JOURNAL OF MATERIALS RESEARCH
·
2016
·Vol. 31
·期 4
·468-479
·
IF 1.579
Zhijun Wei,Lingjie Zhang,Hui Yang,Tao Shen,Lawson Chen
Two kinds of Ag/ZnO electrical contact materials were fabricated by powder metallurgy method. The electrical life testing was done to investigate the arc erosion behavior of the prepared contact materials. Their properties and morphologies were characterized and discussed in detail. Results showed that Ag/ZnO(c) with coprecipitated ZnO as the second phase had better mechanical and electrical properties compared with Ag/ZnO(a) with ZnO purchased from Aladdin Industrial, Inc. Besides, some typical morphologies, such as holes, Ag or ZnO enrichment zone, Ag skeletons and bubbling area, occurred on the surface of the contacts. Especially for Ag/ZnO(c), vertically aligned ZnO nanorod arrays were detected after the life testing without any other supporting equipment. The existence of a solid solution Zn1−x
Ag
x
O and different energy generated during arcing process were possible reasons resulting in this phenomenon. A solid–vapor–solid mechanism was put forward to analyze the phenomenon mentioned above. These evidences could also offer some valuable information desired for reducing the splashing of Ag droplet under arcing.
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Methods and Applications in Fluorescence
·
2017
·Vol. 5
·期 2
·024010
·
IF 2.656
Lu He,Lin Yang,Hao Zhu,Wenkui Dong,Yujie Ding,Jun-Jie Zhu
A novel luminescence 'Turn-On' nanoplatform for the sensitive sensing of Ag+ was fabricated based on luminescence resonance energy transfer technique between sodium citrate functionalized upconversion nanoparticles (Cit-UCNPs, energy donor) and graphene quantum dots (GQDs, energy acceptor). Amino-labeled single-stranded DNA (NH2-ssDNA) containing a number of cytosine (C) was conjugated on the surface of the Cit-UCNPs to capture Ag+ ions. Due to the π–π stacking interaction between NH2-ssDNA and GQDs, the upconversion luminescence can be quenched. However, upon the addition of Ag+, the π–π stacking interaction weakens due to the formation of the hairpin structure of C–Ag+–C on the UCNPs. As a result, GQDs will leave the surface of the UCNPs and the upconversion luminescence can be enhanced (Turn-On). Based on this fact, the sensor was developed for the detection of Ag+ with a linear concentration range from 2 × 10−4 to 1 μM and a detection limit as low as 60 pM. The assay method is fairly simple with high selectivity and sensitivity, which can be used for the determination of Ag+ in environmental water samples.
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CHEMICAL ENGINEERING JOURNAL
·
2016
·
IF 5.31
Lei Wang,Changbo Zhang,Feng Gao,Gilles Mailhot,Gang Pan
Algae as an abundant natural biomass, more attention has been paid to explore its potential application in environmental pollutants treatment. This work prepared the algae-TiO 2 /Ag bionano hybrid material by loading algae cells on the ultrafine TiO 2 /Ag chitosan hybrid nanofiber mat. For the first time, the synergistic photocatalytic effect of fresh algae and TiO 2 /Ag nanomaterial was investigated by removal of Cr(VI). The addition of algae significantly improved the photo-removal of Cr(VI) in the system with TiO 2 /Ag hybrid nanomaterial under visible light irradiation. Meanwhile, the photocatalytic mechanism was studied. The photogenerated reactive oxygen species were quantified and the addition of algae apparently decreased the yields of OH to 31.0 μM, while improved the yields of 1 O 2 and O 2 − in the reaction system with TiO 2 /Ag hybrid nanofiber mats. The change of superoxide dismutase activity and malondialdehyde content in algae indicated that TiO 2 /Ag could impose oxidative stress and cause lipid peroxidation in algae cells. During the course of irradiation, algae released substances could act as scavenger for holes, thus inhibited the recombination of hole/electron and enhanced the photocatalytic reduction of Cr(VI) by electrons on TiO 2 surface. Algae was simultaneously photodegraded in the system and the resulting O 2 − , organic free radicals could promote the reduction of Cr(VI). This functional hybrid nanofiber mat was easily recovered and maintained a great photocatalytic activity on the five successive cycles. This algae-photocatalyst hybrid material has promising applications potential in heavy metal removal and organic pollutants treatment.
