二氧化鈦可控晶面制備光催化劑的理論及實驗研究
發(fā)布時間：2018-08-05 09:25
【摘要】：近年來,二氧化鈦(TiO_2)以其成本低廉、無二次污染、極強氧化還原能力、耐光學和化學腐蝕性及性質(zhì)穩(wěn)定,成為整個半導體光催化研究領(lǐng)域的熱點。盡管,TiO_2在光催化研究領(lǐng)域已取得了較多理論和實驗研究成果,但TiO_2光催化方法依然未能取得大規(guī)模應用,制約其應用主要瓶頸在于:①TiO_2光催化量子效率不夠高;②TiO_2對可見光的利用率低,需要外加能耗。目前傳統(tǒng)合成方法對銳鈦礦TiO_2晶面的暴露比例和生長趨勢可控性不強,同時,生成的晶體排布無序,粒徑大小不一,隨機性大,不能充分利用TiO_2(001)晶面的光催化性能。原因在于TiO_2各個晶面暴露的選擇性生長機理尚不清楚。外加,傳統(tǒng)合成工藝自身參數(shù)的不可控性,以至于對TiO_2晶面的暴露比例及生長趨勢得不到充分的控制,也就限制了 TiO_2光催化性能的最優(yōu)化利用。因此,探明TiO_2晶面生長機理,探索可控、可調(diào)的晶面暴露的制備技術(shù)與方法,對于提高TiO_2光催化性能有較大的研究意義。本文首先采用理論計算對TiO_2光催化面進行理論研究,通過表面能、吸附能、態(tài)密度和能帶等數(shù)據(jù)獲得Tio2晶面生長的理論機理;再結(jié)合實驗,采用原子層沉積技術(shù)制備TiO_2光催化劑,并通過控制反應前驅(qū)體脈沖的循環(huán)周期數(shù)和溫度來控制TiO_2成膜結(jié)構(gòu)和形貌;利用XRD、SEM、TEM對TiO_2薄膜進行表征,以期獲得制備可控、高效的光降解催化劑的機理。通過理論計算發(fā)現(xiàn):在TiO_2(001)、(010)和(101)三個晶面中,(001)晶面表面能為1.09 J/m2具有最好的光催化活性;再以鈦酸鋇(BTO)晶體作為基底,構(gòu)建TiO_2-BTO生長模型,誘導TiO_2不同晶面生長,(001)晶面以結(jié)合能為-1.27eV,鍵長分別為1.916A和1.932A,成為生長最為穩(wěn)定的模型。同時發(fā)現(xiàn)TiO_2(001)晶面不同層數(shù)的生長對催化降解有一定影響利用原子層沉積方法制備TiO_2光催化劑,通過對設(shè)備參數(shù)的不斷調(diào)試得出最佳參數(shù),并在以鈦酸鋇為基體的石英玻璃片上鍍TiO_2薄膜,制備TiO_2光催化劑。采用XRD、SEM、TEM對制備的樣品進行表征分析,結(jié)果證明利用原子層沉積技術(shù)成功的將TiO_2以膜的形式鍍在基體表面,鍍膜厚度隨沉積圈數(shù)的增加而增加。將制備的TiO_2光催化劑,對一定濃度的甲基橙進行光催化降解實驗,結(jié)果證明利用ALD技術(shù)制備的TiO_2光催化劑,能夠?qū)τ袡C物污染物進行更好的催化降解。
[Abstract]:In recent years, titanium dioxide (TiO_2) has become a hotspot in the field of semiconductor photocatalysis because of its low cost, no secondary pollution, strong redox ability, optical and chemical corrosion resistance and stable properties. Although TiO2 has made many theoretical and experimental achievements in the field of photocatalytic research, the TiO_2 photocatalytic method has not been applied on a large scale, and the main bottleneck of its application is that the quantum efficiency of photocatalysis is not high enough. The utilization rate of visible light by 2TiO_2 is low, which requires additional energy consumption. At present, the exposure ratio and growth trend of anatase TiO_2 crystal surface are not controlled by traditional synthesis methods. At the same time, the resulting crystals are disordered, with different particle size and large randomness, which can not make full use of the photocatalytic performance of TiO_2 (001) crystal plane. The reason is that the selective growth mechanism of TiO_2 exposed to various crystal faces is not clear. In addition, the uncontrollability of the parameters of the traditional synthesis process makes it impossible to control the exposure ratio and growth trend of the TiO_2 crystal plane, which limits the optimum utilization of the photocatalytic properties of TiO_2. Therefore, it is of great significance to investigate the growth mechanism of TiO_2 crystal plane and to explore the preparation techniques and methods of controllable and adjustable exposure of crystal plane for improving the photocatalytic performance of TiO_2. In this paper, the theoretical mechanism of the growth of TiO_2 photocatalytic surface is obtained by using the data of surface energy, adsorption energy, density of state and energy band. TiO_2 photocatalyst was prepared by atomic layer deposition technique, and the structure and morphology of TiO_2 film were controlled by controlling the cycle period and temperature of the reaction precursor pulse, and the structure and morphology of TiO_2 film were characterized by XRDX SEMTEM in order to obtain controllable preparation of TiO_2 film. Mechanism of highly efficient photodegradation catalysts. The theoretical calculation shows that the surface energy of (001) crystal surface is 1.09 J/m2 with the best photocatalytic activity in the TiO_2 (001), (010) and (101) faces, and the TiO_2-BTO growth model is constructed by using barium titanate (BTO) crystal as the substrate. (001) the binding energy of (001) faces is -1.27 EV, and the bond lengths are 1.916A and 1.932A, respectively, which are the most stable growth models. At the same time, it was found that the growth of different layers of TiO_2 (001) crystal plane had a certain influence on the catalytic degradation. The TiO_2 photocatalyst was prepared by atomic layer deposition, and the optimum parameters were obtained by adjusting the parameters of the equipment. TiO_2 films were deposited on quartz glass substrates of barium titanate to prepare TiO_2 photocatalyst. The TiO_2 was successfully deposited on the substrate by atomic layer deposition, and the thickness of the film increased with the increase of the number of coils. The photocatalytic degradation experiments of methyl orange with certain concentration of TiO_2 photocatalyst were carried out. The results showed that the TiO_2 photocatalyst prepared by ALD technology could better catalyze the degradation of organic pollutants.
