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1.
钙钛矿型LaxSr1-xNi1-yCoyO3光电催化活性研究 总被引:8,自引:0,他引:8
用甘氨酸-硝酸盐燃烧合成法, 制备LaxSr1-xNi1-yCoyO3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LaxSr1-xNi1-yCoyO3的催化性能. 结果表明: LaxSr1-xNi1-yCoyO3 (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; LaxSr1-xNi1-yCoyO3的光催化活性高于LaxSr1-xNiO3, 这与B位离子(Ni2—, Co2-)的电子构型有关; Co2+的加入可使LaxSr1-xNiO3的光催化活性有所提高. 相似文献
2.
采用高温固相法在空气中合成了Ba1.97-yZn1-xMgxSi2O7:0.03Eu,yCe3+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Ba1.97-yZn1-xMgxSi2O7:0.03Eu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Eu2+离子的4f65d1-4f7跃迁,590~725 nm红光区窄带谱源于Eu3+的5D0-7FJ (J=1,2,3,4)跃迁,这表明,在空气气氛中,部分Eu3+在Ba1.97-yZn1-xMgxSi2O7基质中被还原成了Eu2+;当x=0.1时,荧光粉Ba1.97Zn0.9Mg0.1Si2O7:0.03Eu的绿色发光最强,表明Eu3+被还原成Eu2+离子的程度最大。当共掺入Ce3+离子后,形成Ba1.97-yZn0.9Mg0.1Si2O7:0.03Eu,yCe3+荧光粉体系,其发光随着Ce3+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Ba1.96Zn0.9Mg0.1Si2O7:0.01Ce3+,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Ba2Zn0.9Mg0.1Si2O7基质中的能量传递与发光机理。 相似文献
3.
CeCl3-CdCl2-H2O和CeCl3-CdCl2-HCl-H2O的相平衡 总被引:5,自引:0,他引:5
测定了三元系CeCl3-CdCl2-H2O (25 ℃)和四元系CeCl3-CdCl2-HCl(~8.4%)-H2O(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CdCl2&;#8226;2.5H2O(原始盐)、CdCl2&;#8226;H2O(原始盐)、6CdCl2&;#8226;CeCl3&;#8226;14H2O、4CdCl2&;#8226;CeCl3&;#8226;12H2O、CeCl3&;#8226;7H2O(原始盐)组成的复杂体系.该四元系是由5个固相区CdCl2&;#8226;H2O(原始盐)、9CdCl2&;#8226;CeCl3&;#8226;19H2O、6CdCl2&;#8226;CeCl3&;#8226;14H2O、4CdCl2&;#8226;CeCl3&;#8226;12H2O、CeCl3&;#8226;7H2O(原始盐)组成的复杂体系.其中6CdCl2&;#8226;CeCl3&;#8226;14H2O在该三元系是介稳化合物.9CdCl2&;#8226;CeCl3&;#8226;19H2O 、6CdCl2&;#8226;CeCl3&;#8226;14H2O和4CdCl2&;#8226;CeCl3&;#8226;12H2O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
4.
纳米钙钛矿LaxSr1-xFe1-yCoyO3复合氧化物的制备和表征 总被引:1,自引:0,他引:1
用甘氨酸-硝酸盐燃烧合成法,制备LaxSr1-xFe1-yCoyO3复合氧化物的陶瓷粉末,对该钙钛矿型氧化物进行了XRD、IR、紫外漫反射光谱及循环伏安曲线分析。结果表明:该复合氧化物粉体平均晶粒为15.3~29.8 nm,为立方和正交晶系。该氧电极具有双功能催化特性,但不完全可逆。对水溶液染料进行光解实验,利用紫外-可见、人工神经网络光度法研究LaxSr1-xFe1-yCoyO3的催化性能。结果表明:CO2+的加入可使LaxSr1-xFeO3的光催化活性有所提高,B位离子(Fe3+,CO2+)改变与加入,使LaxSr1-xFe1-yCoyO3(x=0.7,0.3;y=0.3,0.9,1)光催化活性高于LaxSr1-xFeO3。同时,对5种染料进行紫外光解,在0.75 h,脱色率大于91%,并为动力学一级反应。 相似文献
5.
溴代烷烃与活性氮的反应发光研究 总被引:1,自引:0,他引:1
在流动余辉装置上, 利用N2空心阴极放电制备活性氮, 研究了活性氮与溴代烷烃(CHBr3、CH2Br2、C2H5Br、C4H9Br) 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
6.
