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1.
采用简单沉积-沉淀法合成了Bi 2WO 6@Bi 2MoO 6-xF 2x(BWO/BMO6-xF2x)异质结,借助XRD、XPS、TEM、SEM、EDS、UV-Vis-DRS、PC和EIS等测试技术对其组成、形貌、光吸收特性和光电化学性能等进行系统表征,并以模型污染物罗丹明B(RhB)的光催化降解作为探针反应来评价Bi 2WO 6@Bi 2MoO 6-xF 2x异质结的光催化活性增强机制。形貌分析表明,所得Bi 2MoO 6微球由大量厚度为20~50 nm的纳米片组成;FE-SEM和HR-TEM分析表明,尺寸约为10 nm的Bi 2WO 6量子点均匀沉积在Bi 2MoO 6-xF 2x微球表面,形成新颖的Bi 2WO 6@Bi 2MoO 6-xF 2x异质结;与纯Bi 2MoO 6或者Bi 2WO 6相比,1∶1Bi 2WO 6@Bi 2MoO 6-xF 2x异质结表现出更好的光催化活性和光电流性质,其对RhB光催化降解的表观速率常数分别为纯BMO和BWO的6.4和11.6倍。PC和EIS图谱分析表明,Bi 2WO 6量子点表面沉积显著提高Bi 2MoO 6-xF 2x光生电子/空穴的分离效率和迁移速率;活性物种捕获实验证明了·O 2-和h +是主要的活性物种。根据实验结果,探讨了F -掺杂和Bi 2WO 6量子点之间的协同效应对Bi 2MoO 6的光催化活性的影响机制。 相似文献
2.
在流动余辉装置上, 利用N 2空心阴极放电制备活性氮, 研究了活性氮与溴代烷烃(CHBr 3、CH 2Br 2、C 2H 5Br、C 4H 9Br) 反应的化学发光.上述所有反应中, 在550~750 nm波段均观察到了较强的NBr ( b1Σ+→X3Σ-)跃迁发射谱. 同时在活性氮与CHBr3和CH2Br2的反应中, 在流动管下游还观察到了CN (A2π, B2π→X2Σ+)的发射谱. 验证性的实验表明, 激发态NBr (b1Σ+)是由二步过程形成: N(4S)与溴代烷烃反应生成NBr (X3Σ-), 再通过N2 (A 3Σu+)分子能量转移到激发态NBr (b1Σ+); 而激发态的CN是通过N(4S) + CBr→CN(A, B) + Br过程形成的. 相似文献
3.
The equilibrium solubilities of the ternary system YCl 3-CdCl 2-H 2O, the quaternary system YCl 3-CdCl 2-HCl(~8.8%)-H 2O were determined at 25 ℃ and the phase diagrams were constructed. The results show that the ternary system was complicated with six equilibrim solid phases CdCl 2·2.5H 2O, CdCl 2·H 2O, 8CdCl 2·YCl 3·15H 2O (8∶1 type), 4CdCl 2·YCl 3·13H 2O(4∶1 type), 5CdCl 2·2YCl 3·26H 2O (5∶2 type) and YCl 3·6H 2O. The quaternary system was also complicated with four equilibrim solid phase CdCl 2·H 2O, 4CdCl 2·YCl 3·13H 2O (4∶1 type), 5CdCl 2·2YCl 3·26H 2O(5∶2 type) and YCl 3·6H 2O. Among the three new compounds 8CdCl 2·YCl 3·15H 2O, 4CdCl 2·YCl 3·13H 2O and 5CdCl 2·2YCl 3·26H 2O, 8CdCl 2·YCl 3·15H 2O was a kind of metastable compound only in ternary system, and it was changed into 4CdCl 2·YCl 3·13H 2O with time. Both 4∶1 type and 5∶2 type existed in ternary and quaternary system, but they were also congruently soluble compounds in quaternary system. They have been prepared from the system and have been characterized by XRD, TC-DTG and DSC. 相似文献
4.
用甘氨酸-硝酸盐燃烧合成法, 制备La xSr 1-xNi 1-yCo yO 3复合氧化物的陶瓷粉末, 对钙钛矿氧化物进行了XRD结构分析. 在通氧或不通氧下测试氧还原和氧析出的循环伏安曲线. 结果表明: 该氧电极具有双功能催化特性, 但不完全可逆. 利用汞灯作为激发光源, 进行几种水溶性染料和五种混合染料光解实验, 利用紫外-可见、红外以及人工神经网络光度法研究La xSr 1-xNi 1-yCo yO 3的催化性能. 结果表明: La xSr 1-xNi 1-yCo yO 3 ( x=0.7, 0.9, 1; y=0.3, 0.75)复合氧化物都具有较强光催化特性; La xSr 1-xNi 1-yCo yO 3的光催化活性高于La xSr 1-xNiO 3, 这与B位离子(Ni 2—, Co 2-)的电子构型有关; Co 2+的加入可使La xSr 1-xNiO 3的光催化活性有所提高. 相似文献
5.
