本文關(guān)鍵詞： 尖晶石 氧還原反應(yīng) 異化效應(yīng) 密度泛函理論 吉布斯自由能圖　出處：《中國(guó)科學(xué):化學(xué)》2017年07期 　論文類型：期刊論文

【摘要】：基于實(shí)驗(yàn)發(fā)現(xiàn)尖晶石型催化劑晶體結(jié)構(gòu)的反轉(zhuǎn)會(huì)使其對(duì)氧還原反應(yīng)(ORR)的催化活性顯著提高,本文通過(guò)密度泛函理論(DFT)計(jì)算方法探究了尖晶石(Co_3O_4)-反尖晶石(Co_2FeO_4)-尖晶石(CoFe_2O_4、Fe_3O_4)的結(jié)構(gòu)反轉(zhuǎn)對(duì)氧還原催化活性提高的本質(zhì).計(jì)算發(fā)現(xiàn),隨著尖晶石結(jié)構(gòu)的反轉(zhuǎn),反尖晶石帶隙收窄,導(dǎo)電性增強(qiáng);費(fèi)米能級(jí)按"尖晶石(Co_3O_4)反尖晶石(Co_2FeO_4)尖晶石(CoFe_2O_4、Fe_3O_4)"的次序依次降低,氧還原第一步電子轉(zhuǎn)移能力逐漸變?nèi)?此外,由于反尖晶石Co_2FeO_4八面體占位,Fe、Co原子間的異化效應(yīng)使O O鍵的活化程度最為顯著.氧還原吉布斯自由能表明,若各催化劑電子傳輸能力相同,則反尖晶石Co_2FeO_4與尖晶石Co_3O_4較尖晶石CoFe_2O_4和Fe_3O_4更利于OH的脫附.綜合分析表明,反尖晶石Co_2FeO_4平衡了摻雜前后尖晶石催化劑的導(dǎo)電性、第一步電子轉(zhuǎn)移能力、對(duì)O_2的活化和OH的脫附能力,呈現(xiàn)出最優(yōu)的ORR催化活性.
[Abstract]:Based on the experimental results, it was found that the inversion of the crystal structure of spinel catalyst could significantly increase its catalytic activity for oxygen reduction reaction (ORR). By means of density functional theory (DFT) calculation, this paper explores the nature of the increase in catalytic activity for oxygen reduction of the structure inversion of the spinel Co3O4T / Co2FeO4C _ 2FeO _ 4 / S _ S _ 2FeO _ 4). It is found that with the inversion of the structure of the spinel, the stripe gap of the antispinel becomes narrower, and the structure inversion of the structure of the spinel CoFe2O4Fe3O4O4) increases the catalytic activity of oxygen reduction. The Fermi level decreased in the order of "spinel Cos _ 3O _ 4) anti-spinel Co2FeO _ 4) spinel CoFe2O4T _ 3O _ 4) and the first-step electron transfer capacity of oxygen reduction gradually weakened. Because of the dissimilation effect among the octahedron of Co_2FeO_4 octahedron, the activation of O / O bond is the most obvious. The Gibbs free energy of oxygen reduction shows that the electron transport capacity of the catalysts is the same. The desorption of OH by invert spinel Co_2FeO_4 and spinel Co_3O_4 is more favorable than that of spinel CoFe_2O_4 and Fe_3O_4. The comprehensive analysis shows that antispinel Co_2FeO_4 balances the conductivity of spinel catalyst before and after doping, and the first step electron transfer ability is obtained. The activation of O _ 2 and the desorption of OH showed the best ORR catalytic activity.
【作者單位】： 重慶大學(xué)化學(xué)化工學(xué)院;
【基金】：國(guó)家自然科學(xué)基金(編號(hào):21376284,21436003)資助項(xiàng)目
【分類號(hào)】：O643.36;TM911.4

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