本文關(guān)鍵詞：非貴金屬氧化物的設(shè)計(jì)、合成與電催化析氧反應(yīng)研究　出處：《中國(guó)科學(xué)技術(shù)大學(xué)》2017年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 析氧反應(yīng) 非貴金屬電催化劑 非晶電催化劑 電子性質(zhì) 同步輻射

【摘要】：廣泛的清潔能源技術(shù)需要高效、耐用的析氧反應(yīng)電催化劑,其中以RuO2和IrO2為代表。但RuO2和IrO2具有昂貴和不穩(wěn)定的缺點(diǎn),因此非貴金屬析氧反應(yīng)電催化劑受到重視和發(fā)展,如基于鎳、鐵、鈷的氧化物。以這三種過(guò)渡金屬為模型,探索增強(qiáng)析氧反應(yīng)電催化劑性能的方法,十分重要。而設(shè)計(jì)高效、耐用的析氧反應(yīng)電催化劑的關(guān)鍵原則在于大量的活性位點(diǎn)、優(yōu)異的導(dǎo)電性以及穩(wěn)定的催化活性結(jié)構(gòu)。圍繞以上幾點(diǎn)設(shè)計(jì)原則,本文的主要研究?jī)?nèi)容如下:1、超聲化學(xué)法合成的高效、耐用的非晶鎳鐵氧化物/碳雜化析氧反應(yīng)電催化劑。非晶催化劑是一類研究較少的催化劑。但非晶材料具有成分分布均勻、缺陷多等特點(diǎn),作為析氧反應(yīng)電催化劑十分有利。即非晶催化劑與對(duì)應(yīng)的晶體催化劑相比,具有更多的催化活性位點(diǎn)。據(jù)報(bào)道,與晶體催化劑相比,非晶催化劑通常擁有更好的催化性能。然而,非晶催化劑一般導(dǎo)電性差,結(jié)構(gòu)也不穩(wěn)定,對(duì)電催化不利。而且非晶電催化劑的制備方法十分有限。有鑒于此,我們發(fā)現(xiàn),超聲化學(xué)的特點(diǎn)使其可以用來(lái)制備組成可調(diào)控的非晶鎳鐵氧化物/碳雜化析氧反應(yīng)電催化劑。產(chǎn)物不僅具有優(yōu)異的析氧反應(yīng)性能(包括催化活性與穩(wěn)定性),而且在一定程度上克服了非晶催化劑導(dǎo)電性差和不穩(wěn)定的缺點(diǎn)�；谕捷椛涞腦射線表征揭示了,非晶鎳鐵氧化物/碳雜化催化劑中,優(yōu)異的性能來(lái)自于其中大量的氧空位、金屬配位不飽和位點(diǎn)、均相分散的鎳與鐵帶來(lái)的高效電荷傳遞、內(nèi)部的鎳單質(zhì)以及同時(shí)形成的碳骨架。2、獨(dú)特的含有高價(jià)態(tài)Co4+的層狀鈷酸鈉析氧反應(yīng)電催化劑。Co4+據(jù)報(bào)道是鈷基析氧反應(yīng)電催化劑真正的活性位點(diǎn)。有研究表明,增加催化劑中Co4+的含量可以提高其催化活性。但純Co4+不穩(wěn)定,而且理論計(jì)算研究表明Co4+在OER中并不具有最優(yōu)的吸附能。因此開(kāi)發(fā)含有較多穩(wěn)定的Co4+的混合價(jià)態(tài)鈷基電催化劑應(yīng)該是一種較好的方式。另外,電子性質(zhì)可以影響催化劑的性能。本文通過(guò)對(duì)一種層狀鈷酸鈉進(jìn)行簡(jiǎn)單的氧化,在保持層狀結(jié)構(gòu)不變和高價(jià)態(tài)Co4+相對(duì)穩(wěn)定的情況下,同時(shí)實(shí)現(xiàn)了對(duì)多種電子性質(zhì)包括氧化態(tài)、氧空位、導(dǎo)電性、鈷氧共價(jià)性的調(diào)控,從而協(xié)同增強(qiáng)了析氧反應(yīng)活性�；谕捷椛涞腦射線表征揭示了,層狀鈷酸鈉中鈷氧共價(jià)性的增強(qiáng)和導(dǎo)電性的提高是提升鈷酸鈉析氧反應(yīng)催化活性的關(guān)鍵。3、鹽酸氧化刻蝕法可以在保持金屬納米晶體外形不變的情況下,實(shí)現(xiàn)其尺寸調(diào)控,從而進(jìn)一步調(diào)控其尺寸依賴的表面等離激元及催化性質(zhì)。鹽酸氧化刻蝕的作用包括去除孿晶晶種和將金屬原子氧化回離子以降低離子的還原速率,從而在動(dòng)力學(xué)上實(shí)現(xiàn)對(duì)金屬納米晶體的尺寸調(diào)控。這為調(diào)控金屬納米晶體的尺寸提供了一種通用、簡(jiǎn)單、有效的方法。
[Abstract]:A wide range of clean energy technologies require an efficient and durable electrocatalyst for oxygen evolution reaction, which is represented by RuO2 and IrO2. However, RuO2 and IrO2 are expensive and unstable. Therefore, the electrocatalysts for non noble metal oxygen evolution have been emphasized and developed, such as oxides based on nickel, iron and cobalt. Taking these three transition metals as the model, it is very important to explore the method of enhancing the performance of the electrocatalyst for the enhanced oxygen evolution reaction. The key principles of designing highly effective and durable oxygen evolution reaction electrocatalysts are large number of active sites, excellent electrical conductivity and stable catalytic activity. Based on the above design principles, the main contents of this paper are as follows: 1. An efficient and durable amorphous nickel iron oxide / carbon hybrid oxygen evolution electrocatalyst synthesized by sonochemical method. Amorphous catalyst is a kind of less research catalyst. However, the amorphous material has the characteristics of homogeneous distribution and many defects. It is very beneficial to be used as an electrocatalyst for oxygen evolution reaction. That is, the amorphous catalyst