电沉积ZnO薄膜光催化还原Cr(Ⅵ)

采用电沉积法在导电玻璃上制备了ZnO薄膜,用X-射线衍射仪和扫描电子显微镜对其进行了表征.研究了各种因素对电沉积ZnO薄膜光催化还原Cr(Ⅵ)的影响.结果表明,空穴清除剂的存在是光催化还原Cr(Ⅵ)的重要条件;酸性介质中,Cr(Ⅵ)光催化还原率最高;Cr(Ⅵ)光催化还原率随Cr(Ⅵ)浓度的减小而增加;NO3 、SO42-和Ni2+等共存离子明显抑制了Cr(Ⅵ)的还原;而Cu2+则有着显著的促进作用.在pH=4.0和c(柠檬酸)为1.2mmol/L的条件下,经过60min的反应后,0.1mmol/LCr(Ⅵ)在ZnO薄膜上的光催化还原率达到96%.     

CuO/ZnO叠层复合薄膜的制备及其光催化活性

分别通过光还原和电还原在以氧化铟锡玻璃为基体的ZnO上沉积Cu和Cu2O,后经400℃空气中热处理,制备了两种CuO/ZnO叠层复合薄膜。用X射线衍射、扫描电子显微镜和X射线能量散射谱分别对复合薄膜的晶相、形貌和化学组成进行表征。以橙黄II在模拟自然光照射下的光催化降解作为探针反应评价其光催化活性。结果表明：由Cu/ZnO经400℃下焙烧1h转化的CuO/ZnO叠层复合薄膜具有更高的光催化活性,反应1h后,橙黄II的降解率比由Cu2O/ZnO经400℃下焙烧1h转化的CuO/ZnO提高了14%。对CuO/ZnO叠层复合薄膜光催化活性提高的原因也进行了讨论。     

氧化亚铜/氧化锌复合薄膜的制备及可见光催化研究

以导电玻璃(FTO)为基底,采用连续阴极电沉积方法在多孔结构的ZnO薄膜上合成具有单一(111)择优取向的Cu2O,制备了Cu2O/ZnO复合薄膜。采用X射线衍射和扫描电镜分别对薄膜的结构及形貌进行了表征。光吸收谱显示复合薄膜在可见光范围内具有较好的光吸收性能。可见光催化降解罗丹明B的实验表明,由于在两半导体接触界面上发生了电荷的转移,Cu2O/ZnO复合薄膜比单一的Cu2O薄膜具有更高的光催化活性,在2.5h内对罗丹明B的降解率可达到70%,而在相同条件下Cu2O薄膜的降解率仅为60%。     

Cu2O光催化还原含铬(Ⅵ)废水的研究

采用亚硫酸钠还原法制备了Cu2O光催化剂,并将其应用于含铬(Ⅵ)废水降解还原的光催化反应,同时与Bi2WO6、TiO2等光催化剂进行了活性比较.研究表明,在300W高压汞灯照射下反应1.5 h,Cu2O、Bi2WO6和TiO2光催化剂对铬(Ⅵ)的光催化还原降解率分别为69.5%、61.5%和44.2%,与其禁带宽度(2.O eV、3.O eV、3 2 eV)成反比,Cu2O较窄的禁带宽度使其具有良好的光催化活性.Cu2O光催化还原铬(Ⅵ)废水的适宜工艺条件为:废水的pH为3.O,Cu2O光催化剂用量为0.25 g·L-1.在上述工艺条件下,300W高压汞灯光照反应时间4 h后,废水中的铬(Ⅵ)有82%被还原.采用微分法对Cu2O光催化还原含铬(Ⅵ)废水反应进行了化学动力学研究,其光催化反应速率方程为:v=0.681CCr2.7.     

Al2O3/TiO2复合膜的结构及光催化性能

利用电沉积方法在铝硫酸阳极氧化膜表面制备了具有光催化活性的T iO2薄膜。分析了A l2O3/T iO2复合膜的结构,观察了薄膜表面形貌及断面构造,并分析了薄膜表面的化学成分,通过紫外光照射下甲基橙溶液的光催化降解反应初步研究了该复合膜的光催化活性。结果表明,未经热处理的A l2O3/T iO2复合膜处于非晶态,550℃热处理3 h后,T iO2转变为锐钛矿结构;沉积在铝氧化膜表面的T iO2薄膜厚度约5μm,呈均匀不连续状态,表面存在大量裂纹,电沉积T iO2过程中基体氧化铝存在着部分溶解;薄膜表面主要由T i、O两种元素构成,同时存在较少量的A l、S、K等元素。该A l2O3/T iO2复合膜可光催化降解甲基橙溶液,具有光催化活性。     

p-n异质结ZnO/HRP催化剂的制备及其光催化性能研究

p型半导体红磷(HRP)和n型半导体ZnO复合后形成p-n型异质结复合半导体催化剂ZnO/HRP。以Cr(Ⅵ)为模型污染物,研究了ZnO质量分数对催化剂光催化还原性能的影响。结果发现,ZnO/HRP复合光催化剂的光催化还原速率随ZnO质量分数的增加而增大,当ZnO的质量分数为0. 25%时,ZnO/HRP复合光催化剂展现出最强的光还原性,其降解速率常数k为5. 5×10^-2min^-1,是HRP的14. 8倍。光催化机理探究发现,Zn O和HRP复合形成异质结后,可抑制光生电子和空穴的复合,增强光响应性,从而提高了HRP的光催化活性。     

