本文關(guān)鍵詞： BiVO_4 薄膜 靜電誘導(dǎo) 自組裝 光電性能 光催化　出處：《陜西科技大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：鉍系氧化物由于其具有無毒,可見光響應(yīng),儲量豐富等優(yōu)勢而被認(rèn)為是一種在光催化領(lǐng)域有研究前景的光催化材料。目前對其的研究主要集中在粉體光催化劑上,而其在降解過程中存在著在水中易凝聚、失去活性、使光的穿透力受阻,難于分離和回收和不適用于連續(xù)流體體系等問題限制了其在光催化領(lǐng)域的廣泛應(yīng)用。而采用適當(dāng)?shù)姆椒▽€G系氧化物制備成薄膜便有望突破上述限制。為此本工作采用靜電誘導(dǎo)層層自組裝和旋涂法的方法合成鉍系氧化物薄膜,研究了其工藝對其形貌結(jié)構(gòu),光電性能,催化效果等的影響,探討B(tài)iVO_4薄膜的生成機(jī)理,研究薄膜的光電性能與光催化性能之間的聯(lián)系;揭示其內(nèi)部電荷運(yùn)動規(guī)律以及催化機(jī)理。主要研究內(nèi)容如下:(1)用靜電誘導(dǎo)層層自組裝的方法制備單斜相BiVO_4薄膜。前驅(qū)液濃度為0.01 mol/L,晶化溫度為500 oC時制備的單斜相BiVO_4薄膜具有較高的光生電子-空穴分離率和電荷轉(zhuǎn)移效率,可見光下照射180 min后對羅丹明B降解率為26%。反應(yīng)初期,功能化的基板誘導(dǎo)吸附[Bi(NO_3)_3VO_2]~+膠粒,形成[Bi(NO_3)_3VO_2]-O-FTO前驅(qū)薄膜層,前驅(qū)液中酸性的逐漸減弱,溶液中形成電中性的BiOVO_3膠核,被基板上[Bi(NO_3)_3VO_2]層誘導(dǎo)吸附,形成(BiOVO_3)[Bi(NO_3)_3VO_2]層,隨著時間的增加溶液的zeta電位逐漸增加,形成[(BiOVO_3)NO_3]~-膠粒,被基板上(BiOVO_3)[Bi(NO_3)_3VO_2]層誘導(dǎo)吸附,形成[(BiOVO_3)NO_3](BiOVO_3)[Bi(NO_3)_3VO_2]層,隨著時間的增加,前驅(qū)液中NH~(3+),被進(jìn)一步吸附,形成NH_3[(BiOVO_3)NO_3](BiOVO_3)[Bi(NO_3)_3VO_2]層,晶化處理后形成BiVO_4薄膜。(2)用靜電誘導(dǎo)層層自組裝的方法制備出BiVO_4/Ti O_2復(fù)合薄膜。復(fù)合薄膜中BiVO_4與TiO_2之間形成了類p-n結(jié)的界面結(jié)構(gòu),電子從BiVO_4向TiO_2方向傳遞、空穴從TiO_2向BiVO_4方向傳遞。光照瞬間復(fù)合薄膜沒有出現(xiàn)明顯的陽極尖峰表面電子復(fù)合率降低。復(fù)合薄膜與單一薄膜相比擁有高的氧化能力和載流子濃度。(3)用旋涂法制備CeO_2/Ce_xBi_(2-x)WO_6電極薄膜,發(fā)現(xiàn)CeO_2/Ce_xBi_(2-x)WO_6異質(zhì)結(jié)形成的負(fù)光電流現(xiàn)象與光催化過程中空穴和超氧自由基為活性物種有關(guān),異質(zhì)結(jié)結(jié)構(gòu)的存在增加了光生電子-空穴分離率以及減少了電荷轉(zhuǎn)移時間。CeO_2/Ce_xBi_(2-x)WO_6光催化效果改善的因素主要是由于異質(zhì)結(jié)結(jié)構(gòu)光生促進(jìn)電荷和Ce~(3+)的取代導(dǎo)致光生電子-空穴的復(fù)合過程的延緩。(4)微波溶劑熱中乙醇和Er~(3+)能抑制Bi_2WO_6的形成。煅燒后形成高結(jié)晶性的Er~(3+)摻雜Bi_(2-x)Er_xWO_6晶體,用旋涂法制備將Bi_(2-x)Er_xWO_6光電極。Er~(3+)摻雜使Bi_(2-x)Er_xWO_6電極表面光電子復(fù)合率增加為70.93%和表面光電流增加,具有較高的氧化能力和可移動電子。電極的電荷轉(zhuǎn)移電阻從1415 kΩ減到826.1 kΩ,表明電子-空穴分離率較強(qiáng)。電極在波長為542 nm和654 nm處出現(xiàn)光電轉(zhuǎn)換特征峰。其光電流較大的原因主要是由于Er~(3+)摻雜引入了大量缺陷和Er~(3+)所帶來的上轉(zhuǎn)化效應(yīng)引起的。
[Abstract]:Bismuth oxide is considered to be a promising photocatalyst in the field of photocatalysis due to its advantages of nontoxic, visible light response and abundant reserves. At present, the research on bismuth oxides is mainly focused on powder photocatalysts. In the process of degradation, it is easy to agglomerate in water and lose its activity, which hinders the penetration of light. It is difficult to separate and recover and is not suitable for continuous fluid systems, which limits its wide application in photocatalysis. However, it is expected to break the above limit by using appropriate methods to prepare bismuth oxide thin films. Bismuth oxide thin films were synthesized by electrostatic induced layer-by-layer self-assembly and spin-coating. The effects of the process on the morphology, photoelectricity and catalytic performance of BiVO_4 films were studied. The formation mechanism of BiVO_4 films and the relationship between the photocatalytic properties and the optoelectronic properties of the films were studied. The main research contents are as follows: (1) monoclinic BiVO_4 thin films were prepared by electrostatic induction layer by layer self-assembly. The