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YingMei Xie Lu Lv MingHui Li BingCai Pan Qun Chen WeiMing Zhang QuanXing Zhang 《中国科学:化学(英文版)》2012,55(3):409-415
A new polymeric nanocomposite photocatalyst A15-CdS with large spherical beads (0.70-0.80 mm in diameter) was fabricated for efficient Rhodamine B (RhB) photodegradation with facile separation during cyclic runs,and photocorrosion,a congenital drawback of CdS,was successfully inhibited for A15-CdS.The nanocomposite catalyst was obtained by impregnating CdS nanoparticles within porous polymeric cation exchanger A15 through a facile inner-surface deposition.CdS nanoparticles (<20 nm) immobilized in A15 were deliberately distributed within an outside ring-like region of 40-50 m in depth,which is dominant for photoreaction because visible light is not expected to permeate through the inner region of nontransparent A15.As expected,efficient RhB photodegradation by A15-CdS was achieved under visible light irradiation,and large-size A15-CdS beads are expected to result in their facile separation from solution for repeated use.More significantly,negligible photocorrosion for the hybrid catalyst A15-CdS was demonstrated by the constant photodegradation efficiency and negligible CdS loss during five-cycle runs.The results indicated that nano-CdS immobilization within A15 would greatly improve the applicability of CdS nanoparticles in practical environmental remediation. 相似文献
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以LaNiO_3纳米颗粒为基质,在水热法制备CdS的过程中引入Mn~(2+)离子,原位合成直接Z型LaNiO_3/Mn_(0.2)Cd_(0.8)S异质结光催化剂。分别采用场发射扫描电镜、X射线衍射、X射线光电子能谱、紫外可见漫反射光谱、氮气吸附-脱附测试以及电化学测试等分析方法对制备的催化剂进行表征。在光解水产氢测试中,LaNiO_3/Mn_(0.2)Cd_(0.8)S异质结光催化剂在5 h的H_2产量达到1 190.3μmol,相较于CdS和Mn_(0.2)Cd_(0.8)S,其H_2产量分别提高了 25倍和10倍。荧光和电化学实验证实,Mn~(2+)的引入能够有效地促进光生载流子的分离,同时LaNiO_3/Mn_(0.2)Cd_(0.8)S之间异质结的构筑能有效地促进光生载流子在界面间的迁移、分离,从而促进其光解水产氢效率和稳定性的提高。结合一系列表征和活性测试结果提出直接Z型光解水反应机理,很好地阐述了其光解水产氢活性和稳定性的增强。 相似文献
3.
Effect of Controlled Deposition of ZnS Shell on the Photostability of CdTe Quantum Dots as Studied by Conventional Fluorescence and FCS Techniques
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The effect of one and two monolayers of ZnS shells on the photostability of CdTe quantum dots (QDs) in aqueous and nonaqueous media has been studied by monitoring the fluorescence behavior of the QDs under ensemble and single‐molecule conditions. ZnS capping of the CdTe QDs leads to significant enhancement of the fluorescence brightness of these QDs. Considerable enhancement of the photostability of the shell‐protected QDs, including the suppression of photoactivation, is also observed. Fluorescence correlation spectroscopy measurements reveal an increase in the number of particles undergoing reversible fluorescent on–off transitions in the volume under observation with increasing excitation power; this effect is found to be more pronounced in the case of core‐only QDs than for core–shell QDs. 相似文献
4.
V. V. Shvalagin A. L. Stroyuk S. Ya. Kuchmii 《Theoretical and Experimental Chemistry》2004,40(6):378-382
Cathodic photocorrosion occurs upon stationary photoirradiation of ethanolic ZnO sols. The photocorrosion rate increases with decreasing particle size. This effect due to the appearance of quantum-sized effects in ZnO nanocrystals results from an increase in the reduction potential of the semiconductor upon irradiation, which may exceed the Fermi level for cathodic decomposition of zinc oxide nanoparticles.Translated from Teoreticheskaya i Éksperimentalnaya Khimiya, Vol.40, No.6, pp. 363–367, November–December, 2004. 相似文献
5.