pH对电沉积氧化亚铜薄膜的影响及光催化性能

以导电玻璃为阴极,在不同pH下,从含有0.083mol/LCu(CH3COO)2·H2O、0.22mol/L乳酸的电解液中电沉积合成Cu2O薄膜。研究了电解液pH对Cu2O薄膜晶体择优取向和形貌的影响。结果表明,通过调节电解液pH可合成不同择优取向和形貌的Cu2O薄膜,在pH为7～13内合成的Cu2O薄膜均具有较好的光吸收性。pH=11时,可制得具有(111)取向、结合力强、光催化活性高和稳定性好的Cu2O薄膜。Cu2O薄膜的晶面类型对薄膜催化能力有较大影响,(111)择优取向的Cu2O薄膜的光催化活性最高,反应2.5h后罗丹明B的降解率可达63%。     

活性炭掺杂WO_3/ZnO复合薄膜制备及其光催化性能研究

采用溶胶-凝胶法在铝箔上制备WO3/ZnO复合薄膜,并用活性炭对其改性,以甲基橙水溶液模拟有机污染物,研究了WO3/ZnO薄膜的光催化降解性能。实验结果表明:白炽灯照射2h、WO3质量分数为2.5%时,WO3/ZnO/铝箔对甲基橙的降解率达到78.54%;紫外光照射下降解率达到99.89%。当活性炭掺杂量为10g/L时,制得的WO3/ZnO复合薄膜均匀一致且光催化性能良好,可见光照射下甲基橙降解率达到85.71%。     

Ag-Cu2O复合薄膜的制备及其光催化活性

先采用阴极电沉积,在导电玻璃基体上合成Cu2O薄膜,然后以AgNO3为反应溶液,通过浸渍的方式制备出了Ag-Cu2O复合薄膜。利用X-射线衍射仪、扫描电子显微镜和能谱仪进行了表征。以光催化降解甲基橙为探针反应,测试光催化活性。结果表明,Ag-Cu2O复合薄膜的光催化活性和单一的Cu2O相比有了显著提高。并对Ag-Cu2O薄膜光催化活性提高的原因进行了讨论。     

Ti/SnO_2/ZnO复合薄膜的制备及其光催化性能研究

以Ti/SnO2为基体,从Zn(NO3)2水溶液中阴极电沉积ZnO,制备了Ti/SnO2/ZnO复合薄膜,用X-射线衍射、扫描电子显微镜和紫外可见漫反射吸收光谱对其进行了表征,以甲基橙为目标有机物,考察了其光催化活性.实验结果表明,Ti/SnO2/ZnO复合薄膜的光催化活性明显高于Ti/ZnO薄膜,且其催化活性随ZnO的沉积时间而变化.对复合薄膜催化活性提高的原因进行了讨论.     

CuO and CuO-ZnO catalysts supported on CeO2 and CeO2-LaO3 for low temperature water-gas shift reaction

This paper describes an investigation on CuO and CuO-ZnO catalysts supported on CeO₂ and CeO₂-La₂O₃ oxides, which were designed for the low temperature water-gas shift reaction (WGSR). Bulk catalysts were prepared by co-precipitation of metal nitrates and characterized by energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), surface area (by the BET method), X-ray photoelectron spectroscopy (XPS), and in situ X-ray absorption near edge structure (XANES). The catalysts' activities were tested in the forward WGSR, and the CuO/CeO₂ catalyst presented the best catalytic performance. The reasons for this are twofold: (1) the presence of Zn inhibits the interaction between Cu and Ce ions, and (2) lanthanum oxide forms a solid solution with cerium oxide, which will cause a decrease in the surface area of the catalysts. Also the CuO/CeO₂ catalyst presented the highest Cu content on the surface, which could influence its catalytic behavior. Additionally, the Cu⁰ and Cu¹⁺ species could influence the catalytic activity via a reduction-oxidation mechanism, corroborating to the best catalytic performance of the Cu/Ce catalyst.     

(锌、铜、锰)复合脱硫剂的制备及性能研究

用共沉淀法制备纳米脱硫剂前躯物,以硅铝酸盐为载体造粒成型,经450℃煅烧6h得到三元金属氧化物脱硫剂,此脱硫剂在240℃无氧条件下精脱H2S,且颗粒平均直径为1.0mm时,其穿透硫容可达33.5%,是一种适合于中低温条件下脱硫的脱硫剂。     