has more catalytic activity sites than the corresponding crystal catalyst. It is reported that the amorphous catalyst usually has better catalytic performance compared with the crystal catalyst. However, the amorphous catalyst is generally poor in electrical conductivity, and the structure is unstable, which is unfavorable to electrocatalysis. Moreover, the preparation method of the amorphous electrocatalyst is very limited. In view of this, we found that the characteristics of ultrasonic chemistry can be used to prepare a controllable amorphous nickel iron oxide / carbon hybrid oxygen evolution electrocatalyst. The product not only has excellent oxygen evolution performance (including catalytic activity and stability), but also overcomes the shortcomings of poor conductivity and instability of amorphous catalyst to a certain extent. X - ray characterization based on synchrotron radiation reveals that amorphous iron nickel oxide / carbon hybrid catalyst, excellent performance from the high nickel and iron charged oxygen vacancy, a large number of metal coordination sites, unsaturated homogeneous dispersion of the transmission, the Ni internal and with the formation of the carbon skeleton. 2. A unique electrocatalyst with a high valence state of Co4+ in the stratified sodium cobalt acid oxygen evolution reaction. Co4+ is reported to be the real active site of the Co based oxygen evolution electrocatalyst. Some studies have shown that increasing the content of Co4+ in the catalyst can increase the catalytic activity of the catalyst. But the pure Co4+ is unstable, and the theoretical calculation shows that Co4+ does not have the best adsorption energy in OER. Therefore, it should be a better way to develop a mixed valence cobalt based electrocatalyst containing more stable Co4+. In addition, the properties of the catalyst can be affected by the electronic properties. Based on the simple oxidation of a layered cobalt acid sodium in the lamellar structure remains unchanged and valence Co4+ is relatively stable, while achieving the regulation of oxidation state, including oxygen vacancies, conductivity, cobalt oxide covalency for various electronic properties, thus synergistically enhanced the oxygen evolution reaction activity. The X ray characterization based on synchrotron radiation reveals that the enhancement of covalence and the conductivity of cobalt oxide in layered sodium carbonate is the key to enhance the catalytic activity of sodium cobaltate in oxygen evolution reaction. 3, HCl oxidation etching can keep the size of metal nanocrystal unchanged, and further regulate its size dependent surface plasmon and catalytic properties. The role of hydrochloric acid oxidation etching includes removing twin crystal seeds and oxidizing metal atoms back to ions to reduce the reduction rate of ions, thus realizing the size control of metal nanocrystals in dynamics. This provides a general, simple and effective method for the control of the size of metal nanocrystals.
【學(xué)位授予單位】：中國(guó)科學(xué)技術(shù)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：O643.36

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