發(fā)布時間：2018-02-24 17:15

  本文關(guān)鍵詞： 納米材料 TiO_2 光催化 復(fù)合結(jié)構(gòu) 異相結(jié)　出處：《浙江大學(xué)》2016年博士論文　論文類型：學(xué)位論文

【摘要】：過去幾十年來,隨著人類社會的發(fā)展,人口激增,全球化進程不斷推進,伴隨而來的環(huán)境污染與高能量消耗問題開始變得越來越突出。尋找治理污染的有效途徑,實現(xiàn)清潔可持續(xù)發(fā)展模式成為現(xiàn)代社會的共識。二氧化鈦(TiO_2)由于其穩(wěn)定性高,成本較低,環(huán)境友好,用途廣泛和優(yōu)異的光催化性能而引起研究者的重視,在光催化環(huán)境治理等諸多領(lǐng)域得到廣泛應(yīng)用。TiO_2納米粉體比表面積大,催化活性高,但容易團聚且難以完整回收,容易造成二次污染；TiO_2薄膜回收方便,可反復(fù)多次使用,無二次污染,但其制備工藝復(fù)雜,光催化性能不如粉體催化劑高,限制了其大規(guī)模產(chǎn)業(yè)化應(yīng)用。因此,制備工藝簡單、結(jié)合力好、光催化性能優(yōu)異的TiO_2薄膜的研發(fā)具有重要的科學(xué)研究意義和工程應(yīng)用價值。鈦金屬原位氧化工藝特點決定了金屬鈦基板與TiO_2薄膜之間的結(jié)合十分緊密,采用該技術(shù)已獲得納米管、納米線、納米棒、納米花等一/三維納米陣列TiO_2薄膜。本文致力于雙氧水直接氧化鈦金屬基板制備TiO_2薄膜的相結(jié)構(gòu)和納米形貌調(diào)控,通過“異相結(jié)”和“一/三維納米結(jié)構(gòu)”的有機組合,協(xié)同優(yōu)化TiO_2薄膜的光電催化性能,為TiO_2光催化在環(huán)境和能源領(lǐng)域的工程應(yīng)用打下基礎(chǔ)。本文首先總結(jié)了光催化工作原理,回顧了TiO_2作為光催化劑的研究現(xiàn)狀、已有的制備工藝、摻雜技術(shù)、相結(jié)構(gòu)調(diào)控、納米形貌調(diào)控,以及相關(guān)理論。在此基礎(chǔ)上,提出本文的研究背景,并闡述了本文主要研究思路。本文利用鈦金屬與特定雙氧水溶液反應(yīng)后得到的溶液作為前驅(qū)液,在鈦金屬基板上實現(xiàn)金紅石相TiO_2納米花單層膜的沉積,消除了薄膜與基板之間的TiO_2納米顆粒阻擋層。TiO_2單層膜的納米結(jié)構(gòu)(納米棒或者納米花)的形成可用定向粘附理論解釋,具體納米形態(tài)與鈦金屬基板的預(yù)處理工藝密切相關(guān)。采用稀硝酸替代混合酸對鈦基板進行清洗處理時,由于減少了混合酸酸洗導(dǎo)致的腐蝕點,TiO_2形核率下降,后續(xù)在已生長納米棒缺陷位置形核概率上升,因而有利于納米花而不是納米棒陣列的形成。系統(tǒng)研究了沉積溫度、時間,以及納米花薄膜后續(xù)熱處理對其光電性能的影響,結(jié)果表明,80℃沉積6h并經(jīng)后續(xù)450℃熱處理1h的納米花薄膜的光電催化降解水中若丹明B染料的效率是一種商用金紅石TiO_2納米顆粒薄膜的4.9倍,是商用P25 TiO_2納米顆粒薄膜的1.3倍。薄膜光電催化效率的提高可歸因于中間阻擋層的消除、納米花固有的高比表面積,以及單晶TiO_2納米棒導(dǎo)致的外加偏電壓作用下的高電子遷移率。本文使用鈦基板在高溫下原位真空熱氧化,成功制得了鈦基TiO_2納米線薄膜,研究了納米線陣列的生長過程及薄膜的結(jié)構(gòu)參數(shù),并探討了納米線的生長機理。通過降解水中染料羅丹明B的方式測試經(jīng)不同時間熱氧化處理后酸洗鈦片的光催化性能。薄膜結(jié)構(gòu)表征結(jié)果表明,一定真空條件下鈦片在750℃熱氧化5～10h后可以獲得大量直徑40～50 nm,長度3.0～5.0 μm的單晶金紅石結(jié)構(gòu)TiO_2納米線；使用H2O_2氧化鈦片表面預(yù)先獲得一層多孔非晶TiO_2薄層,可顯著影響納米線的生長。光催化性能測試結(jié)果表明,真空熱氧化處理1h獲得的扁平片狀納米結(jié)構(gòu)金紅石薄膜具有最高的光催化降解羅丹明B的能力；熱處理時間從5h延長到10h,得到的納米線金紅石薄膜的光催化性能有所提高。本文針對單位面積TiO_2有效擔(dān)載量的問題,在鈦基板上通過逐層沉積銳鈦礦/金紅石復(fù)合結(jié)構(gòu)納米棒、銳鈦礦溶膠-凝膠層和金紅石納米花的方式,最終得到一種具有“三明治”結(jié)構(gòu)的TiO_2復(fù)合薄膜。該復(fù)合薄膜總體相組成為79%銳鈦礦和21%金紅石,接近于商用P25 TiO_2；其禁帶寬度為3.0 eV。紫外光照下降解羅丹明B染料時,復(fù)合薄膜的準(zhǔn)一級反應(yīng)速率為12.3×10-3 min-1,明顯高于構(gòu)成薄膜的銳鈦礦/金紅石納米棒(3.9×10-3 min-1)、溶膠-凝膠銳鈦礦(0.3×10-3min-1)和金紅石納米花(4.7×10-3 min-1)的降解速率。研究結(jié)果表明,不同相組成和納米形貌的TiO_2薄膜的適當(dāng)組合,是提高其光催化活性的有效手段。為充分利用納米線薄膜中納米線之間的空間,提高薄膜的TiO_2有效擔(dān)載量,本文將納米線陣列薄膜浸沒于特定前驅(qū)液中,獲得一種納米分級結(jié)構(gòu)薄膜。該薄膜表面由均勻分布的銳鈦礦相TiO_2納米線主干和金紅石相TiO_2納米分支構(gòu)成。其中分支為單晶結(jié)構(gòu),隨著二次沉積時間的延長而逐漸長大。由于其獨特的形貌和相結(jié)構(gòu)的復(fù)合,薄膜具有特定能帶匹配的異相結(jié)結(jié)構(gòu),其高比表面積、獨特的分支形貌和混晶效應(yīng)使得薄膜的光能利用效率得到有效提升,光電響應(yīng)性能和光催化降解水溶液中有機物的性能得以顯著提高。為了進一步厘清異相結(jié)結(jié)構(gòu)在分支TiO_2納米薄膜中的作用,本文將銳鈦礦相TiO_2納米線薄膜分別置于一定濃度的TiCl4活TiF4溶液中，，成功制備了不同相組成的分級結(jié)構(gòu)TiO_2納米線薄膜。其中，TiCl4溶液體系中沉積得到的薄膜包含銳鈦礦/金紅石異相結(jié)復(fù)合結(jié)構(gòu)；而TiF4溶液體系中沉積得到的薄膜不包含異相結(jié)結(jié)構(gòu)。通過精確控制制備工藝,深入分析薄膜TiO_2擔(dān)載量、相組成和納米形態(tài)與光催化性能之間的關(guān)系,確認(rèn)了分支結(jié)構(gòu)TiO_2薄膜中“異相結(jié)”的重要作用。此外,還研究了陰離子摻雜的作用,復(fù)合薄膜在光催化應(yīng)用中存在的“自然時效”現(xiàn)象,以及復(fù)合薄膜對不同有機物的光催化降解特性。
[Abstract]:Over the past few decades, with the development of human society, population growth, accelerating process of globalization, accompanied by environmental pollution and high energy consumption problem has become increasingly prominent. Finding effective ways to control pollution, to achieve the sustainable development mode of modern clean become social consensus. Titanium dioxide (TiO_2) due to its high stability. Low cost, friendly environment, wide application and excellent photocatalytic performance caused by the attention of researchers, in the photocatalytic environmental governance and many other