The luminescent properties of Pr3+-doped LaB3O6, SrAl12O19, SrB4O7 and NaYF4 in the vaccum ultraviol-et (VUV) range at different temperatures were investigated under the excitation of high-energetic synchrotron radiation. For Pr3+ ions in LaB3O6, SrAl12O19 and SrB4O7, only the parity-forbidden 1S0→4f2 transitions were observ-ed in the emission spectra at relatively low temperature; but the parity-allowed 4f5d→4f2 transitions appeared simultaneously when the temperature was high enough. And the intensity of broad 4f5d→4f2 emission increased relative to the intensity of 1S0→4f2 emissions with increasing temperature. Then the thermal equilibrium model of energy levels was employed to the lowest 4f5d state and 1S0 state of Pr3+ 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 4f5d states at high temperatures when the lowest 4f5d state lies higher than 1S0 state and the photon energy is high enough. 相似文献
7.
8.
报道了采用气相法对PbTiO3陶瓷扩渗La-Ce混合稀土元素的研究. 在气相扩渗过程中, La, Ce与PbTiO3陶瓷组元发生了复杂反应,生成了稀土化合物La2Ti6O15和CeTi21O38, 制备出未见报道的La2Ti6O15-CeTi21O38-PbTiO3陶瓷材料, 经测试其导电性能发生了十分显著的变化. La2Ti6O15-CeTi21O38-PbTiO3陶瓷材料的室温电阻率从2.0 ×1010 W·m下降为0.248 W·m,而且随着温度的变化, 晶粒电阻呈现明显的PTCR效应,而晶界电阻随着温度的升高,呈急剧连续降低状态,总电阻的变化规律与晶界电阻的变化相一致, 试样总电阻的PTCR效应已不存在, 近趋导体. 经XPS测试分析, 进一步证实了La2Ti6O15-CeTi21O38-PbTiO3陶瓷材料中铅、钛等元素均有变价, 因而导致了La2Ti6O15-CeTi21O38-PbTiO3陶瓷材料电阻率的降低, 测试结果还首次给出了La2Ti6O15-CeTi21O38-PbTiO3陶瓷材料中各元素结合能位置的峰值. TG-DTA热分析表明La2Ti6O15-CeTi21O38-PbTiO3陶瓷材料具有较好的高温热稳定性. 相似文献
9.
采用简单沉积-沉淀法合成了Bi2WO6@Bi2MoO6-xF2x(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Bi2WO6@Bi2MoO6-xF2x异质结的光催化活性增强机制。形貌分析表明,所得Bi2MoO6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Bi2WO6量子点均匀沉积在Bi2MoO6-xF2x微球表面,形成新颖的Bi2WO6@Bi2MoO6-xF2x异质结;与纯Bi2MoO6或者Bi2WO6相比,1∶1Bi2WO6@Bi2MoO6-xF2x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,Bi2WO6量子点表面沉积显著提高Bi2MoO6-xF2x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·O2-和h+是主要的活性物种。根据实验结果,探讨了F-掺杂和Bi2WO6量子点之间的协同效应对Bi2MoO6的光催化活性的影响机制。 相似文献
10.
The precursor ZrW1.6Mo0.4O7(OH)2(H2O)2 was characterized by IR and XRD methods. δ′-ZrW1.6Mo0.4O8 was prepared by careful controlling the annealing conditions from the precursor and was determined to have the formula as o-ZrW1.6Mo0.4O8·H2O by TG-DSC, IR, and XRD methods. The relation between o-ZrW1.6Mo0.4O8·H2O and o-ZrW1.6Mo0.4O8 was discussed through variable temperature XRD patterns. Further more, the mechanism of the precursor dehydration was suggested. 相似文献
11.
用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%. 相似文献
12.
Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields. 相似文献
13.
The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula. 相似文献
14.
Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction
Laurent Gavara Thomas Boisse Jean-Pierre Hénichart Adam Daïch Philippe Gautret 《Tetrahedron》2010,66(38):7544-5571
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments. 相似文献
15.
Rebecca J. Burton Mandy L. CrowtherNeal J. Fazakerley Shaun M. FilleryBarry M. Hayter Jason G. KettleCaroline A. McMillan Paula PerkinsPeter Robins Peter M. SmithEmma J. Williams Gail L. Wrigley 《Tetrahedron letters》2013
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines. 相似文献
16.
KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields. 相似文献
17.
N. A. Nedolya 《Chemistry of Heterocyclic Compounds》2008,44(10):1165-1219
The review contains a concise historical account and information on the most significant researches undertaken by the staff
at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry
of Heterocyclic Compounds.
Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008. 相似文献
18.
Regiospecific and direct imidation of the methyl C(sp3)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products. 相似文献
19.
A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL. 相似文献
20.
A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions. 相似文献