【學位授予單位】：重慶三峽學院
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O643.36
本文編號：2165359
[Abstract]:In recent years, titanium dioxide (TiO_2) has become a hotspot in the field of semiconductor photocatalysis because of its low cost, no secondary pollution, strong redox ability, optical and chemical corrosion resistance and stable properties. Although TiO2 has made many theoretical and experimental achievements in the field of photocatalytic research, the TiO_2 photocatalytic method has not been applied on a large scale, and the main bottleneck of its application is that the quantum efficiency of photocatalysis is not high enough. The utilization rate of visible light by 2TiO_2 is low, which requires additional energy consumption. At present, the exposure ratio and growth trend of anatase TiO_2 crystal surface are not controlled by traditional synthesis methods. At the same time, the resulting crystals are disordered, with different particle size and large randomness, which can not make full use of the photocatalytic performance of TiO_2 (001) crystal plane. The reason is that the selective growth mechanism of TiO_2 exposed to various crystal faces is not clear. In addition, the uncontrollability of the parameters of the traditional synthesis process makes it impossible to control the exposure ratio and growth trend of the TiO_2 crystal plane, which limits the optimum utilization of the photocatalytic properties of TiO_2. Therefore, it is of great significance to investigate the growth mechanism of TiO_2 crystal plane and to explore the preparation techniques and methods of controllable and adjustable exposure of crystal plane for improving the photocatalytic performance of TiO_2. In this paper, the theoretical mechanism of the growth of TiO_2 photocatalytic surface is obtained by using the data of surface energy, adsorption energy, density of state and energy band. TiO_2 photocatalyst was prepared by atomic layer deposition technique, and the structure and morphology of TiO_2 film were controlled by controlling the cycle period and temperature of the reaction precursor pulse, and the structure and morphology of TiO_2 film were characterized by XRDX SEMTEM in order to obtain controllable preparation of TiO_2 film. Mechanism of highly efficient photodegradation catalysts. The theoretical calculation shows that the surface energy of (001) crystal surface is 1.09 J/m2 with the best photocatalytic activity in the TiO_2 (001), (010) and (101) faces, and the TiO_2-BTO growth model is constructed by using barium titanate (BTO) crystal as the substrate. (001) the binding energy of (001) faces is -1.27 EV, and the bond lengths are 1.916A and 1.932A, respectively, which are the most stable growth models. At the same time, it was found that the growth of different layers of TiO_2 (001) crystal plane had a certain influence on the catalytic degradation. The TiO_2 photocatalyst was prepared by atomic layer deposition, and the optimum parameters were obtained by adjusting the parameters of the equipment. TiO_2 films were deposited on quartz glass substrates of barium titanate to prepare TiO_2 photocatalyst. The TiO_2 was successfully deposited on the substrate by atomic layer deposition, and the thickness of the film increased with the increase of the number of coils. The photocatalytic degradation experiments of methyl orange with certain concentration of TiO_2 photocatalyst were carried out. The results showed that the TiO_2 photocatalyst prepared by ALD technology could better catalyze the degradation of organic pollutants.
【學位授予單位】：重慶三峽學院
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O643.36
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