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APPLIED SURFACE SCIENCE
·
2016
·
IF 3.15
Zhi Zhu,Xu Tang,Changchang Ma,Minshan Song,Nailing Gao,Youshan Wang,Pengwei Huo,Ziyang Lu,Yongsheng Yan
The ternary conductive Ppy@Ag/g-C 3 N 4 composite photocatalysts was successfully synthesized by polymerization process and surface polymerization technique. And the as-prepared Ppy@Ag/g-C 3 N 4 sample exhibited the higher photocatalytic activity for various pollutant (MO, DM, TC, CIP, GFLX and EH) remove than that of pure g-C 3 N 4 and Ag/g-C 3 N 4 under visible light irradiation. It mainly originated from the Ag nanoparticles anchored between g-C 3 N 4 and Ppy acted as electron transfer mediator that facilitated the charge carrier separation and then expending the lifetime of the carriers. Meanwhile, the obtained Ppy@Ag/g-C 3 N 4 sample also showed a relatively good recycling stability which was the crucial factor for photocatalyst practical application. This work provided a new facile strategy for improving photo-degradation activity of g-C 3 N 4 photocatalyst.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2017
·
IF 3.133
Qiqi Nie,Yongbo Wang,Licong Jia,Bei Liu,Enzhou Liu,Xiaoyun Hu,Jun Fan
In this paper, a novel detection method based on luminescence resonance energy transfer (LRET) system for sensitive detection of Mn 2+ ions has been proposed. The positively charged upconversion nanoparticles capped with polyethyleneimin (PEI-UCNPs) and negatively charged Ag NPs capped with tripolyphosphate (P 3 O 10 5− -Ag NPs) were bound through electrostatic interaction . They were used as energy donors and acceptors, respectively. The green upconversion luminescence could be quenched because of a good overlap between the UCNPs emission and the Ag NPs absorption spectra . Nevertheless, the LRET was disrupted and the green upconversion luminescence was restored in the presence of Mn 2+ because of the coagulation of P 3 O 10 5− -Ag NPs. Thus, the relative luminescence intensity increased as the concentrations of Mn 2+ increased. The response is linear to the concentrations of Mn 2+ in the range from 0.2 to 5 μM, and the detection limit is evaluated to be 150 nM (S/N = 3). This probe was easy to operate with satisfactory selectivity and excellent sensitivity, which would be able to satisfy the requirements of Mn 2+ -related detection.
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BIOSENSORS & BIOELECTRONICS
·
2016
·
IF 7.476
Ling Zhang,Yue Sun,Yan-Yu Liang,Jian-Ping He,Wei-Wei Zhao,Jing-Juan Xu,Hong-Yuan Chen
Herein the influence of ultrasmall Ag nanoclusters (Ag NCs) against CdS quantum dots (QDs) in a photoelectrochemical (PEC) nanosystem was exploited for the first time, based on which a novel PEC bioanalysis was successfully developed via the efficient quenching effect of Ag NCs against the CdS QDs. In a model system, DNA assay was achieved by using molecular beacon (MB) probes anchored on a CdS QDs modified electrode , and the MB probes contain two segments that can hybridize with both target DNA sequence and the label of DNA encapsulated Ag NCs. After the MB probe was unfolded by the target DNA sequence, the labels of oligonucleotide encapsulated Ag NCs would be brought in close proximity to the CdS QDs electrode surface , and efficient photocurrent quenching of QDs could be resulted from an energy transfer process that originated from NCs. Thus, by monitoring the attenuation in the photocurrent signal, an elegant and sensitive PEC DNA bioanalysis could be accomplished. The developed biosensor displayed a linear range from 1.0 pM to 10 nM and the detection limit was experimentally found to be of 0.3 pM. This work presents a feasible signaling principle that could act as a common basis for general PEC bioanalysis development.
