4 was sintered at 500oC with a current density of -1.18mA 路cm ~ (-2) using cobalt nitrate as the main salt of electrospinning solution. Co _ 3O _ 4 was prepared by hydrothermal method, and the dispersant PVP and PEGG were added to disperse the material. But neither of them can improve the catalytic performance of the materials. The optimum reaction time is 12h, the reaction temperature is 120oC, the current density is -3.74mA 路cm-2.The electrocatalytic activity of Co3O4 prepared by hydrothermal method is higher than that of Co3O4 prepared by electrospinning. Cobalt nitrate is the source of Co. The molar fraction of Co doped to -MnO2 by hydrothermal method is 2% and 10%, respectively. The results of energy spectrum analysis show that the ratio of Co to mn in the material is the same as that of raw material. However, the current density of the composite catalyst is lower than that of -MnO2. The current density of the composite catalyst mixed directly with Co3O4 is also lower than that of -MnO2. Neither the doped catalyst nor the mixed catalyst in this paper has improved the catalytic performance of the catalyst.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TM911.41;O643.36

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 李小紅;古訓(xùn)玖;江向平;陳超;涂娜;;納米β-MnO_2空心球的可控制備及其催化性能研究[J];中國陶瓷;2010年10期

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