利用Cd(OH)_2选择性包覆与光分解腐蚀缩小CdS纳米微粒的尺寸分布的研究 总被引:1,自引:0,他引:1
提出结合Cd(OH)2 选择性包覆与光分解腐蚀法缩小CdS纳米微粒的尺寸分布, 并通过对CdS纳米微粒发射光谱的研究证实了这一设计思想. 以多聚磷酸钠(HMP)为稳定剂合成CdS纳米微粒, 再通过Cd2+ 与OH- 的选择性包覆在大粒径的CdS纳米微粒表面形成一层Cd(OH)2, 然后溶液置于日光下辐照处理, 数天后, 未经包覆的小粒径CdS纳米微粒被日光腐蚀分解, 溶液中只剩下被Cd(OH)2 包覆的大粒径CdS纳米微粒, 这样即可达到缩小CdS纳米微粒尺寸分布的目的. 相似文献
6.
不同形貌Cu_xCd_(1-x)S光催化剂光腐蚀性能差异研究 总被引:1,自引:0,他引:1
利用溶剂热法和水热法,合成出不同形貌的CuxCd1-xS光催化剂,并考察了它们的抗光腐蚀性能。荧光实验表明适量的铜掺杂取代后得到的CuxCd1-xS晶体具有良好的光生电子-空穴对的分离性能,有利于光生载流子的快速转移;不同形貌是导致样品抗光腐蚀性能不同的重要原因;此外铜掺杂量和晶体结晶度都对催化剂光腐蚀性能有重要影响。 相似文献
7.
V. V. Shvalagin A. E. Raevskaya A. L. Stroyuk S. Ya. Kuchmii 《Theoretical and Experimental Chemistry》2007,43(3):184-190
The possibility of decreasing the size of colloidal nanoparticles of CdS in the oxidative photocorrosion reaction in the presence
of methylviologen and of increasing their size during photocatalytic reduction of sulfur in ethanol in the presence of cadmium
acetate. A dependence of the quantum yield of the latter reaction on the initial size of CdS nanoparticles was observed, which
was interpreted as a result of quantum size effects.
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Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 3, pp. 170–175, May–June, 2007. 相似文献
8.
Photoelectrochemical corrosion of n-type α-PbO electrodes in aqueous Fe(CN)6
3−/4− and I−/I3
− electrolytes using the rotating ring-disk electrode technique has been investigated. The α-PbO thin film is found to be more
stable in I−/I3
− (48%) than in Fe(CN)6
3−/4− electrolyte (10%). Preferential adsorption of iodide ions decreases the photocorrosion reaction of holes with α-PbO. Addition
of CsI (0.4 mM) to the I−/I3
− electrolyte decreases the photocorrosion from 48% to less than 10%. Cs+ ions perhaps nullify the effect of negatively charged surface states of α-PbO, thus minimizing the trapping of holes at the
surface of α-PbO and hence decrease the possibility of photocorrosion of lead oxide with holes.
Received: 30 June 1998 / Accepted: 20 April 1999 相似文献
9.
采用NaBH_4还原法合成了系列Pt沉积的Ag_2CO_3复合光催化剂。通过在可见光照射下降解甲基橙研究沉积不同含量的Pt对Ag_2CO_3光催化性能的影响。应用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、透射电镜(TEM)、光电子能谱(XPS)、傅立叶变换红外光谱(FT-IR)、光致发光光谱(PL)、紫外可见漫反射吸收光谱(DRS)、光电流(PC)和N_2物理吸附等研究了沉积Pt纳米颗粒对Ag_2CO_3纳米晶的物理化学性质的影响。结果表明,沉积质量分数为0.1%~0.5%的Pt,可使Ag_2CO_3的活性提升3倍以上,同时光催化剂的稳定性得到极大改善。Pt/Ag_2CO_3光催化性能大幅提升的主要原因是,沉积少量的Pt可以增强Ag_2CO_3对可见光的吸收,同时增大Ag_2CO_3的比表面积和表面羟基的数量;另外,沉积在Ag_2CO_3表面的Pt粒子可以承担电子俘获中心的作用,使Ag_2CO_3中光激发产生的电子(e~-)有效地转移到Pt上,加速光生电子-空穴对的分离速率,产生更多的光催化活性自由基,在提升光催化活性的同时,减少Ag_2CO_3中的Ag~+被光生电子(e~-)还原的几率,增强Ag_2CO_3的抗光腐蚀能力。 相似文献
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