【摘要】：光電化學(xué)水分解是將太陽(yáng)能轉(zhuǎn)換成無(wú)污染的化學(xué)燃料來(lái)解決能源匱乏及環(huán)境污染的一條嶄新途徑。提高光陽(yáng)極光生電荷的傳輸和轉(zhuǎn)移能力是該領(lǐng)域研究的核心問(wèn)題。本文以Fe_2O_3為光陽(yáng)極,利用其較寬的光譜響應(yīng)、合理的價(jià)帶位置以及良好的化學(xué)穩(wěn)定性等特點(diǎn),重點(diǎn)研究高溫快速退火提升Fe_2O_3光電化學(xué)水分解性能的作用機(jī)制,并協(xié)同界面修飾,進(jìn)一步提高光生電子和空穴分離效率,探索提高Fe_2O_3光陽(yáng)極光電化學(xué)性能的有效途徑。具體研究工作如下:針對(duì)Fe_2O_3薄膜結(jié)晶性差,體內(nèi)復(fù)合嚴(yán)重的問(wèn)題,分別對(duì)FTO/Fe_2O_3光陽(yáng)極進(jìn)行時(shí)間相對(duì)較長(zhǎng)的傳統(tǒng)退火以及快速升溫的高溫退火。研究發(fā)現(xiàn),高溫快速退火能夠提高氧化鐵結(jié)晶性并去除部分表面態(tài),從而提高體內(nèi)電荷傳輸和Fe_2O_3/電解液界面電荷轉(zhuǎn)移能力,增加電荷分離效率。且高溫快速退火相對(duì)傳統(tǒng)的高溫退火,對(duì)FTO襯底的導(dǎo)電性破壞小,能夠保持對(duì)電子良好的收集能力,因此FTO/Fe_2O_3光陽(yáng)極展示了優(yōu)異的光電化學(xué)水分解性能。針對(duì)FTO/Fe_2O_3界面處的電荷復(fù)合問(wèn)題,采用層層沉積的方法在FTO/Fe_2O_3界面引入超薄的高結(jié)晶性的鈦酸片層(Ti O_2NS),通過(guò)界面修飾抑制電子從FTO向Fe_2O_3反向流動(dòng)引起的復(fù)合,提高光生電荷分離。接著對(duì)FTO/TiO_2/Fe_2O_3光陽(yáng)極進(jìn)行高溫快速退火處理。研究表明,高溫條件下,TiO_2NS不僅能夠抑制部分電子反向流動(dòng)引起的復(fù)合,而且界面處的Ti存在向Fe_2O_3中擴(kuò)散的現(xiàn)象。Ti4+擴(kuò)散到Fe_2O_3中作為施主雜質(zhì),提高載流子濃度,增大帶彎,促進(jìn)光生電子和空穴的分離。同時(shí),高溫快速退火能夠提高Fe_2O_3結(jié)晶性,加快電荷傳輸,增加界面電荷轉(zhuǎn)移能力,協(xié)同提高FTO/TiO_2/Fe_2O_3光陽(yáng)極的光電流密度。綜上所述,高溫快速退火能夠同時(shí)降低Fe_2O_3體內(nèi)和表面電荷復(fù)合,且能實(shí)現(xiàn)向Fe_2O_3中的有效元素?fù)诫s。該方法簡(jiǎn)單、易操作,可以嘗試應(yīng)用其它電極,或進(jìn)行其它元素?fù)诫s,在優(yōu)化光電化學(xué)水分解光陽(yáng)極材料的發(fā)展中具有重要意義。
[Abstract]:Photoelectrochemical water decomposition is a new way to solve energy shortage and environmental pollution by converting solar energy into non-polluting chemical fuel. Improving the transmission and transfer ability of auroral charge is the key problem in this field. In this paper, with Fe_2O_3 as the photoanode, the mechanism of improving the photo-chemical water decomposition of Fe_2O_3 by high temperature rapid annealing is studied, which is based on its wide spectral response, reasonable valence band position and good chemical stability. The efficiency of photoelectron and hole separation was further improved by synergistic interfacial modification, and an effective way to improve the photoelectrochemical properties of Fe_2O_3 photoanode was explored. The specific research work is as follows: aiming at the problems of poor crystallinity and in vivo compounding of Fe_2O_3 thin films, the traditional annealing of FTO/Fe_2O_3 photoanode and the high temperature annealing of FTO/Fe_2O_3 photoanode are carried out respectively. It is found that high temperature rapid annealing can improve the crystallinity of iron oxide and remove part of the surface state, thus improving the charge transport in vivo and the charge transfer ability at the interface of Fe_2O_3/ electrolyte, and increasing the efficiency of charge separation. Compared with the traditional high temperature annealing, the high temperature rapid annealing has little damage to the electrical conductivity of the FTO substrate, and can keep good collection ability of electrons. Therefore, the FTO/Fe_2O_3 photoanode exhibits excellent photochemical water decomposition performance. Aiming at the problem of charge recombination at the interface of FTO/Fe_2O_3, layer by layer deposition method was used to introduce ultra-thin and highly crystallized titanate lamellar (Ti O_2NS) at the interface of FTO/Fe_2O_3. The interfacial modification inhibits the recombination of electrons from FTO to Fe_2O_3 and increases the photogenic charge separation. Then the FTO/TiO_2/Fe_2O_3 photoanode was treated by high temperature rapid annealing. The results show that at high temperature, TiO_2NS can not only inhibit the recombination caused by partial reverse electron flow, but also the Ti at the interface diffuses into Fe_2O_3. Ti4 diffuses into Fe_2O_3 as donor impurity. Increasing carrier concentration, increasing band bending, and promoting the separation of photogenerated electrons and holes. At the same time, the high temperature rapid annealing can improve the crystallization of Fe_2O_3, accelerate the charge transfer, increase the interface charge transfer ability, and increase the photocurrent density of the FTO/TiO_2/Fe_2O_3 photoanode. In conclusion, high temperature rapid annealing can simultaneously reduce the internal and surface charge recombination of Fe_2O_3, and can achieve effective element doping in Fe_2O_3. The method is simple and easy to operate. It can be applied to other electrodes or doped with other elements. It is of great significance in the development of optoelectronic chemical water decomposition photoanode materials.
【學(xué)位授予單位】：東北師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TQ116.21

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本文編號(hào)：2304433