Nanoscale
·
2019
·Vol. 12
·期 7
·4359-4365
·
IF 6.97
Zhen Wang,Chunxue Zheng,Peng Zhang,Zhulin Huang,Chuhong Zhu,Xiujuan Wang,Xiaoye Hu,Jian Yan
Herein, we report a facile strategy of combined SERS measurements based on a split-type SERS substrate, which exhibits excellent SERS activity, detection signal reproducibility and chemical stability. The SERS substrate consists of an ordered Al2O3@Ag@Si nanocone array and Ag nanoparticles (Ag-NPs), both of which are fabricated individually. The Al2O3@Ag@Si nanocone array is obtained by ion-sputtering Ag on an Si nanocone array and then coating an ultrathin (∼2 nm) Al2O3 dielectric layer via atomic layer deposition (ALD). Ag-NPs are synthesized via the liquid phase method and then immersed in an organic solvent for liquid seal. For the SERS measurement, Ag-NPs are dispersed in a liquid containing the probe molecules and then, they self-assemble on the surface of the Al2O3@Ag@Si nanocones. Subsequently, the ultrathin Al2O3 dielectric layer separates Ag-NPs from the Ag@Si nanocones, forming massive gap-introduced hot spots. This substrate is sensitive to 1 pM Rhodamine R6G with an average enhancement factor of up to 109, exhibiting excellent SERS activity. Moreover, due to the protection of the Al2O3 dielectric layer and the organic solvent for the Ag@Si nanocones and Ag-NPs against oxidation, the split-type SERS substrate achieves an SERS signal with almost no attenuation after five months, indicating its good chemical stability.
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SENSORS AND ACTUATORS B-CHEMICAL
·
2019
·
IF 6.393
Han Lu,Mingliang Jin,Qilin Ma,Zhibin Yan,Zhenping Liu,Xin Wang,Eser Metin Akinoglu,Albert van den Berg,Guofu Zhou,Lingling Shui
In this work, we report a quick and controllable method for fabricating Ag nanoparticles (NPs) and nano-assemblies (NAs) on silicon (Si) surface via a galvanic reaction assisted by surfactant hexadecyltrimethylammonium bromide (CTAB). Obtained Si substrates with high density Ag NAs serve as surface-enhanced Raman scattering (SERS) substrates for unlabelled molecular sensing. The addition of CTAB enables not only the electromagnetic enhancement by controllable producing Ag NAs “hotspots”, but also the signal enhancement by enriching probe molecules via hydrophobic interaction. Two concentration regimes of 1.0 × 10 −8 –1.0 × 10 −11 M and 1.0 × 10 −12 –1.0 × 10 −16 M have been obtained for quantitative and qualitative detection of Rhodamine 6G (R6G) in aqueous solution, respectively. As a result, for determination of R6G, the quantitative and qualitative detection limits of 1.0 × 10 −11 and 1.0 × 10 −16 M have been obtained, respectively, with high reproducibility showing the relative standard deviation (RSD) of ∼7.3%. Simulation has been carried out using finite-difference time-domain (FDTD) to evaluate the dependence of electric field on the size and inter-gap of Ag NPs, showing good agreement with experimental results. The high sensitivity also enables SERS characterization of non-resonant and low Raman cross-section biomolecules, for example, amino acids. Such a fabrication process is simple, fast, cheap and reproducible; and therefore, it would be helpful to produce high sensitive SERS substrates to broaden their applications in chemical and biological fields for molecular diagnostics to single-/multiple-molecule detection.
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JOURNAL OF MEMBRANE SCIENCE
·
2023
·
IF 9.5
Hailan Wang,Ya Xu,Bozhan Ma,Wenxuan Zou,Jin Zeng,Ruobin Dai,Zhiwei Wang
Environmental and economic concerns necessitate the recycle of end-of-life (EOL) reverse osmosis (RO) membranes. Controlled downcycling of EOL RO membrane to nanofiltration (NF)-like or ultrafiltration (UF)-like membrane through regulating sodium hypochlorite (NaClO) exposure doses has been developed in recent years. However, the impact of foulants on the chlorination-based membrane downcycling is often overlooked. An alkaline-NaClO treatment strategy was employed to downcycle Si-Al complex-fouled EOL RO membrane. Alkaline cleaning not only partially removed Si-Al complex foulants via dissolution, but also converted Al 2 O 3 ·SiO 2 to Al-O-Si amorphous oxides . Subsequent NaClO treatment gradually deconstructed the Si-Al complex fouling layer by dissolving Al contained in Al-O-Si amorphous oxides and degraded the polyamide (PA) layer with extended exposure time, resulting in membrane with loose NF-like characteristic. Moreover, the conversion of Al-contained component with alkaline pre-treatment prevented Al 3+ -catalyzed degradation of PA layer and ensure controlled downcycling. For the downcycling to UF-like membrane, complete removal of PA layer with sufficient chlorine oxidation was essential while alkaline pre-treatment process was optional. Both downcycled loose NF-like and UF-like membranes exhibited satisfactory filtration and antifouling performance. Our study presents an effective and robust protocol for controllable downcycling of EOL RO membrane with alkaline pre-treatment based on their fouling characteristic.
