本文選題：鉭氧化物 + 單晶�。� 參考：《武漢理工大學》2015年碩士論文

【摘要】：微納單晶結構由于其接近理想晶體結構的特點,由于沒有晶界對載流子的散射,其具有良好的電荷傳輸性能,在很多方面有著良好的應用前景。由于眾多化學反應過程與表面結構息息相關,晶體的表面結構由于各向異性的原因與其表面晶面關系密切,故而改變晶體的表面晶面曝露是對微納晶體材料自身性能改良的重要手段之一,獲得具有新型特別是高能晶面曝露的微納晶體材料往往意味著材料的表面活性的增強或者化學反應的選擇性的改變。鉭氧化物是一類重要的功能材料,在介電,涂層,催化等方面有著很廣泛的應用。但現(xiàn)有的鉭氧化物材料基本是無定形或者多晶形態(tài),對單晶結構的鉭氧化物及其晶面的研究并沒有系統(tǒng)的研究,為了獲得單晶結構的鉭氧化物并且通過其進一步研究鉭氧化物晶體的晶面配置,使高能面的曝露比例增加,獲得高反應活性的鉭氧化物,我們通過構建強酸-弱酸混合反應體系來控制Ta5+離子水解,建立鉭氧化物的準平衡生長環(huán)境,在溶劑熱條件下獲得一種具有全新元素組成的的鉭氧氯立方微晶(TaO2.18Cl0.64 MCs)。該TaO2.18Cl0.64 MCs的組成通過XRD、XPS并結合XRF進行表征;通過結構擬合粉末X射線衍射的數(shù)據(jù)模擬了Ta O2.18Cl0.64 MCs的晶體結構,發(fā)現(xiàn)由于鹵素原子對氧原子取代造成了該TaO2.18Cl0.64 MCs中存在著空位并在一定范圍內保持了長程有序的周期性,具有超結構(super structure)的特點。本論文系統(tǒng)研究了該TaO2.18Cl0.64 MCs的形成機理并考察了其光吸收性質與光催化產氫性能,結果發(fā)現(xiàn)該TaO2.18Cl0.64MCs對波長小于300 nm的光具有較強的富集能力以及快速的電荷傳輸特性,并表現(xiàn)出比商品氧化鉭和單晶納米棒組成的氧化鉭分級結構更高的光催化產氫性能。根據(jù)我們對β相氧化鉭不同晶面表面能的第一性原理的計算結果,在目前已獲得的Ta2O5曝露的{0 0 1}、{0 1 0}和{1 0 0}三種晶面中,{0 0 1}(氧化鉭中具有3.9?晶面間距的晶面)具有最高的表面能。為了提高{0 0 1}晶面曝露的面積,我們以制備的鉭氧氯立方微晶為反應物,通過煅燒的方式獲得氧化鉭立方微晶(Ta2O5 MCs)。其曝露的{0 0 1}晶面占微晶總面積的1/3,遠高于文獻中已報道的氧化鉭材料。本論文中我們詳細探討了由TaO2.18Cl0.64 MCs到Ta2O5 MCs的熱轉變過程,闡明了Ta2O5 MCs的形成機理,并考察了該Ta2O5 MCs的光催化產氫性能。結果顯示具有較高的{0 0 1}晶面曝露比例的Ta2O5MCs表現(xiàn)出遠遠高于已報道的Ta2O5單晶納米棒的單位比表面活性。
[Abstract]:Because of its close to ideal crystal structure and no scattering of carriers by grain boundaries, micronanocrystals have good charge transport performance and have good application prospects in many fields. Because many chemical reaction processes are closely related to the surface structure, the surface structure of the crystal is closely related to the surface crystal surface due to anisotropy. Therefore, changing the surface exposure of crystals is one of the important ways to improve the properties of micronanocrystalline materials. Obtaining new micronanocrystalline materials with high energy surface exposure often means the enhancement of the surface activity of the materials or the change of the selectivity of chemical reactions. Tantalum oxide is a kind of important functional materials, which is widely used in dielectric, coating, catalysis and so on. However, the existing tantalum oxide materials are amorphous or polycrystalline, and there is no systematic study on the single crystal structure of tantalum oxide and its crystal plane. In order to obtain tantalum oxide with single crystal structure and further study the crystal plane configuration of tantalum oxide crystal, the exposure ratio of high energy surface is increased, and tantalum oxide with high reactive activity is obtained. In order to control the hydrolysis of Ta _ 5 ion by constructing a mixed reaction system of strong acid and weak acid, the quasi-equilibrium growth environment of tantalum oxide was established. A new kind of tantalum oxychloride cubic microcrystal TaO2.18Cl 0.64 MCsN was obtained under solvothermal conditions. The composition of TaO2.18Cl0.64 MCs was characterized by XRDX XPS and XRF, and the crystal structure of TaO2.18Cl0.64 MCs was simulated by fitting the X-ray diffraction data of TaO2.18Cl0.64 MCs. It is found that the substitution of halogen atoms for oxygen atoms leads to the existence of vacancies in the TaO2.18Cl0.64 MCs and maintains the periodicity of long term order in a certain range, which is characterized by superstructure super structure. In this paper, the formation mechanism of TaO2.18Cl0.64 MCs has been systematically studied, and its photoabsorption and photocatalytic hydrogen production properties have been investigated. The results show that TaO2.18Cl0.64MCs have strong enrichment ability and fast charge transfer property for light with wavelength less than 300 nm. Tantalum oxide has higher photocatalytic hydrogen production performance than commercial tantalum oxide and single crystal nanorods. According to the first principle calculation results of the surface energy of 尾 phase tantalum oxide on different surfaces, {0 01}, {0 10} and {100} (in tantalum oxide), {0 01} (in tantalum oxide) have been obtained in the three kinds of exposed faces of Ta 2O 5, {0 01}, {0 10} and {100}, and {0 01} (tantalum oxide) have 3. 9? The surface energy of the crystal surface is the highest. In order to increase the exposure area of {001} crystal plane, the prepared tantalum oxychloride cubic crystal was used as reactant to obtain tantalum oxide cubic crystal (Ta _ 2O _ 5) MCsO _ 5 by calcination. The exposed {001} faces account for 1 / 3 of the total microcrystalline area, which is much higher than that of the reported tantalum oxide materials in the literature. In this paper, the thermal transition from TaO2.18Cl0.64 MCs to Ta2O5MCs is discussed in detail, the formation mechanism of Ta2O5MCs is elucidated, and the photocatalytic hydrogen production of Ta2O5MCs is investigated. The results show that the unit specific surface activity of Ta _ 2O _ 5 MCs with higher exposure ratio of {0.01} faces is much higher than that of reported Ta _ 2O _ 5 nanorods.
【學位授予單位】：武漢理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TQ116.2;O643.36

【參考文獻】

相關博士學位論文 前1條

1 郭永解;壓電晶體磷酸三鎵的生長、性能與應用研究[D];山東大學;2013年

，

本文編號：2014568