氧化鐵薄膜的制備、摻雜及光解水性質(zhì)研究
發(fā)布時(shí)間：2018-12-09 17:57
【摘要】：n型半導(dǎo)體材料氧化鐵(α-Fe_2O_3)是光解水制氫領(lǐng)域的熱點(diǎn)材料之一。它除了具有適宜的禁帶寬度(~2.2 eV)外,還具有價(jià)格低廉、在水溶液中穩(wěn)定性好等優(yōu)點(diǎn)。同時(shí)α-Fe_2O_3的理論光電流高達(dá)12.6 mA/cm2,因此α-Fe_2O_3在光解水制氫領(lǐng)域極具研究?jī)r(jià)值。但在實(shí)際應(yīng)用中,因?yàn)閷?dǎo)電性差、空穴擴(kuò)散距離短等缺點(diǎn),α-Fe_2O_3的光解水性能遠(yuǎn)低于人們的預(yù)期。因此探索如何通過(guò)形貌控制、摻雜和表面修飾等方法對(duì)α-Fe_2O_3光電極進(jìn)行優(yōu)化進(jìn)而提高其光解水性能,在當(dāng)前能源和環(huán)境問(wèn)題日益嚴(yán)峻的背景下具有重要的意義。本文通過(guò)數(shù)種方法在氟摻雜的二氧化錫(FTO)導(dǎo)電玻璃上制備了納米結(jié)構(gòu)的α-Fe_2O_3薄膜,同時(shí)對(duì)其光解水制氫性能進(jìn)行了系統(tǒng)地研究,具體內(nèi)容如下:1.使用水熱法在FTO基底上生長(zhǎng)前驅(qū)體,并通過(guò)熱處理制備了α-Fe_2O_3納米結(jié)構(gòu)薄膜。通過(guò)調(diào)節(jié)添加劑的種類,實(shí)現(xiàn)了對(duì)α-Fe_2O_3微觀結(jié)構(gòu)形貌的控制,分別獲得了短棱柱、納米棒和多面體顆粒的α-Fe_2O_3納米結(jié)構(gòu)薄膜。其中短棱柱和納米棒為沿[110]晶向垂直生長(zhǎng)在FTO襯底上的單晶,而多面體則是由更小的各向同性的納米顆粒堆積而成。以這些納米結(jié)構(gòu)薄膜為光陽(yáng)極進(jìn)行可見(jiàn)光驅(qū)動(dòng)下的光解水研究表明,α-Fe_2O_3納米棒薄膜的性能明顯優(yōu)于另外兩種。XRD、SEM、電化學(xué)阻抗圖譜分析表明α-Fe_2O_3納米棒具有直徑較小、多孔、垂直襯底并沿[110]晶向擇優(yōu)生長(zhǎng)及施主濃度高的特點(diǎn),這些特點(diǎn)使其光解水性能得到明顯提高。2.通過(guò)簡(jiǎn)單、溫和的方法在FTO襯底上制備了W-摻雜α-Fe_2O_3多孔短棱柱納米結(jié)構(gòu)薄膜。可見(jiàn)光驅(qū)動(dòng)下的光解水實(shí)驗(yàn)證明,W-摻雜α-Fe_2O_3多孔短棱柱納米結(jié)構(gòu)電極具有明顯高于α-Fe_2O_3的性質(zhì)。例如,在1.60 V vs.RHE電位下,光電流密度達(dá)到1.1mA/cm2。同時(shí),其光響應(yīng)范圍從紫外一直延伸到600 nm。穩(wěn)定性實(shí)驗(yàn)表明,電極在0.1mol/L的NaOH電解液中長(zhǎng)時(shí)間運(yùn)行,其光電流幾乎沒(méi)有下降,表現(xiàn)了良好的穩(wěn)定性。3.通過(guò)晶種法在FTO導(dǎo)電玻璃上制備了α-Fe_2O_3納米結(jié)構(gòu)薄膜。實(shí)驗(yàn)探究了熱處理溫度和晶種層厚度對(duì)α-Fe_2O_3光電極光解水性質(zhì)的影響。線性伏安測(cè)試表明α-Fe_2O_3光電極的光解水性能與晶種層密切相關(guān)。晶種層經(jīng)過(guò)500℃熱處理處理的α-Fe_2O_3光電極的光解水性質(zhì)最為優(yōu)良。α-Fe_2O_3光電極的光電流在1.60 V vs.RHE處達(dá)到了0.63mA/cm2。
[Abstract]:N-type semiconductor ferric oxide (偽-Fe_2O_3) is one of the hot materials in the field of hydrogen production by photolysis. In addition to the suitable bandgap (~ 2.2 eV), it also has the advantages of low price and good stability in aqueous solution. At the same time, the theoretical photocurrent of 偽-Fe_2O_3 is up to 12. 6 mA/cm2, so 偽-Fe_2O_3 is of great value in the field of hydrophotolysis to produce hydrogen. However, in practical application, the photolysis performance of 偽-Fe_2O_3 is much lower than expected due to its poor conductivity and short hole diffusion distance. Therefore, it is of great significance to explore how to optimize the photolysis performance of 偽-Fe_2O_3 photoelectrode by means of morphology control, doping and surface modification. Nanostructured 偽-Fe_2O_3 thin films were prepared on fluorine-doped tin dioxide (FTO) conductive glass by several methods. The photolysis properties of 偽-Fe_2O_3 films were studied systematically. The main contents are as follows: 1. The precursor was grown on FTO substrate by hydrothermal method and 偽-Fe_2O_3 nanostructure thin films were prepared by heat treatment. The 偽-Fe_2O_3 nanostructure films with short prism, nanorods and polyhedron particles were obtained by adjusting the kinds of additives to control the microstructure and morphology of 偽-Fe_2O_3. The short prism and nanorods are single crystals grown perpendicularly on FTO substrates along the [110] crystal direction, while the polyhedrons are formed by stacking smaller isotropic nanoparticles. Using these nanocrystalline thin films as photoanode, the photolysis of water driven by visible light shows that the properties of 偽-Fe_2O_3 nanorod films are obviously superior to those of the other two kinds of films. XRD,SEM,. The electrochemical impedance spectrum analysis shows that 偽-Fe_2O_3 nanorods have the characteristics of small diameter, porous, perpendicular substrate and high donor concentration along the [11010] crystal direction. These characteristics improve the photodegradation properties of 偽-Fe_2O_3 nanorods obviously. 