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MICROPOROUS AND MESOPOROUS MATERIALS
·
2023
·
IF 5.2
Rui-Li Yu,Qian-Fan Li,Hao-Ran Sun,Zhen-Le Li,Liang-Zhi Xia
In order to efficiently and rapidly capture radioactive iodine that impacts the environment, this study involves impregnating Tetraethylenepentamine (TEPA) into ZSM-5 zeolite with varying Si/Al ratios and evaluating its adsorption performance towards iodine. It is found that the optimal preparation level is 30 %, leading to a significant increase in the saturated adsorption capacity compared to non-impregnated molecular sieves , with a four-fold improvement. The adsorption rate is also enhanced. Various amines are utilized for impregnation, and FT-IR and molecular computation techniques are employed to investigate the adsorption mechanisms between these amines and iodine. The discovery reveals potential interactions between the amine groups and iodine, such as N ⋅ ⋅ ⋅ I halogen bonding and N–H ⋅ ⋅ ⋅ I hydrogen bonding . These findings provide valuable insights for developing iodine adsorbents, offering promising solutions for protecting ecological and living environments.
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Analytical Methods
·
2023
·Vol. 15
·期 37
·4851-4861
·
IF 3.1
Rui Yang,Baowen Zhang,Ya Wang,Yi Zheng,Qian Zhang,Xiupei Yang
Substrate materials with high sensitivity and storage stability are crucial for the practical analytical application of surface-enhanced Raman scattering (SERS) techniques. In this work, a SERS-active substrate (Si/Au@Ag/ZIF-67) was fabricated with a metal–organic framework (ZIF-67) on a plasmonic surface (Si/Au@Ag) via self-assembly. The as-prepared material combined the properties of the abundant hotspots of the Au@Ag nanoparticles and the excellent adsorption performance of ZIF-67 for organic molecules. The synergy leads to high sensitivity of the composite substrate with a low detection limit for 4-aminothiophenol (a typical Raman reporter molecule) down to 2.0 × 10−9 M and the analytical enhancement factor (AEF) of the SERS substrate is 3.4 × 106. Moreover, the substrates exhibited good repeatability, high reproducibility, and reliable stability due to the MOF coating. The SERS signal was stable after 60 days of storage at room temperature. Ultimately, the optimal Si/Au@Ag/ZIF-67 was applied as a SERS sensor to analyze thiram, and the results showed a linear concentration range from 10−7 to 10−5 M with good linearity (R2 = 0.9934). The recoveries of thiram in spiked apple juice were in the range of 95.7–102.3%, with relative standard deviations less than 4.3%. These results predict that the proposed SERS substrates may hold great potential for the detection of environmental and food pollution in practical applications.
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International Journal of Minerals Metallurgy and Materials
·
2023
·Vol. 30
·期 9
·1705-1715
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IF 4.8
Zhou Guotao,Wang Yilin,Qi Tiangui,Zhou Qiusheng,Liu Guihua,Peng Zhihong,Li Xiaobin
Goethitic bauxite is a widely used raw material in the alumina industry. It is an essential prerequisite to clarify the effect of Ti- and Si-containing minerals on goethite transformation in the Bayer digestion process, which could efficiently utilize the Fe- and Al-containing minerals present in goethitic bauxite. In this work, the interactions between anatase or kaolinite with goethite during various Bayer digestion processes were investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The results showed that anatase and kaolinite hindered the transformation of goethite. Anatase exerted more significant effects than kaolinite due to the dense sodium titanate layer on the goethite surface after reacting with the sodium aluminate solution. Adding the reductant hydrazine hydrate could eliminate the retarding effect by inducing the transformation of goethite into magnetite. In this process, titanium was embedded into the magnetite lattice to form Ti-containing magnetite. Furthermore, the weakening of the interaction between magnetite and sodium aluminosilicate hydrate reduced the influence of kaolinite. As a validation of the above results, the reductive Bayer method resulted in the transformation of goethite into goethitic bauxite with 98.87% relative alumina digestion rate. The obtained red mud with 72.99wt% Fe 2 O 3 could be further utilized in the steel industry. This work provides a clear understanding of the transformative effects of Ti- and Si-containing minerals on iron mineral transformation and aids the comprehensive use of iron and aluminum in goethitic bauxite subjected to the reductive Bayer method.