fields have been widely used.TiO_2 nano powder specific surface area, high catalytic activity, but it is easy to aggregate and difficult to complete recovery, easy to cause two pollution; convenient TiO_2 recycling film that can be used repeatedly, no two pollution, but the complex preparation process, photocatalytic properties as powder catalyst, limit its large-scale industrial application. Therefore, the preparation process Simple process, good adhesion, developing excellent photocatalytic properties of TiO_2 thin films is of great significance in scientific research and engineering application value. The titanium in situ oxidation characteristics determine the combination between titanium substrate and TiO_2 thin film is very close, the technology has been the nanotubes, nanowires, nanorods, nano flowers etc. a 3D / nano array TiO_2 films. This paper focuses on the direct regulation of phase structure and hydrogen peroxide titanium oxide nano morphology of TiO_2 thin films prepared by metal substrate system, through the organic combination of heterogeneous nodes "and" A / three-dimensional nano structure, the photoelectrocatalytic properties of TiO_2 thin films for collaborative optimization, TiO_2 photocatalytic lay the foundation in the environment and the energy field of the engineering application. This paper summarizes the principle of photocatalysis, reviews the research status of TiO_2 as photocatalyst, the preparation process, the doping technology, phase structure regulation, Nano morphology controlling, and the related theory. On this basis, puts forward the research background, and expounds the main research method of this dissertation. The solution reaction of titanium with a specific hydrogen peroxide solution as the precursor solution, deposition on titanium substrate of rutile phase TiO_2 nanoflower solid monolayer, eliminating the nano structure TiO_2 nanoparticles between the film and the substrate of the barrier layer.TiO_2 layer (nanorods or nanoflowers) can be explained by the formation of directional adhesion theory, the pretreatment process and the specific form of nano titanium metal substrate is closely related. By using dilute nitric acid instead of mixed acid cleaning treatment on titanium substrate, due to the decrease of the corrosion point of mixed acid wash the lead, the nucleation rate of TiO_2 decreased in the subsequent growth position of defect nucleation nanorods has probability rise, which is conducive to nano flowers instead of nanorod array formation. The time of deposition temperature, and the nano flower film following heat treatment effect on the photoelectric performance results indicate that the deposition of 6h and the subsequent 80 degrees 450 degrees of heat treatment of photocatalytic degradation of 1H in nanometer film if the efficiency of rhodamine B dye is 4.9 times of a commercial rutile TiO_2 nanoparticles film that is 1.3 times that of commercial P25 TiO_2 nanoparticle film. The film photoelectrocatalytic efficiency can be attributed to the middle barrier layer to eliminate the inherent nanoflower high specific surface area, and the applied bias voltage under high electron mobility of single crystal TiO_2 nanorods. This leads to the use of titanium substrate at high temperature in vacuum thermal oxidation and successfully prepared titanium based TiO_2 Nanowire Films, structure parameters of thin film growth process and nanowire arrays, the growth mechanism of nanowires was discussed. The degradation of dye Luo Dan B The photocatalytic properties of titanium acid tablets with different