Nanosize manganese zinc ferrites were fabricated by hydrothermal precipitation route using Fe 2(SO 4) 3, ZnSO 4·7H 2O, MnSO 4·H 2O as material, then some calcinated at 500 ℃ and studied by XRD, TEM, IR and VSM. The results showed that the products were spinel crystal structure and uniformly sized nanoparticles (15~25 nm) with little aggregation. The analysis of IR showed that the superficial water can be eliminated, but that was embedded in crystal lattice can not be removed by calcinating. The effect Zn content x on the lattice ( a) of nanosize Mn 1-xZn xFe 2O 4 was also discussed. The lattice of nanosize Mn 1-xZn xFe 2O 4 decreases with x increasing; and its value deviated the standard lattice ( a0) of normal size manganese zinc ferrites. A lot of water was absorbed during the hydrothermal process owing to the large surface of nanosize particles. The change of magnetic properties of Mn xZn 1-xFe 2O 4 with x increasing was studied: nanosize Mn xZn 1-xFe 2O 4 particles synthesized by us exhibited peculiar magnetic properties curve with Zn content ( x) increasing, Superparamagnetic behaviors of the synthesized ZnFe 2O 4 samples were confirmed by magnetic characterization, which can be explained by the difference between the distribution of the metal ions (Mn 2+, Zn 2+ and Fe 3+) among the tetrahedral (A) and the octahedral (B) sites of nanosize ferrite and that of bulk ferrite. 相似文献
6.
利用基于密度泛函理论的第一性原理赝势法设计并优化了含稀土元素的新半金属Fe 2LaO 4。详细计算了其电荷分布,分子磁矩等磁电性能,并结合配位场理论分析了其电子结构。结果表明,Fe 2LaO 4是一种含稀土元素的铁磁性的新ⅡB型半金属;它的稳定相晶格常数约为0.623 nm,分子磁矩约为1.0μ B;Fe 2LaO 4属软铁磁性半金属;La较多的外层电子增强了Fe 2LaO 4内部的库仑斥力,导致了配合物ML 4和ML 6均受强场作用,从而使Fe 2LaO 4具有软铁磁性;考虑自旋分布后ML 4和ML 6的电子结构分别为 a1g1↑ a1g1↓ t1u3↑ t1u3↓ eg2↑ eg2↓ t2g3↑ t2g3↓和 a1g1↑ a1g1↓ t1u3↑ t1u3↓ t2g3↑ t2g3↓ eg2↑ eg2↓ eg*1↑,这些电子属于分子轨道。 相似文献
7.
The luminescent properties of Pr 3+-doped LaB 3O 6, SrAl 12O 19, SrB 4O 7 and NaYF 4 in the vaccum ultraviol-et (VUV) range at different temperatures were investigated under the excitation of high-energetic synchrotron radiation. For Pr 3+ ions in LaB 3O 6, SrAl 12O 19 and SrB 4O 7, only the parity-forbidden 1S0→4 f2 transitions were observ-ed in the emission spectra at relatively low temperature; but the parity-allowed 4 f5 d→4 f2 transitions appeared simultaneously when the temperature was high enough. And the intensity of broad 4 f5 d→4 f2 emission increased relative to the intensity of 1S0→4 f2 emissions with increasing temperature. Then the thermal equilibrium model of energy levels was employed to the lowest 4 f5 d state and 1S0 state of Pr 3+ in the three hosts. The calculated curves were in good agreement with the experimental values, indicating the occurrence of the thermal excitation from 1S0 state to 4 f5 d states at high temperatures when the lowest 4 f5 d state lies higher than 1S0 state and the photon energy is high enough. 相似文献
8.
采用高温固相法在空气中合成了Ba 1.97-yZn 1-xMg xSi 2O 7:0.03Eu, yCe 3+系列荧光粉。分别采用X-射线衍射和荧光光谱对所合成荧光粉的物相和发光性质进行了表征。在紫外光330~360 nm激发下,固溶体荧光粉Ba 1.97-yZn 1-xMg xSi 2O 7:0.03Eu的发射光谱在350~725 nm范围内呈现多谱峰发射,360和500 nm处有强的宽带发射属于Eu 2+离子的4 f65 d1-4 f7跃迁,590~725 nm红光区窄带谱源于Eu 3+的 5D0- 7FJ ( J=1,2,3,4)跃迁,这表明,在空气气氛中,部分Eu 3+在Ba 1.97-yZn 1-xMg xSi 2O 7基质中被还原成了Eu 2+;当 x=0.1时,荧光粉Ba 1.97Zn 0.9Mg 0.1Si 2O 7:0.03Eu的绿色发光最强,表明Eu 3+被还原成Eu 2+离子的程度最大。当共掺入Ce 3+离子后,形成Ba 1.97-yZn 0.9Mg 0.1Si 2O 7:0.03Eu, yCe 3+荧光粉体系,其发光随着Ce 3+离子浓度的增大由蓝绿区经白光区到达橙红区;发现名义组成为Ba 1.96Zn 0.9Mg 0.1Si 2O 7:0.01Ce 3+,0.03Eu的荧光粉的色坐标为(0.323,0.311),接近理想白光,是一种有潜在应用价值的白光荧光粉。讨论了稀土离子在Ba 2Zn 0.9Mg 0.1Si 2O 7基质中的能量传递与发光机理。 相似文献
9.
