氧化铁薄膜的制备、掺杂及光解水性质研究
发布时间：2018-12-09 17:57
【摘要】：n型半导体材料氧化铁(α-Fe_2O_3)是光解水制氢领域的热点材料之一。它除了具有适宜的禁带宽度(~2.2 eV)外,还具有价格低廉、在水溶液中稳定性好等优点。同时α-Fe_2O_3的理论光电流高达12.6 mA/cm2,因此α-Fe_2O_3在光解水制氢领域极具研究价值。但在实际应用中,因为导电性差、空穴扩散距离短等缺点,α-Fe_2O_3的光解水性能远低于人们的预期。因此探索如何通过形貌控制、掺杂和表面修饰等方法对α-Fe_2O_3光电极进行优化进而提高其光解水性能,在当前能源和环境问题日益严峻的背景下具有重要的意义。本文通过数种方法在氟掺杂的二氧化锡(FTO)导电玻璃上制备了纳米结构的α-Fe_2O_3薄膜,同时对其光解水制氢性能进行了系统地研究,具体内容如下:1.使用水热法在FTO基底上生长前驱体,并通过热处理制备了α-Fe_2O_3纳米结构薄膜。通过调节添加剂的种类,实现了对α-Fe_2O_3微观结构形貌的控制,分别获得了短棱柱、纳米棒和多面体颗粒的α-Fe_2O_3纳米结构薄膜。其中短棱柱和纳米棒为沿[110]晶向垂直生长在FTO衬底上的单晶,而多面体则是由更小的各向同性的纳米颗粒堆积而成。以这些纳米结构薄膜为光阳极进行可见光驱动下的光解水研究表明,α-Fe_2O_3纳米棒薄膜的性能明显优于另外两种。XRD、SEM、电化学阻抗图谱分析表明α-Fe_2O_3纳米棒具有直径较小、多孔、垂直衬底并沿[110]晶向择优生长及施主浓度高的特点,这些特点使其光解水性能得到明显提高。2.通过简单、温和的方法在FTO衬底上制备了W-掺杂α-Fe_2O_3多孔短棱柱纳米结构薄膜。可见光驱动下的光解水实验证明,W-掺杂α-Fe_2O_3多孔短棱柱纳米结构电极具有明显高于α-Fe_2O_3的性质。例如,在1.60 V vs.RHE电位下,光电流密度达到1.1mA/cm2。同时,其光响应范围从紫外一直延伸到600 nm。稳定性实验表明,电极在0.1mol/L的NaOH电解液中长时间运行,其光电流几乎没有下降,表现了良好的稳定性。3.通过晶种法在FTO导电玻璃上制备了α-Fe_2O_3纳米结构薄膜。实验探究了热处理温度和晶种层厚度对α-Fe_2O_3光电极光解水性质的影响。线性伏安测试表明α-Fe_2O_3光电极的光解水性能与晶种层密切相关。晶种层经过500℃热处理处理的α-Fe_2O_3光电极的光解水性质最为优良。α-Fe_2O_3光电极的光电流在1.60 V vs.RHE处达到了0.63mA/cm2。
[Abstract]:N-type semiconductor ferric oxide (伪-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 伪-Fe_2O_3 is up to 12. 6 mA/cm2, so 伪-Fe_2O_3 is of great value in the field of hydrophotolysis to produce hydrogen. However, in practical application, the photolysis performance of 伪-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 伪-Fe_2O_3 photoelectrode by means of morphology control, doping and surface modification. Nanostructured 伪-Fe_2O_3 thin films were prepared on fluorine-doped tin dioxide (FTO) conductive glass by several methods. The photolysis properties of 伪-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 伪-Fe_2O_3 nanostructure thin films were prepared by heat treatment. The 伪-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 伪-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 伪-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 伪-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 伪-Fe_2O_3 nanorods obviously. 2. W- doped 伪-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 伪-Fe_2O_3 porous short prism nanostructure electrode has higher properties than 伪-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. 伪-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 伪-Fe_2O_3 were investigated. Linear voltammetry shows that the photolysis performance of 伪-Fe_2O_3 photoelectrode is closely related to the seed layer. The photolysis water properties of 伪-Fe_2O_3 photoelectrode treated at 500 鈩，
本文编号：2369799
[Abstract]:N-type semiconductor ferric oxide (伪-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 伪-Fe_2O_3 is up to 12. 6 mA/cm2, so 伪-Fe_2O_3 is of great value in the field of hydrophotolysis to produce hydrogen. However, in practical application, the photolysis performance of 伪-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 伪-Fe_2O_3 photoelectrode by means of morphology control, doping and surface modification. Nanostructured 伪-Fe_2O_3 thin films were prepared on fluorine-doped tin dioxide (FTO) conductive glass by several methods. The photolysis properties of 伪-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 伪-Fe_2O_3 nanostructure thin films were prepared by heat treatment. The 伪-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 伪-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 伪-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 伪-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 伪-Fe_2O_3 nanorods obviously. 2. W- doped 伪-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 伪-Fe_2O_3 porous short prism nanostructure electrode has higher properties than 伪-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. 伪-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 伪-Fe_2O_3 were investigated. Linear voltammetry shows that the photolysis performance of 伪-Fe_2O_3 photoelectrode is closely related to the seed layer. The photolysis water properties of 伪-Fe_2O_3 photoelectrode treated at 500 鈩，
本文编号：2369799
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