本文選題：AgBr + 空穴轉(zhuǎn)移��； 參考：《華東師范大學(xué)》2017年碩士論文

【摘要】：近年來(lái),環(huán)境污染、能源緊缺與社會(huì)發(fā)展和人類安居之間的矛盾日益嚴(yán)峻,環(huán)境修復(fù)和清潔能源的開發(fā)已成為全人類所面臨的亟待解決的難題。半導(dǎo)體光催化技術(shù)是最近幾十年興起的可以利用太陽(yáng)能實(shí)現(xiàn)對(duì)污染物的有效降解和產(chǎn)氫的技術(shù),因其操作簡(jiǎn)便、環(huán)境友好和應(yīng)用前景廣闊受到了越來(lái)越多的關(guān)注。溴化銀(AgBr)作為傳統(tǒng)的半導(dǎo)體材料,具有優(yōu)良的光敏性能,但在光照下很不穩(wěn)定,光腐蝕現(xiàn)象嚴(yán)重,阻礙了其在光催化方面的實(shí)際應(yīng)用。目前以AgBr為主體的復(fù)合光催化劑的研究主要集中于Ag/AgBr。然而,Ag/AgBr在光催化的過(guò)程中依舊受到較為嚴(yán)重的腐蝕。因而,AgBr基光催化劑的性能與穩(wěn)定性的研究對(duì)于AgBr基光催化劑的實(shí)際應(yīng)用具有重要的意義。本文通過(guò)緩慢分解Cu(OH)2生長(zhǎng)CuO,從而在AgBr微米顆粒表面修飾幾十納米的CuO顆粒。結(jié)果顯示CuO/AgBr樣品在光催化過(guò)程中反應(yīng)速率常數(shù)為純AgBr的4.3倍,對(duì)甲基橙(MO)的最終降解率達(dá)到91.2%,與純AgBr相比光催化性能得到了明顯的提高。光催化后溶液的pH值顯示CuO/AgBr樣品中光生空穴與Br-結(jié)合生成Br0的量明顯降低,光催化后的樣品沒有純AgBr明顯的分解再生長(zhǎng)現(xiàn)象,三次循環(huán)實(shí)驗(yàn)以后依舊保留了 85.1%的降解率,表明CuO/AgBr的光催化穩(wěn)定性得到了明顯的改善。進(jìn)一步的自由基檢測(cè)顯示空穴在CuO/AgBr體系中起主導(dǎo)作用,其機(jī)制來(lái)源于CuO與AgBr緊密接觸后在界面處形成p-n異質(zhì)結(jié),產(chǎn)生的內(nèi)建電場(chǎng)方向由n-AgBr指向p-CuO,從而AgBr中的光生空穴能夠轉(zhuǎn)移到CuO中。因此,CuO/AgBr復(fù)合光催化劑的性能與穩(wěn)定性的主要來(lái)源是空穴的轉(zhuǎn)移。在接下來(lái)的工作中我們通過(guò)液相超聲剝離塊狀MoS2至少數(shù)幾層,并包覆在KBr的表面,然后利用離子交換法和還原法合成了 MoS2/Ag/AgBr,成功制備了 MoS2平均厚度為4nm左右的復(fù)合光催化劑。樣品的相結(jié)構(gòu)與微觀形貌分別通過(guò)XRD和SEM進(jìn)行了表征,樣品中的MoS2以及層數(shù)通過(guò)激光拉曼光譜進(jìn)行測(cè)定,紫外-可見吸收光譜顯示MoS2/Ag/AgBr樣品對(duì)光的吸收能力明顯優(yōu)于Ag/AgBr,光催化性能評(píng)價(jià)顯示復(fù)合樣品的光催化活性提高了 50%左右。在進(jìn)一步的光催化機(jī)制探討中,我們發(fā)現(xiàn)超薄的MoS2夠轉(zhuǎn)移Ag/AgBr中的光生電子,從而改善了 Ag/AgBr的光催化性能。
[Abstract]:In recent years, the contradiction between environmental pollution, energy shortage, social development and human security has become increasingly severe. Environmental restoration and clean energy development have become a difficult problem to be solved urgently. Semiconductor photocatalytic technology is a technology that can effectively degrade pollutants and produce hydrogen by solar energy in recent decades. Due to its simple operation, environmental friendliness and wide application prospects, more and more attention has been paid to semiconductor photocatalytic technology. As a traditional semiconductor material, silver bromide (AgBrB) has excellent properties of Guang Min, but it is unstable in illumination and serious in photocorrosion, which hinders its practical application in photocatalysis. At present, the study of composite photocatalyst based on AgBr is mainly focused on Agr / AgBr. However, Agr / AgBr is still seriously corroded in the process of photocatalysis. Therefore, the study on the performance and stability of AgBr based photocatalysts is of great significance for the practical application of AgBr based photocatalysts. In this paper, dozens of nanometers of CuO particles were modified on the surface of AgBr micron particles by slow decomposition of Cu(OH)2. The results show that the reaction rate constant of CuO/AgBr sample is 4.3 times of that of pure AgBr, and the final degradation rate of methyl Orange MOA is 91.2. The photocatalytic performance of CuO/AgBr sample is obviously improved compared with pure AgBr. The pH value of the solution after photocatalysis showed that the amount of photogenerated holes combined with Br-to form Br0 in the CuO/AgBr sample was obviously decreased, and the photocatalytic sample did not undergo the decomposition and growth of pure AgBr, and the degradation rate of 85.1% was still retained after three cycles. The results show that the photocatalytic stability of CuO/AgBr is obviously improved. Further free radical detection showed that holes play a leading role in the CuO/AgBr system, and the mechanism originates from the formation of p-n heterojunction at the interface between CuO and AgBr after close contact. The direction of the generated built-in electric field is directed from n-AgBr to p-CuO, so that the photogenerated holes in AgBr can be transferred to CuO. Therefore, the main source of performance and stability of CuO / AgBr composite photocatalyst is hole transfer. In the following work, we used liquid phase ultrasound to peel off at least a few layers of bulk MoS2 and coated it on the surface of KBr. Then we synthesized MoS _ 2 / AgR _ (R) by ion exchange method and reduction method. The composite photocatalyst with average MoS2 thickness of about 4nm was successfully prepared. The phase structure and microstructure of the samples were characterized by XRD and SEM respectively. The MoS2 and the number of layers in the samples were measured by laser Raman spectroscopy. The UV-Vis absorption spectra showed that the photocatalytic activity of MoS2/Ag/AgBr samples was better than that of AgR / AgBr.The photocatalytic performance evaluation showed that the photocatalytic activity of the composite samples was increased by about 50%. In the further study of photocatalytic mechanism, we found that ultra-thin MoS2 can transfer photogenerated electrons in Ag/AgBr, thus improving the photocatalytic performance of Ag/AgBr.
【學(xué)位授予單位】：華東師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：O643.36

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 陳健鵬;李佐軍;;新世紀(jì)以來(lái)中國(guó)環(huán)境污染治理回顧與未來(lái)形勢(shì)展望[J];環(huán)境與可持續(xù)發(fā)展;2013年02期

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本文編號(hào)：1881240