2. W- doped 偽-Fe_2O_3 porous short prism nanocrystalline films were prepared on FTO substrates by a simple and mild method. Visible light-driven photolysis experiments show that W- doped 偽-Fe_2O_3 porous short prism nanostructure electrode has higher properties than 偽-Fe_2O_3. For example, at 1.60 V vs.RHE potential, the photocurrent density is 1.1 Ma / cm ~ 2. At the same time, the optical response range extends from UV to 600 nm.. The stability experiment shows that the photocurrent of the electrode in NaOH electrolyte of 0.1mol/L for a long time has almost no decrease, showing good stability. 偽-Fe_2O_3 nanocrystalline films were prepared on FTO conductive glass by seed method. The effects of heat treatment temperature and seed layer thickness on the photoluminescence properties of 偽-Fe_2O_3 were investigated. Linear voltammetry shows that the photolysis performance of 偽-Fe_2O_3 photoelectrode is closely related to the seed layer. The photolysis water properties of 偽-Fe_2O_3 photoelectrode treated at 500 鈩，
本文編號(hào)：2369799
[Abstract]:N-type semiconductor ferric oxide (偽-Fe_2O_3) is one of the hot materials in the field of hydrogen production by photolysis. In addition to the suitable bandgap (~ 2.2 eV), it also has the advantages of low price and good stability in aqueous solution. At the same time, the theoretical photocurrent of 偽-Fe_2O_3 is up to 12. 6 mA/cm2, so 偽-Fe_2O_3 is of great value in the field of hydrophotolysis to produce hydrogen. However, in practical application, the photolysis performance of 偽-Fe_2O_3 is much lower than expected due to its poor conductivity and short hole diffusion distance. Therefore, it is of great significance to explore how to optimize the photolysis performance of 偽-Fe_2O_3 photoelectrode by means of morphology control, doping and surface modification. Nanostructured 偽-Fe_2O_3 thin films were prepared on fluorine-doped tin dioxide (FTO) conductive glass by several methods. The photolysis properties of 偽-Fe_2O_3 films were studied systematically. The main contents are as follows: 1. The precursor was grown on FTO substrate by hydrothermal method and 偽-Fe_2O_3 nanostructure thin films were prepared by heat treatment. The 偽-Fe_2O_3 nanostructure films with short prism, nanorods and polyhedron particles were obtained by adjusting the kinds of additives to control the microstructure and morphology of 偽-Fe_2O_3. The short prism and nanorods are single crystals grown perpendicularly on FTO substrates along the [110] crystal direction, while the polyhedrons are formed by stacking smaller isotropic nanoparticles. Using these nanocrystalline thin films as photoanode, the photolysis of water driven by visible light shows that the properties of 偽-Fe_2O_3 nanorod films are obviously superior to those of the other two kinds of films. XRD,SEM,. The electrochemical impedance spectrum analysis shows that 偽-Fe_2O_3 nanorods have the characteristics of small diameter, porous, perpendicular substrate and high donor concentration along the [11010] crystal direction. These characteristics improve the photodegradation properties of 偽-Fe_2O_3 nanorods obviously. 2. W- doped 偽-Fe_2O_3 porous short prism nanocrystalline films were prepared on FTO substrates by a simple and mild method. Visible light-driven photolysis experiments show that W- doped 偽-Fe_2O_3 porous short prism nanostructure electrode has higher properties than 偽-Fe_2O_3. For example, at 1.60 V vs.RHE potential, the photocurrent density is 1.1 Ma / cm ~ 2. At the same time, the optical response range extends from UV to 600 nm.. The stability experiment shows that the photocurrent of the electrode in NaOH electrolyte of 0.1mol/L for a long time has almost no decrease, showing good stability. 偽-Fe_2O_3 nanocrystalline films were prepared on FTO conductive glass by seed method. The effects of heat treatment temperature and seed layer thickness on the photoluminescence properties of 偽-Fe_2O_3 were investigated. Linear voltammetry shows that the photolysis performance of 偽-Fe_2O_3 photoelectrode is closely related to the seed layer. The photolysis water properties of 偽-Fe_2O_3 photoelectrode treated at 500 鈩，
本文編號(hào)：2369799
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