亞氧化鈦負(fù)載Pt、Pd和Pt-Tb催化劑對(duì)甲酸電氧化的催化性能研究
發(fā)布時(shí)間：2018-07-22 13:00
【摘要】：鉑、鈀及其合金催化劑在甲酸燃料電池中應(yīng)用廣泛,但作為傳統(tǒng)載體的碳材料存在易腐蝕、易氧化等缺點(diǎn),這在很大程度上限制了甲酸燃料電池的工作效率和性能。近年來(lái),非碳載體材料逐漸受到人們廣泛的關(guān)注。鈦黑作為一種新穎的非碳載體材料,因其高的電導(dǎo)率和在酸性以及堿性環(huán)境中較好的抗腐蝕性、抗氧化性和穩(wěn)定性,而有望成為甲酸燃料電池催化劑的候選載體。本論文以鈦黑為載體分別制備了負(fù)載Pt、Pd以及Pt-Tb雙金屬催化劑,并研究了它們?cè)诩姿犭娧趸^(guò)程中的催化性能。為關(guān)聯(lián)催化劑結(jié)構(gòu)與性能,采用X射線衍射(XRD)、透射電鏡(TEM)、X射線光電子能譜(XPS)等測(cè)試手段對(duì)催化劑的組成、結(jié)構(gòu)、形貌、晶粒大小及分布等物理化學(xué)性質(zhì)進(jìn)行表征;并運(yùn)用循環(huán)伏安法(CV)、計(jì)時(shí)電流法(CA)、線性掃描法(LSV)以及CO溶出伏安法(CO stripping)等電化學(xué)方法研究了催化劑對(duì)甲酸的電化學(xué)性能。論文主要分為3個(gè)部分:第一部分:以鈦黑、炭黑及TiO2為載體采用硼氫化鈉還原法分別制備了Pt/Ti4O7、Pt/C和Pt/TiO2催化劑。接觸角測(cè)試結(jié)果顯示,Ti4O7的疏水性是導(dǎo)致Pt納米粒子在Ti4O7載體上分散性不好,進(jìn)而造成粒子團(tuán)聚的一個(gè)重要原因。然而,以上3個(gè)催化劑對(duì)甲酸氧化的電化學(xué)測(cè)試結(jié)果表明,與Pt/C和Pt/TiO2催化劑相比,Pt/Ti4O7催化劑具有更高的催化活性和穩(wěn)定性。除了由于Ti4O7自身的高電導(dǎo)率之外,Ti4O7載體具有“金屬化”效應(yīng)是另一個(gè)重要的原因。第二部分:采用硼氫化鈉還原法制備了Pd/Ti4O7和Pd/C催化劑。TEM表征結(jié)果發(fā)現(xiàn),Pd金屬納米粒子均勻的分散在各載體上。電化學(xué)測(cè)試結(jié)果顯示,催化劑Pd/Ti4O7具有較高的電催化活性。用PDDA功能化載體鈦黑之后,采用硼氫化鈉還原法制備的Pd/PDDA-Ti4O7催化劑的電催化性能比Pd/Ti4O7催化劑的更高。XPS結(jié)果證實(shí),PDDA的作用是通過(guò)增加Ti4O7載體的“金屬化”效應(yīng),使得催化劑中金屬態(tài)Pd的含量增加,從而顯著改善了催化劑的活性。第三部分:以鈦黑為載體采用硼氫化鈉還原法合成了不同比例的Pt-Tb雙金屬催化劑。TEM結(jié)果顯示,Pt-Tb納米粒子在鈦黑載體上的分散性好,且較均勻。電化學(xué)測(cè)試結(jié)果表明,20%Pt-2.5%Tb/Ti4O7催化劑對(duì)甲酸電氧化的催化活性較高,且其對(duì)移除CO中毒中間體的性能也較好。進(jìn)一步研究表明,Tb的作用是能在更負(fù)的電位條件下促進(jìn)II CO中毒中間體發(fā)生氧化反應(yīng),從而解除了貴金屬Pt被占據(jù)的活性位點(diǎn),緩解了催化劑中毒的現(xiàn)象,即可以解釋為雙功能機(jī)理。
[Abstract]:Platinum, palladium and its alloy catalysts are widely used in formic acid fuel cells, but the carbon materials used as traditional carriers are easy to corrode and oxidize, which limits the efficiency and performance of formic acid fuel cells to a great extent. In recent years, non-carbon carrier materials have been paid more and more attention. As a novel non-carbon carrier material, titanium black is expected to be a candidate carrier for formic acid fuel cell catalysts due to its high conductivity and good corrosion resistance, oxidation resistance and stability in acidic and alkaline environments. In this paper, supported PtPd and Pt-Tb bimetallic catalysts were prepared with titanium black as the carrier, and their catalytic properties in the process of formic acid electrooxidation were studied. The composition, structure, morphology, grain size and distribution of the catalyst were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The electrochemical properties of the catalyst for formic acid were studied by cyclic voltammetry (CV), chronoamperometry (CA), linear scanning voltammetry (LSV) and CO stripping. The thesis is mainly divided into three parts: in the first part, the Pt / Ti _ 4O _ 7N _ t / C and Pt / TIO _ 2 catalysts were prepared by sodium borohydride reduction method with titanium black, carbon black and TIO _ 2 as the support. The contact angle test results show that the hydrophobicity of Ti _ 4O _ 7 is one of the important reasons leading to the poor dispersion of Pt nanoparticles on Ti _ 4O _ 7 support and thus to the agglomeration of the particles. However, the electrochemical measurements of the oxidation of formic acid over the above three catalysts showed that the catalytic activity and stability of PtTi4O7 catalysts were higher than those of Pt / C and PT / TIO _ 2 catalysts. Besides the high conductivity of Ti _ 4O _ 7, the metallization of Ti _ 4O _ 7 carrier is another important reason. Part two: PD / Ti _ 4O _ 7 and PD / Ti _ 4O _ 7 and PD / C catalyst 路TEM were prepared by sodium borohydride reduction method. Electrochemical measurements showed that PD / Ti _ 4O _ 7 catalyst had high electrocatalytic activity. After using PDDA functionalized carrier titanium black, PD / PDDA-Ti _ 4O _ 7 catalyst prepared by sodium borohydride reduction method has higher electrocatalytic performance than PD / Ti _ 4O _ 7 catalyst. XPS results show that the effect of PDDA is by increasing the "metallization" effect of Ti _ 4O _ 7 support. The content of PD in the catalyst was increased, and the activity of the catalyst was improved significantly. The third part: Pt-Tb bimetallic catalyst with different proportion was synthesized by sodium borohydride reduction method with titanium black as the carrier. The results of TEM showed that the dispersion of Pt-Tb nanoparticles on titanium black was good and uniform. The electrochemical test results show that the catalytic activity of Tb- / Ti _ 4O _ 7 catalyst is higher for formic acid electrooxidation, and the catalytic activity for removing CO poisoning intermediates is better than that of Tb- / Ti _ 4O _ 7 catalyst. Further studies show that Tb can promote the oxidation reaction of II CO poisoning intermediates under more negative potential, thus removing the active sites occupied by noble metals Pt, and alleviating the phenomenon of catalyst poisoning. It can be explained as the mechanism of double function.