金属氧化物吸收微波辐射的能力与其结构的关系

考察了８种金属氧化物及６种复合金属氧化物在微波场中的升温行为，并对升温行为与其结构的关系进行了初步探讨。     

中国专用氧化镁开发现状及其发展建议

介绍了氧化镁系列产品应用领域及生产现状,中国专用氧化镁如活性氧化镁、电工级氧化镁、硅钢级氧化镁、高纯氧化镁等开发是成功的,其中高纯氧化镁已达到世界领先水平;硅钢级氧化镁不仅已工业化,并成功应用于武钢硅钢片的生产上,取得显著经济效益,但总体上看研发技术虽然成功,工业化生产量还不足。提出了中国专用氧化镁发展必须充分利用中国十分丰富镁资源,扬长避短,发挥原料及生产方法优势,采用先进设备,提升装置及自控水平,建立万吨级骨干企业,提高专用化率等建议,提高精细氧化镁品种及产量以满足国内外市场需求。     

Sintering of Zinc Oxide Doped with Antimony Oxide and Bismuth Oxide

The phase change, densification, and microstructure development of ZnO doped with both Bi₂O₃ and Sb₂O₃ are studied to better understand the sintering behavior of ZnO varistors. The densification behavior is related to the formation of pyrochlore and liquid phases; the densification is retarded by the former and promoted by the latter. The pyrochlore phase, whose composition is Bi_3/2ZnSb_3/2O₇, appears below 700°C. The formation temperature of the liquid phase depends on the Sb/Bi ratio: about 750°C for Sb/Bi < 1 by the eutectic melting in the system ZnO—Bi₂O₃, and about 1000°C for Sb/Bi > 1 by the reaction of the pyrochlore phase with ZnO. Hence, the densification rate is determined virtually by the Sb/Bi ratio and not by the total amount of additives. The microstructure depends on the sintering temperature. Sintering at 1000°C forms intragrain pyrochlore particles in ZnO grains as well as intergranular layers, but the intragrain particles disappear at 1200°C by the increased amount of liquid phase, which enhances the mobility of the solid second phase.     

非水解溶胶-凝胶过程制备锡/硅复合氧化物

以无水四氯化锡和正硅酸乙酯为前驱物、环己烷为溶剂,在无氧无水条件下采用非水解溶胶-凝胶过程制备了锡/硅复合氧化物,并对其进行了表征分析。结果表明,在原料Sn/Si摩尔比为1∶2、反应温度为30℃、焙烧温度为500℃时,所得复合氧化物的产率为31.3%,Sn/Si摩尔比为7.4∶1,粒径10nm左右,比表面积22.58cm2.g-1,平均孔径14.3nm,比孔容0.047cm3.g-1,主要为颗粒堆积孔;复合氧化物的主要组成为无定形氧化硅和氧化锡晶体,在焙烧温度达到500～600℃时仍有Sn-O-Si杂键存在。     

纯正黑色釉的研制

研究了用金属氧化物和硅酸盐材料直接制取纯正黑色釉的可行性，探讨了氧化铁、氧化铝、氧化钢、氧化信和氧化锰对黑釉性质的影响。     

氧化钛对氧化铬材料烧结特性的影响

以Cr_2O_3微粉和TiO_2微粉为主要原料,聚乙烯醇为结合剂,经制浆、喷雾造粒、机压和等静压二次成型,在气氛炉内(氧分压分别控制在10Pa和0.1Pa),1 500℃保温3h烧成制备氧化铬样品.研究了氧化钛加入量(质量分数为1%～5%)对Cr_2O_3材料烧结特性的影响.结果表明:TiO_2能显著促进Cr_2O_3材料的烧结,随着TiO_2加入量的增加,样品的体积密度迅速增加,显气孔率迅速下降;加入3%TiO_2基本能全部固溶到Cr_2O_3晶粒内,形成固溶体;当TiO_2的加入量超过3%时,富余部分形成钛铬化合物Cr_2Ti_(n-2)O_(2n-1)(3相似文献   

Differences in Wetting Characteristics of Bi2O3 Polymorphs in ZnO Varistor Materials

Detailed analysis of the microstructure of grain boundaries, especially triple-grain and multiple-grain junctions, in ZnO varistor materials has been performed using transmission electron microscopy. Different polymorphs of Bi₂O₃ are shown to exhibit different wetting properties on ZnO interfaces. Recent investigations suggest that the equilibrium configuration consists of crystalline Bi₂O₃ in the triple-grain and multiple-grain junctions and an amorphous bismuth-rich film in the ZnO/ZnO grain boundaries. The present investigation supports this suggestion for δ-Bi₂O₃ and also adds to the microstructural image and wetting properties of α-Bi₂O₃.     

Effect of Additives on the Hydration Resistance of Materials Synthesized from the Magnesia–Calcia System

The effect of a variety of doping additives on the hydration resistance of calcined materials in the MgO–CaO system was investigated. Samples were prepared from lightly calcined flotation magnesite that was mixed with dolomite, as well as from analytically pure CaO and MgO; then, the samples were doped with additives that contained cations with various valences (monvalent to tetravalent). Both the hydration rate and the powdering rate were measured. The important role of the higher-valence cations in improving the hydration resistance of the MgO–CaO materials was revealed. This behavior is believed to be due to the formation of vacancies in solid solutions of CaO or MgO with higher-valence cations. The Ti⁴⁺ cation forms a solid solution with CaO, which reduces the Ca²⁺ concentration and leads to the improved hydration resistance of calcined materials from the MgO–CaO system.