氮改性宽带隙氧化物纳米材料的合成及其光催化应用

发布时间：2018-05-22 12:55

本文选题：二氧化锡 + 二氧化铈　；参考：《扬州大学》2015年硕士论文

【摘要】：半导体光催化还原技术是一种很有发展前途的处理Cr(VI)废水的方法,而研发高效、稳定、经济、无毒的可见光催化剂是实现其工业化应用的关键。虽然SnO2、CeO2和Zr02作为光催化剂材料具有稳定、低成本、无毒的优点,但它们都是宽带隙半导体材料(Sn02、Ce02和Zr02的带隙值分别为3.8、3.2和5.0 eV),主要吸收太阳光中的紫外光(紫外光只约占太阳光能量的5%),极大地影响了这些光催化剂的光催化活性,限制了它们在光催化领域中的实际应用。因此,通过对SnO2、CeO2和Zr02这些宽带隙半导体材料进行改性,拓宽其光响应范围,从而提高它们的可见光催化活性,是发展新型高效可见光催化剂的重要手段之一。本文主要研究了N改性SnO2、CeO2和Zr02纳米晶的溶剂热合成及其光催化处理水中Cr(VI)的应用。已经完成的主要研究内容总结如下：1.以SnCl4-5H2O、不同用量的HN03和无水乙醇为原料,采用溶剂热法,在180。C加热12 h合成了一系列四方相N掺杂Sn02纳米材料(如SnO2-HNO3-1、SnO2-HNO3-2和SnO2-HNO3-3)。利用x-射线衍射(XRD)、透射电子显微镜(TEM)、X-射线光电子能谱(XPS)、傅里叶变换红外光谱仪(FT-IR)和紫外-可见漫反射光谱(UV-vis)等测试手段表征了所得产物的组成、结构和光学性质。以可见光(λ420 nm)为光源、以K2Cr2O7水溶液为模型污染物,考察了不同硝酸用量情况下所合成的N掺杂Sn02纳米材料的光催化活性,并与SnO2-NH3(指用氨水代替硝酸,溶剂热合成的Sn02纳米晶)的光催化活性做了对比。结果表明：(1)在可见光(λ420 nm)照射下,SnO2-HNO3-1, SnO2-HNO3-2和SnO2-HNO3-3对Cr(VI)的还原表现出很高的可见光催化活性,其中SnO2-HNO3-3的光催化效率最高,而SnO2-NH3几乎无可见光催化活性；(2)催化剂的投加量和Cr(VI)溶液的初始浓度影响SnO2-HNO3-3光催化还原Cr(VI)的速率；(3)光催化反应后,Cr(VI)被还原为Cr(III)。2.以Ce(NO3)3-6H2O, HNO3和甲苯为原料,采用溶剂热法,在180。C下加热24 h制得了立方相N掺杂Ce02纳米晶(Ce02-HN03)o利用XRD、TEM、HRTEM、XPS、Raman和UV-vis等测试手段表征了产物的组成、结构和光学性质。以可见光(λ420 nm)为光源、以K2Cr207水溶液为模型污染物,测试了所合成的N掺杂Ce02纳米晶光催化还原Cr(VI)的活性,并与CeO2-NH3(指用氨水代替硝酸,溶剂热合成的Ce02纳米晶)的光催化活性做了对比。结果表明：(1)CeO2-HNO3相比于CeO2-NH3表现出更高的可见光催化能力；(2)催化剂的投加量越大、Cr(VI)溶液的初始浓度越小,越有利于快速还原Cr(VI);(3)共存离子Cu2+、Fe3+、PO43、CH3COO和C2O42-影响CeO2-HNO3光催化还原Cr(VI)的效率,Na+、Mg2+、C1-和SO42-对CeO2-HNO3光催化还原Cr(VI)的效率基本无影响；(4)光催化反应后,Cr(VI)被还原为Cr(III)。3.以ZrCl4、HNO3和无水乙醇为原料,采用溶剂热法,在180。C加热12-24 h制得了一系列立方相N掺杂Zr02纳米材料(为了便于表述,我们将反应时间为12、18和24 h时所制产物分别标记为ZrO2-HNO3-12、ZrO2-HNO3-18和ZrO2-HNO3-24)。利用XRD、XPS、 FTIR、TEM、HRTEM和UV-vis等测试手段表征了产物的组成、结构和光学性质。以可见光(λ420 nm)为光源、以K2Cr207水溶液为模型污染物,研究了不同反应时间所合成的N掺杂ZrO2纳米晶光催化还原Cr(VI)的性质,并与ZrO2-NH3(指以氨水代替硝酸,溶剂热合成的zrO2纳米晶)的光催化活性做了对比。结果表明：(1)在可见光(λ420 nm)照射下,以HN03为氮源制得的Zr02对Cr(VI)的还原表现出很高的可见光催化活性,然而以NH3H2O为氮源合成的ZrO2不具有可见光催化活性；(2)催化剂的投加量、Cr(VI)溶液的初始浓度和pH值均影响ZrO2-HN03光催化还原Cr(VI)的效率；(3) ZrO2-HNO3的合成反应时间影响产物的光催化效率；(4)光催化反应后,Cr(VI)被还原为Cr(III)。
[Abstract]:Semiconductor photocatalytic reduction technology is a promising method for treating Cr (VI) wastewater, and developing efficient, stable, economical and non-toxic visible light catalyst is the key to realize its industrial application. Although SnO2, CeO2 and Zr02 have the advantages of stable, low cost and non-toxic as the photocatalyst materials, but they are all wideband gap and semi conductors. The bulk materials (the band gap values of Sn02, Ce02 and Zr02 are 3.8,3.2 and 5 eV respectively), mainly absorbing ultraviolet light in the solar light (ultraviolet light is only about 5% of the solar energy), which greatly affects the photocatalytic activity of these photocatalysts, limiting their actual applications in the field of photocatalysis. Therefore, the broadband gaps of SnO2, CeO2 and Zr02 are half the half gap. It is one of the important means to develop new efficient visible light catalysts for the modification of conductor materials to broaden their optical response range and improve their visible photocatalytic activity. This paper mainly studies the solvent thermal synthesis of N modified SnO2, CeO2 and Zr02 nanocrystals and the application of Cr (VI) in the photocatalytic treatment of water. The following can be summarized as follows: 1. a series of tetragonal N doped Sn02 nanomaterials (SnO2-HNO3-1, SnO2-HNO3-2 and SnO2-HNO3-3) were synthesized with SnCl4-5H2O, different dosage of HN03 and anhydrous ethanol as raw materials, using solvothermal method and 12 h at 180.C heating. X- ray diffraction (XRD), electron microscope (TEM), ray photoelectron spectroscopy, and Fu Liye The