monoclinic BiVO_4 films were prepared at the precursor concentration of 0.01 mol / L and the crystallization temperature of 500oC. Phase BiVO_4 thin films have high photoelectron hole separation rate and charge transfer efficiency. The degradation rate of rhodamine B under visible light irradiation for 180 min was 26.5%. At the beginning of the reaction, the functional substrate induced adsorption of [Bi(NO_3)_3VO_2] ~ colloid particles to form [Bi(NO_3)_3VO_2] -O-FTO precursor film layer. The acidity of the precursor solution gradually weakened, and an electrically neutral BiOVO_3 gel nucleus was formed in the solution. The [Bi(NO_3)_3VO_2] layer was induced to adsorb on the substrate to form a [Bi(NO_3)_3VO_2] layer. With the increase of time, the zeta potential of the solution gradually increased, resulting in the formation of [BiOVO3HNO3]-Bi(NO_3)_3VO_2 particles, which were induced to be adsorbed by the BiOVO3] [Bi(NO_3)_3VO_2] layer on the substrate, forming a [BiOVO3No3] BiOVO3] [Bi(NO_3)_3VO_2] layer. With the increase of time, NH~(3 in the precursor solution was further adsorbed. The formation of NH_3 [BiOVO3No3] BiOV _ 3] [Bi(NO_3)_3VO_2] layer, after crystallization, the formation of BiVO_4 thin films. (2) BiVO_4/Ti O _ 2 composite films were prepared by layer by layer self-assembly method induced by static electricity. The interface structure between BiVO_4 and TiO_2 was formed, and electrons were transferred from BiVO_4 to TiO_2. Hole transfer from TiO_2 to BiVO_4. There is no obvious decrease of electron recombination rate on anodic peak surface of the composite film. The composite film has higher oxidation ability and carrier concentration than single film. Preparation of CeO_2/Ce_xBi_(2-x)WO_6 electrode films, It was found that the negative photocurrent in the formation of CeO_2/Ce_xBi_(2-x)WO_6 heterostructures was related to the existence of holes and superoxide radicals as active species during photocatalysis. The existence of heterojunction structure increases the photoelectron hole separation rate and reduces the charge transfer time. Ceo\%\%\%\% Cex\\%\%\%\%\%\%\%\%\%\%\%\%\\%\\%\\\%\\\. The delay in the process of electron-hole recombination. (4) ethanol and Er~(3 in microwave solvothermal can inhibit the formation of Bi_2WO_6. After calcination, a highly crystallized Er~(3) doped Bi_(2-x)Er_xWO_6 crystal is formed. The photoelectron recombination rate on the surface of Bi_(2-x)Er_xWO_6 electrode was increased to 70.93% and the photocurrent on the surface was increased by doping Bi_(2-x)Er_xWO_6 photoelectrode. The charge transfer resistance of the electrode was reduced from 1415 k 惟 to 826.1 k 惟, indicating that the electron-hole separation rate was strong. The photoelectricity conversion peak appeared at the wavelength of 542 nm and 654 nm. The reason for the large flow is mainly due to the introduction of a large number of defects in Er~(3 doping and the upconversion effect brought about by Er~(3).
【學(xué)位授予單位】：陜西科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB383.2

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