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CATALYSIS TODAY
·
2019
·
IF 4.888
Yiwen Jiang,Ling Zhang,Yiquan Xie,Shichao Han,Qiuyan Zhu,Xiangju Meng,Feng-Shou Xiao
A series of zeolite-supported Pt nanoparticles (Pt/NaZSM-5) have been prepared by adjusting Si/Al ratio of NaZSM-5 zeolite from 60 to pure silica. Catalytic tests in propene oxidation as an important model reaction for removal of hydrocarbons emitted from automobiles during cold-start, show that the catalytic activities significantly increase with Si/Al ratios of NaZSM-5 zeolite in these Pt/NaZSM-5 catalysts. As a typical example, Silicalite-1 supported Pt nanoparticles exhibits the highest activity, giving the 50% conversion temperature (T 50 ) and 90% conversion temperature (T 90 ) at 112 °C and 118 °C, respectively. Characterizations of these catalysts with multiple techniques show that the enhanced catalytic activities are strongly related to the zeolite Si/Al ratios of the catalysts, where an increase of zeolite Si/Al ratio is favorable for the adsorption of propene, promoting the propene oxidation. This feature might offer a good opportunity to design and prepare highly efficient heterogeneous catalysts for removal of light olefins in the future.
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Polymers
·
2019
·Vol. 11
·期 5
·815
·
IF 3.164
Mihray Abdulla,Ahmat Ali,Ruxangul Jamal,Tursunnisahan Bakri,Wei Wu,Tursun Abdiryim
Heavy metal ions in water, cosmetics, and arable land have become a world-wide issue as they cause a variety of diseases and even death to humans and animals when a certain level is exceeded. Therefore, it is necessary to development a new kind of sensor material for the determination of heavy metal ions. In this paper, we present an electrochemical sensor based on composite material (thiol(–SH) grafted poly(3,4-proplenedioxythiophene) (PProDOT(MeSH)2)/ porous silicon spheres (Si) composite, denoted as PProDOT(MeSH)2@Si) from the incorporation of thiol(–SH) grafted poly(3,4-proplenedioxythiophene) (PProDOT(MeSH)2) with porous silicon spheres (Si) for the electrochemical detection of heavy metal ions (Cd(II), Pb(II), and Hg(II)). The PProDOT(MeSH)2@Si composite was synthesized via a chemical oxidative polymerization method. The structure and morphology of PProDOT(MeSH)2@Si composite were characterized by Fourier transform infrared (FT-IR), Ultraviolet–visible spectroscopy (UV–Vis), X-ray diffraction (XRD), scanning electron microscope (SEM), Transmission electron microscope (TEM), and Brunauer−Emmett−Teller (BET). Furthermore, the electrochemical performance of PProDOT(MeSH)2@Si was evaluated by detecting of Cd(II), Pb(II), and Hg(II) ions using the differential pulse voltammetry (DPV) method. The relationship between structural properties and the electrochemical performance was systematically studied. The results showed that the entry of two thiol-based chains to the monomer unit resulted in an increase in electrochemical sensitivity in PProDOT(MeSH)2,which was related to the interaction between thiol group(-SH) and heavy metal ions. And, the combination of PProDOT(MeSH)2with Si could improve the electrocatalytic efficiency of the electrode material. The PProDOT(MeSH)2@Si/GCE exhibited high selectivity and sensitivity in the rage of 0.04 to 2.8, 0.024 to 2.8, and 0.16 to 3.2 μM with the detection limit of 0.00575, 0.0027, and 0.0017 µM toward Cd(II), Pb(II), and Hg(II), respectively. The interference studies demonstrated that the PProDOT(MeSH)2@Si/GCE possessed a low mutual interference and high selectivity for simultaneous detection of Cd(II), Pb(II), and Hg(II) ions.Keywords:thiol(–SH), poly(3,4-proplenedioxythiophene), porous silicon spheres;electrochemical sensor;heavy metal ions;simultaneous detection
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CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Qi Song,Zhao-Hui Zhang,Zheng-Yang Hu,Shi-Pan Yin,Hao Wang,Zhen-Wu Ma
B 4 C ceramics were fabricated by spark plasma sintering with 5% (Ti 3 SiC 2 +Si) as sintering aid. The effects of sintering temperatures and sintering aid on microstructures and properties of B 4 C ceramics were investigated. The results indicated that the addition of a small amount of (Ti 3 SiC 2 +Si) could effectively improve the sintering characteristic of B 4 C ceramics and reduce the sintering temperature. The as-sintered ceramics fabricated at 1700 °C exhibited excellent mechanical properties , including a super-high Vickers hardness of 38.4 GPa, a high flexural strength of 457.6 MPa and a good fracture toughness of 5.61 MPa m 0.5 . Following reasons may be responsible for the improvement of the hardness of B 4 C ceramics: high relative density due to the combination use of (Ti 3 SiC 2 +Si) sintering aids and SPS technology, fine-grained structure of the B 4 C ceramics benefited from the low sintering temperature, formation of the second phases TiB 2 and SiC by chemical reaction and existence of the nano-sized unit of (TiB 2 +SiC) in B 4 C grains.
