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ZnO纳米粒子的表面光电压谱和光催化性能 总被引:10,自引:0,他引:10
采用焙烧前驱物碱式碳酸锌的方法制备了不同粒径的ZnO纳米粒子,而用粒径 最小的作为光催化剂,通过光还原过程分别得了贵金属质量分数为0.5%和0.75%的 Pd/ZnO或Ag/ZnO复合纳米粒子。利用XRD,TEM,XPS,SPS和EFISPS等测试技术对样 品进行了表征,并通过光催化氧化气相正庚烷评估了样品的光催化活性,考察了微 晶尺寸和贵金属Pd或Ag的沉积对ZnO纳米粒子表面光电压信号以及光催化活性的影 响,探讨了样品表面光电压谱与其光催化活性的关系,说明了可以通过表面光电压 谱的测试来初步地评估纳米粒子的光催化活性。结果表明:随着ZnO纳米微晶尺寸 的减小,其SPS信号强度逐渐变弱,而光催化活性逐渐升高;沉积适量的贵金属Pd 或Ag后,ZnO纳米粒子的SPS信号强度明显下降,而其光催化活性却有所升高。此外 ,对ZnO纳米粒子光催化剂的失活机理进行了分析。 相似文献
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ZnO纳米粒子的表面光电压谱和光催化性能 总被引:3,自引:0,他引:3
采用焙烧前驱物碱式碳酸锌的方法制备了不同粒径的ZnO纳米粒子,而用粒径 最小的作为光催化剂,通过光还原过程分别得了贵金属质量分数为0.5%和0.75%的 Pd/ZnO或Ag/ZnO复合纳米粒子。利用XRD,TEM,XPS,SPS和EFISPS等测试技术对样 品进行了表征,并通过光催化氧化气相正庚烷评估了样品的光催化活性,考察了微 晶尺寸和贵金属Pd或Ag的沉积对ZnO纳米粒子表面光电压信号以及光催化活性的影 响,探讨了样品表面光电压谱与其光催化活性的关系,说明了可以通过表面光电压 谱的测试来初步地评估纳米粒子的光催化活性。结果表明:随着ZnO纳米微晶尺寸 的减小,其SPS信号强度逐渐变弱,而光催化活性逐渐升高;沉积适量的贵金属Pd 或Ag后,ZnO纳米粒子的SPS信号强度明显下降,而其光催化活性却有所升高。此外 ,对ZnO纳米粒子光催化剂的失活机理进行了分析。 相似文献
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纳米Ag/ZnO光催化剂及其催化降解壬基酚聚氧乙烯醚性能 总被引:4,自引:0,他引:4
采用氨浸法制备了不同Ag负载量的纳米Ag/ZnO光催化剂,并用X射线衍射、比表面积测定、X射线光电子能谱和漫反射紫外-可见光谱测定了Ag/ZnO的晶型结构、比表面积、表面组成和光谱特征.以壬基酚聚氧乙烯醚(NPE-10)为模型污染物,分别在紫外光和可见光照射下考察了纳米Ag/ZnO的光催化活性.结果表明,Ag能成功地负载到ZnO表面,且随着Ag负载量的增加,ZnO的粒径逐渐增大,比表面积逐渐减小.与纳米ZnO样品相比,Ag/ZnO中Ag 3d5/2结合能减小,而Zn 2p和O 1s结合能增大,ZnO表面的羟基氧和吸附氧含量增加.当Ag负载量大于0.5%时,Ag/ZnO样品的吸收光谱发生红移,在可见光区出现吸收.光催化降解结果表明,0.5%Ag/ZnO样品的光催化活性最高,在紫外光和可见光照射3 h后NPE-10降解率分别约为77%和56%,而ZnO样品的光催化活性仅约为61%和40%. 相似文献
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ZnO超微粒子光催化氧化降解n-C7H16的研究 总被引:8,自引:0,他引:8
利用ZnO光催化氧化技术对气相n-C7H16进行了降解研究,考察了氧气、水燕气体积分数等因素对n-C7H16光催化氧化的影响,利用气相色谱-质谱联用仪和气相色谱仪对气相光催化反应过程中的气体组成进行了定性分析,并对主要中间产物丙醛进行了定量分析,结果发现,ZnO超微粒子光催化氧化n-C7H16的降解率较高,n-C7H16绝大部分被完全氧化成CO2,探讨了n-C7H16光催化氧化反尖的动力学行为及机理。 相似文献
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Uroš Grošelj Mojca Žorž Amalija Golobič Branko Stanovnik Jurij Svete 《Tetrahedron》2013,69(52):11092-11108
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives. 相似文献
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The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion. 相似文献
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N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%). 相似文献
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Shashikant U. Dighe Surya K. Samanta Shivalinga Kolle Sanjay Batra 《Tetrahedron》2017,73(17):2455-2467
An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y1 and Y2. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones. 相似文献
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In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates. 相似文献
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Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described. 相似文献
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An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions. 相似文献
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Jona Mirnik Eva Pušavec Kirar Sebastijan Ričko Uroš Grošelj Amalija Golobič Franc Požgan Bogdan Štefane Jurij Svete 《Tetrahedron》2017,73(24):3329-3337
A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu0 as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than CuI in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT). 相似文献
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George E. Magoulas Thomas Garnelis Constantinos M. Athanassopoulos Dionissios Papaioannou George Mattheolabakis Konstantinos Avgoustakis Dimitra Hadjipavlou-Litina 《Tetrahedron》2012,68(35):7041-7049
(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C60, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine. 相似文献