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RSC Advances
·
2016
·Vol. 6
·期 63
·58113-58117
·
IF 3.289
Guangguang Huang,Chunlei Wang,Xiaojing Xu,Yiping Cui
We reported an optical ratiometric temperature sensor via dopant-dependent dual emissions in Ag&Mn:ZnInS QDs. For QDs, the Ag-related emission is around 485 nm arising from the radiative recombination of the captured electrons' anion vacancies with holes trapped at the Ag dopant level. The energy level of anion vacancies is just below the conduction band, which can attain thermal equilibrium easily without further energy level adjusting. Moreover, Mn-related emission is around 585 nm via the Mn2+ ligand-field transition from 4T1 to 6A1. Mn-related thermal equilibrium is effectively suppressed due to the large energy gap between the conduction band and 4T1 energy level. These features not only obtain the opportunity to use the photoluminescence temperature specificity of Ag and Mn for ratiometric temperature sensing, but also make the flash synthetic approach via a pot non-injection possible. This temperature sensor, designed with Ag&Mn:ZnInS QDs, exhibits good temperature sensitivity (∼0.227% °C−1) and high QY (20%).
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ENVIRONMENTAL POLLUTION
·
2017
·
IF 5.099
Yongguang Yin,Dan Han,Chao Tai,Zhiqiang Tan,Xiaoxia Zhou,Sujuan Yu,Jingfu Liu,Guibin Jiang
Photo-reduction of Ag + to silver nanoparticle (AgNPs) by dissolved organic matter (DOM) is a possible source of naturally occurring AgNPs. However, how this photo-reduction process is influenced by ubiquitous metal ions is still not well understood. In addition, in previous studies, the formation of AgNPs in DOM solution was usually monitored by UV-Vis spectroscopy, and there is still lack of quantitative analysis for the formed AgNPs. In the present study, the role of Fe 2+ /Fe 3+ at environmental concentration level on this photochemical process was investigated, and the enhanced formation of AgNPs by Fe 2+ /Fe 3+ was probed and quantified by using UV-Vis spectroscopy, transmission electron microscopy , and liquid chromatography-inductively coupled plasma mass spectrometry. It was demonstrated that while Fe 3+ can oxidize AgNPs to release Ag + , Fe 2+ can reduce Ag + into AgNPs. However, the DOM-induced reduction of Fe 3+ makes iron an effective electron shuttle between DOM and Ag + , and both Fe 2+ and Fe 3+ enhanced AgNP formation. The impacts of environmentally relevant factors, including DOM concentration and solution pH, on this process were studied comprehensively, which showed that the catalytic role of iron was more significant at higher DOM concentration and lower pH. This iron-enhanced formation of AgNPs in photo-irradiated Ag + -DOM solution have great environmental implications on the formation of natural AgNPs and the transformation of engineered AgNPs in acidic surface water with high iron content.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2017
·
IF 9.446
Chenxi Zhang,Kai Yu,Yajun Feng,Yue Chang,Ting Yang,Ying Xuan,Da Lei,Lan-Lan Lou,Shuangxi Liu
The novel visible-light-driven 3DOM-SrTiO 3 /Ag/Ag 3 PO 4 ternary composites were fabricated and used as photocatalysts in the degradation of organic contaminants, including RhB, phenol , and MB. Through the XRD, SEM, TEM, DR UV–vis, XPS, PL spectroscopy, N 2 sorption , and photoelectrochemical measurement, the obtained 3DOM-SrTiO 3 /Ag/Ag 3 PO 4 ternary composites were well characterized. The effects of SrTiO 3 :Ag 3 PO 4 molar ratio and stop-bands of 3DOM-SrTiO 3 on the catalytic performance were systemically investigated. 3DOM-SrTiO 3 /Ag/Ag 3 PO 4 ternary composite photocatalysts exhibited notably enhanced activity compared with single 3DOM-SrTiO 3 and Ag 3 PO 4 catalyst. Among these ternary photocatalysts, S35A65(300) exhibited the most excellent photocatalytic performance under visible light irradiation, which could be mainly attributed to synergy effect of the notably improved separate efficiency of photogenerated electron-hole pairs and the suitable stop-bands of 3DOM-SrTiO 3 (300) material. Although the gradually reduced activity in cycling tests was obtained over S35A65(300) under visible light irradiation, an excellent durability could be achieved for S35A65(300) under UV–vis light irradiation. No obvious loss in photocatalytic efficiency was observed after six cycles for RhB degradation. The notably improved enhanced durability of 3DOM-SrTiO 3 /Ag/Ag 3 PO 4 ternary composites under UV–vis light irradiation could be mainly attributed to the Z-scheme mechanism of this ternary composite photocatalyst.