【學(xué)位授予單位】：河南師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：O643.36;TM911.4
本文編號(hào)：2137544
[Abstract]:Platinum, palladium and its alloy catalysts are widely used in formic acid fuel cells, but the carbon materials used as traditional carriers are easy to corrode and oxidize, which limits the efficiency and performance of formic acid fuel cells to a great extent. In recent years, non-carbon carrier materials have been paid more and more attention. As a novel non-carbon carrier material, titanium black is expected to be a candidate carrier for formic acid fuel cell catalysts due to its high conductivity and good corrosion resistance, oxidation resistance and stability in acidic and alkaline environments. In this paper, supported PtPd and Pt-Tb bimetallic catalysts were prepared with titanium black as the carrier, and their catalytic properties in the process of formic acid electrooxidation were studied. The composition, structure, morphology, grain size and distribution of the catalyst were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The electrochemical properties of the catalyst for formic acid were studied by cyclic voltammetry (CV), chronoamperometry (CA), linear scanning voltammetry (LSV) and CO stripping. The thesis is mainly divided into three parts: in the first part, the Pt / Ti _ 4O _ 7N _ t / C and Pt / TIO _ 2 catalysts were prepared by sodium borohydride reduction method with titanium black, carbon black and TIO _ 2 as the support. The contact angle test results show that the hydrophobicity of Ti _ 4O _ 7 is one of the important reasons leading to the poor dispersion of Pt nanoparticles on Ti _ 4O _ 7 support and thus to the agglomeration of the particles. However, the electrochemical measurements of the oxidation of formic acid over the above three catalysts showed that the catalytic activity and stability of PtTi4O7 catalysts were higher than those of Pt / C and PT / TIO _ 2 catalysts. Besides the high conductivity of Ti _ 4O _ 7, the metallization of Ti _ 4O _ 7 carrier is another important reason. Part two: PD / Ti _ 4O _ 7 and PD / Ti _ 4O _ 7 and PD / C catalyst 路TEM were prepared by sodium borohydride reduction method. Electrochemical measurements showed that PD / Ti _ 4O _ 7 catalyst had high electrocatalytic activity. After using PDDA functionalized carrier titanium black, PD / PDDA-Ti _ 4O _ 7 catalyst prepared by sodium borohydride reduction method has higher electrocatalytic performance than PD / Ti _ 4O _ 7 catalyst. XPS results show that the effect of PDDA is by increasing the "metallization" effect of Ti _ 4O _ 7 support. The content of PD in the catalyst was increased, and the activity of the catalyst was improved significantly. The third part: Pt-Tb bimetallic catalyst with different proportion was synthesized by sodium borohydride reduction method with titanium black as the carrier. The results of TEM showed that the dispersion of Pt-Tb nanoparticles on titanium black was good and uniform. The electrochemical test results show that the catalytic activity of Tb- / Ti _ 4O _ 7 catalyst is higher for formic acid electrooxidation, and the catalytic activity for removing CO poisoning intermediates is better than that of Tb- / Ti _ 4O _ 7 catalyst. Further studies show that Tb can promote the oxidation reaction of II CO poisoning intermediates under more negative potential, thus removing the active sites occupied by noble metals Pt, and alleviating the phenomenon of catalyst poisoning. It can be explained as the mechanism of double function.
【學(xué)位授予單位】：河南師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：O643.36;TM911.4
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