由高温固相反应制得Sr 0.955Al 2Si 2-xTi xO 8:Eu 2+( x=0~1.0)系列试样,研究了Ti 4+置换Si 4+对其晶体结构和光谱特性的影响。Ti 4+以类质同相替代Si 4+进入晶体晶格中,形成了连续固溶体,其晶胞参数 a,b,c,β和晶胞体积V随Ti 4+置换量呈线性递增。Ti 4+置换Si 4+对晶胞参数 c的影响显著, b其次, a最小。荧光激发谱为宽带,位于230~400nm,由267nm、305nm、350nm和375nm 4个峰拟合成,表观峰值位于351nm;随着Ti 4+置换量的增加,半高宽(FWHM)从105nm减小到93nm。发射光谱位于380~600nm,表观峰值位于407nm,可由406nm和441nm两峰拟合而成并且随Ti 4+置换量增加线性红移,Ti 4+进入晶格对长波长发射中心影响较少;Ti 4+置换量为1.0时,表观发射峰位从407nm红移至417nm;利用试样荧光光谱和VanUitert经验公式,得出SrAl 2Si 2O 8:Eu 2+中Sr 2+的配位数为9。随着Ti 4+置换量Si 4+进入基质晶格,造成Eu-O距离变小,使得Eu 2+所处的晶体场强度增强,发光中心Eu 2+的5d能级分裂增大,造成Eu 2+最低发射能级重心下移,两拟合谱峰峰位均呈线性红移。 相似文献
10.
测定了三元系CeCl 3-CdCl 2-H 2O (25 ℃)和四元系CeCl 3-CdCl 2-HCl(~8.4%)-H 2O(25 ℃) 的相平衡溶度数据,绘制了相应的溶度图.该三元系是由5个固相区CdCl 2&;#8226;2.5H 2O(原始盐)、CdCl 2&;#8226;H 2O(原始盐)、6CdCl 2&;#8226;CeCl 3&;#8226;14H 2O、4CdCl 2&;#8226;CeCl 3&;#8226;12H 2O、CeCl 3&;#8226;7H 2O(原始盐)组成的复杂体系.该四元系是由5个固相区CdCl 2&;#8226;H 2O(原始盐)、9CdCl 2&;#8226;CeCl 3&;#8226;19H 2O、6CdCl 2&;#8226;CeCl 3&;#8226;14H 2O、4CdCl 2&;#8226;CeCl 3&;#8226;12H 2O、CeCl 3&;#8226;7H 2O(原始盐)组成的复杂体系.其中6CdCl 2&;#8226;CeCl 3&;#8226;14H 2O在该三元系是介稳化合物.9CdCl 2&;#8226;CeCl 3&;#8226;19H 2O 、6CdCl 2&;#8226;CeCl 3&;#8226;14H 2O和4CdCl 2&;#8226;CeCl 3&;#8226;12H 2O用X射线粉末衍射及TG-DTG和DSC等方法进行了研究,并对X射线粉末衍射进行了指标化. 相似文献
11.
The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted
indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator
model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was
established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing
analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom.
Translated from Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997. 相似文献
12.
非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。 相似文献
13.
The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness. 相似文献
14.
Two vanilloids, (5 E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one ( 1) and 4-[3-hydroxydecyl]-2-methoxyphenol ( 2), isolated from the dried seeds of Grains of Paradise ( Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared. 相似文献
15.
针对恶臭测试的环境影响问题,提出了解决的实例方案,并对方案的要点及优缺点进行讨论,此方案在实际操作中具有较好的效果。 相似文献
16.
用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。 相似文献
17.
In this review, the research of the author in the field of colloidal systems is summarized. The factors influencing colloidal stability are systematized and analyzed. Examples are presented to illustrate the practical utilization of the theory of stability of colloids and thin films.This review was prepared on the basis of the works of the author, which were awarded the State Premium for 1991 in the field of science and technology, chemistry section.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1708–1717, August, 1992. 相似文献
18.
Main hydration products of two cement pastes, i.e. CSH-gel, portlandite ( P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time ( th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, M o, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with ( th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with ( th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700 oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
19.
面对日益枯竭的能源危机,氢能是一种洁净、最有前景的替代能源。目前在各种制氢的方法中光催化分解水制氢的研究最多,光解水过程中催化剂最关键,本文对利用太阳能光解水的途径、提高光催化反应效率以及光催化剂的开发研究进行了综述。 相似文献
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