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BIORESOURCE TECHNOLOGY
·
2017
·
IF 5.651
Zheng-Zhe Zhang,Jia-Jia Xu,Zhi-Jian Shi,Ya-Fei Cheng,Zheng-Quan Ji,Rui Deng,Ren-Cun Jin
The increasing application of engineered nanoparticles (NPs) has posed an emerging challenge to wastewater treatment processes. The short-term impacts of CuNPs, CuONPs, ZnONPs and AgNPs on anaerobic ammonium oxidation (anammox) process were investigated firstly in this study. CuONPs, ZnONPs and AgNPs up to 50 mg g −1 suspended solid (SS) did not affect anammox activity, reactive oxygen species (ROS) production or cell membrane integrity. However, 1.25 mg g −1 SS CuNPs significantly inhibited the anammox activity and the loads that caused 50% inhibition were 4.64 ± 1.24 and 3.27 ± 0.79 mg g −1 SS for anammox granules and flocs, respectively. 5 mg g −1 SS CuNPs caused serious accumulation of the toxic intermediate N 2 H 4 . Furthermore, CuNPs interacted with extracellular polymeric substances by specifically bonding to tyrosine or tryptophan-containing groups, C-O-C in polysaccharides and –OH in polymeric compounds. Therefore, this study calls for more attention to the risks of NPs to the anammox-based processes.
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Nanoscale Research Letters
·
2017
·Vol. 12
·期 1
·1-10
·
IF 2.833
Qin Yanyan,Cui Yanping,Tian Zhen,Wu Yangling,Li Yilian
Ag@AgCl core–shell nanowires were synthesized by oxidation of Ag nanowires with moderate FeCl 3 , which exhibited excellent photocatalytic activity for As(III) oxidation under visible light. It was proved that the photocatalytic oxidation efficiency was significantly dependent on the mole ratio of Ag:AgCl. The oxidation rate of As(III) over Ag@AgCl core–shell nanowires first increased with the decrease of Ag 0 percentage, up until the optimized synthesis mole ratio of Ag nanowires:FeCl 3 was 2.32:2.20, with 0.023 mg L −1 min −1 As(III) oxidation rate; subsequently, the oxidation rate dropped with the further decrease of Ag 0 percentage. Effects of the pH, ionic strength, and concentration of humic acid on Ag@AgCl photocatalytic ability were also studied. Trapping experiments using radical scavengers confirmed that h + and ·O 2
− acted as the main active species during the visible-light-driven photocatalytic process for As(III) oxidation. The recycling experiments validated that Ag@AgCl core–shell nanowires were a kind of efficient and stable photocatalyst for As(III) oxidation under visible-light irradiation.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2016
·
IF 3.014
Jiajia Tao,Zezhou Gong,Guang Yao,Yunlang Cheng,Miao Zhang,Jianguo Lv,Shiwei Shi,Gang He,Xiaoshuang Chen,Zhaoqi Sun
TiO 2 nanorod arrays (NRAs) were hydrothermally grown on transparent fluorine-doped tin oxide (FTO) substrates, and were converted into nanotubes (NTAs) by hydrothermally in situ etching. Ag nanoparticles (NPLs) were sensitized on the NRAs and NTAs by a simple photodeposition approach (products were denoted as Ag-TiO 2 NRAs and NTAs). The Ag-TiO 2 NTAs samples possessed a large specific surface area (116 m 2 g -1 ) with Ag NPLs homogeneously dispersed among the TiO 2 NTAs. The Ag-TiO 2 NTAs exhibited significantly enhanced photocatalytic activities (98.8%) in degradation of methyl orange (MO) compared to Ag-TiO 2 NRAs (92.6%), TiO 2 NTAs (86.2%), and NRAs (81.7%). The enhanced photocatalytic activities can be attributed to the large specific surface area of TiO 2 NTAs and strong surface plasmon resonance (SPR) of Ag NPLs. In addition, Ag-TiO 2 NTAs showed easy recovery feature in the recovery process and high durability in the recycling test, which was expected to be an efficient and practical photocatalyst used for waste water treatment.
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