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JOURNAL OF MEMBRANE SCIENCE
·
2019
·
IF 7.015
Haicheng Jiang,Qi Zhao,Panpan Wang,Jun Ma,Xuedong Zhai
Fabricating high-flux, low-fouling gravity-driven membranes (GDM) has proved to be an extremely challenging work. In this study, a novel tailored amphiphilic multi-arms polymer poly(propylene glycol)-silane-poly(ethylene glycol) (PPG-Si-PEG) was synthesized and blended into Polyvinylidene Fluoride (PVDF) matrix to fabricate GDM via nonsolvent induced phase separation method. The incorporation of multi-arms polymers affected phase separation and surface segregation behaviors, resulting in the formation of more porous structure, which were demonstrated by scanning electron microscopy (SEM). Moreover, the hydrophilic PEG arms in polymers were enriched onto membrane surface through surface segregation and utilized to improve the hydrophilicity of membranes, which were confirmed by Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and contact angle measurement. The separation and antifouling properties of the membranes were evaluated by using gravity as the driving force, employing bovine serum albumin (BSA) as the model foulant. The water flux of membranes increased from 4.6 L m −2 h −1 for the control membrane to 12.1 L m −2 h −1 for PVDF/PPG-Si-PEG∼5% membrane. The antifouling properties of modified membranes were effectively improved in comparison with that of control membrane. The flux recovery ratio, especially for PVDF/PPG-Si-PEG∼5% membrane, was up to 99.4%. This study provided a new method for antifouling modification of GDM.
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MATERIALS & DESIGN
·
2018
·
IF 4.525
Haibo Ouyang,Guibiao Li,Cuiyan Li,Jianfeng Huang,Jie Fei,Jing Lu
C/C-Zr-Si-O composites were prepared by carbothermal reduction of hydrothermal co-deposited ZrO 2 , SiO 2 , and C. The bulk density of composites reached 1.71 g/cm 3 with 8 cycles of co-deposition. The matrix of the composites includes ZrC, SiC, ZrO 2 , and SiO 2 with fine grain size (300–500 nm) and homogeneous distribution. The mass and linear ablation rate of C/C-Zr-Si-O composites were 0.112 mg/cm 2 ·s and 0.46 μm/s, respectively, under a plasma flame for 120 s. The attractive ablation resistance of the composites resulted from its unique structure, which tends to form a continuous ZrO 2 -SiO 2 glass layer in the ablation center, a layer of SiO 2 -ZrO 2 bubbles in the transition region, and fluffy SiO 2 nanowires layer in the heat-affected region. These ablation layers were barriers to restrain the diffusion of oxidative gas and heat. The C/C-Zr-Si-O composites provide an alternative ceramics system with attractive ablation resistance, while carbothermal reduction of hydrothermal co-deposited oxides is a feasible method for the structural design of carbon fiber reinforced ultra-high temperature ceramic.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2018
·
IF 3.779
Jiarong He,Lingzhi Zhang
Polyvinyl alcohol grafted poly (acrylic acid) (PVA- g -PAA) is synthesized through graft polymerization of acrylic acid (AA) onto PVA backbone via a free radical reaction. PVA- g -PAA is used as a water-soluble binder for silicon (Si) anodes in lithium-ion batteries (LIBs). The enhanced adhesion strength , excellent flexibility and high electrolyte uptake after grafting reaction render PVA- g -PAA a robust binder for Si anodes. Compared to linear PVA, PAA and CMC , optimal Si-PVA- g -10PAA electrode exhibits better cycle stability, higher Coulombic efficiency and more excellent rate capability, possessing a high electrical conductivity , low SEI/charge transfer resistance and fast lithium-ion diffusion coefficient . PVA- g -PAA binder not only maintains the electrode's mechanical and electrical integrity, facilitates a favorable electrochemical kinetics, but also assists in forming a stable SEI layer on Si surface upon long-term cycling. Such a strategy sheds light on the design of novel polymer binders for practical applications of high-capacity active materials with great volume change.
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