composition, structure and optical properties of the obtained products were characterized by transform infrared spectroscopy (FT-IR) and UV visible diffuse reflectance spectroscopy (UV-vis). The photocatalytic activity of N doped Sn02 Nanomaterials Synthesized under different nitric acid conditions was investigated with visible light (lambda 420 nm) as light source and K2Cr2O7 aqueous solution as model contaminant. The photocatalytic activity of SnO2-NH3 (Sn02 nanocrystals synthesized with ammonia water instead of nitric acid and solvent thermal synthesis) was compared. The results showed that (1) SnO2-HNO3-1, SnO2-HNO3-2 and SnO2-HNO3-3 showed high visible photocatalytic activity to the reduction of Cr (VI) under the irradiation of visible light ([lambda] 420 nm), and the photocatalytic efficiency of SnO2-HNO3-3 was the highest and SnO2-NH3 was the highest. There is almost no visible light catalytic activity; (2) the dosage of the catalyst and the initial concentration of Cr (VI) solution affect the rate of SnO2-HNO3-3 photocatalytic reduction of Cr (VI); (3) after the photocatalytic reaction, Cr (VI) is reduced to Cr (III).2. with Ce (NO3), and toluene as the raw material. Nanocrystalline (Ce02-HN03) O characterized the composition, structure and optical properties of the products by means of XRD, TEM, HRTEM, XPS, Raman and UV-vis. The photocatalytic activity of photocatalytic reduction of N doped Ce02 nanocrystals was tested by using visible light (lambda 420 nm) as the light source and K2Cr207 aqueous solution as the model pollutant. The photocatalytic activity of acid, solvothermal synthesis of Ce02 nanocrystals was compared. The results showed that (1) CeO2-HNO3 showed higher visible photocatalytic ability than CeO2-NH3; (2) the greater the dosage of the catalyst, the smaller the initial concentration of the Cr (VI) solution, the more conducive to the rapid reduction of Cr (VI); (3) the coexisting ions Cu2+, Fe3+, PO43, CH3COO, and C2O42- shadow. The efficiency of CeO2-HNO3 photocatalytic reduction of Cr (VI), Na+, Mg2+, C1- and SO42- has no effect on the efficiency of CeO2-HNO3 photocatalytic reduction of Cr (VI). (4) after the photocatalytic reaction, Cr (VI) is reduced to the raw material. Material (for ease of expression, we mark the reaction time at 12,18 and 24 h as ZrO2-HNO3-12, ZrO2-HNO3-18 and ZrO2-HNO3-24 respectively). Using XRD, XPS, FTIR, TEM, HRTEM and UV-vis, the composition, structure and optical properties of the products are characterized. The visible light (lambda 420 nm) is the light source and the water solution is the model pollution. The properties of photocatalytic reduction of Cr (VI) by N doped ZrO2 nanocrystals synthesized at different reaction time were studied. The photocatalytic activity of ZrO2-NH3 (the zrO2 nanocrystals synthesized with ammonia water instead of nitric acid and solvent heat) was compared. The results showed: (1) the reduction table of Zr02 to Cr (VI) produced by HN03 as nitrogen source under visible light (lambda 420 nm) High visible photocatalytic activity is shown, but ZrO2 synthesized with NH3H2O as nitrogen source does not have visible photocatalytic activity; (2) the dosage of the catalyst, the initial concentration of Cr (VI) solution and the pH value all affect the efficiency of the ZrO2-HN03 photocatalytic reduction of Cr (VI); (3) the reaction time of ZrO2-HNO3 affects the photocatalytic efficiency of the product; (4) photocatalysis After the reaction, Cr (VI) was reduced to Cr (III).
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;O643.36

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