time after thermal oxidation test. The film structure characterization results show that certain vacuum conditions of titanium at 750 DEG C thermal oxidation after 5 ~ 10h large diameter 40~50 nm, length 3 ~ 5 m single crystal Jin Hongshi TiO_2 nanowires using H2O_2 titanium plate surface; to obtain a layer of porous amorphous TiO_2 thin layer, can significantly affect the growth of nanowires. The test results show that the photocatalytic performance, processing ability of flat sheet-like nanostructure Jin Hongshi film obtained by 1H vacuum thermal oxidation has the highest photocatalytic degradation of rhodamine B; heat treatment time extended from 5h to 10h, the photocatalytic properties of nanowires Jin Hongshi thin films were improved. The unit area TiO_2 effective loading problem on the titanium substrate layer by layer deposition / Jin Hongshi composite structure of anatase nanorods, sharp Titanium sol gel layer and rutile nano flowers, finally get a TiO_2 composite film has a "sandwich" structure. The composite film is divided into 79% general 21% anatase and rutile, close to the commercial P25 TiO_2; the band gap of 3 eV. UV light degradation of rhodamine B dye, first-order reaction the rate of composite film is 12.3 x 10-3 min-1, which was significantly higher than that of thin films of anatase / rutile nanorods (3.9 x 10-3 min-1), sol-gel anatase and rutile (0.3 * 10-3min-1) nanoflower (4.7 x 10-3 min-1) degradation rate. The results show that the proper combination of TiO_2 films with different phase composition and morphology of nano that is an effective way to improve the photocatalytic activity. In order to make full use of nanowires between nanowires in the film space, improve film TiO_2 loading, the nanowire array film immersed in The specific precursor solution, obtain a nano hierarchical structure of thin film. The thin film surface by uniform distribution of anatase TiO_2 nanowires and nano rutile TiO_2 main branch. The branch is single crystal structure, along with the prolonging of deposition time two times and gradually grew up. Because of the composite microstructure and its unique morphology, film with a specific band, phase structure, its high surface area, unique morphology branch and the effect of the mixed crystal makes the film light use efficiency effectively, electro-optical properties of organic matter degradation in aqueous solution and the photocatalytic performance can be improved significantly. In order to further clarify the role of heterogeneous nodes in the branch of TiO_2 nano structure in the film, the anatase TiO_2 nanowires films were placed in a certain concentration of TiCl4 TiF4 solution, the hierarchical structure of TiO_2 nanowires with different phases were prepared. Thin film. The thin film deposition TiCl4 solution obtained contained anatase / rutile phase structure of composite structure; and thin film deposition system of TiF4 solution obtained does not contain a heterogeneous structure. The preparation process by accurately controlling the system, in-depth analysis of thin film TiO_2 loading, the relationship between the phase composition and morphology and photocatalytic properties of nano the confirmation of the branch structure in the TiO_2 film "out of phase" knot "of an important role. In addition, also studied the anion doping effect of composite film on photocatalytic application in the presence of" natural aging "phenomenon, and the composite film with photocatalytic degradation properties.

【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：O643.36;TB383.2


本文編號：1531055