JOURNAL OF ALLOYS AND COMPOUNDS
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2021
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IF 5.316
Amir Mahmoud Makin Adam,Madeha Ishag Adam,Chunmiao Zhang,Baffa Haruna,Mingzhu Chi,Xiong Li,Jia Kang Wan,Mujtaba Aminu,Girum Girma Bizuneh,Min Deng,Aimei Zhu,Qiugen Zhang,Qinglin Liu
Developing highly active Pd-based nanocatalysts with a well-organized structure is desired for direct alcohol fuel cell commercialization. In this study, room temperature seed mediated growth strategy has been successfully developed to prepare ternary Pd@Cd x -Ag y core-shell as advanced novel non-Pt anode nanocatalysts for ethanol oxidation reaction EOR in alkaline electrolyte . The introduction of oxophilic Cd and Ag metals into Pd nanocatalysts can reduce the adsorption energy of OH ads on the Pd@Cd x -Ag y nanocatalysts and inhibit the CO ads on the Pd surface. Morphological characterization demonstrates that the as-synthesized Pd@Cd x -Ag y nanocatalysts are well-organized core-shell nanostructure with Pd NPs as the core and Cd-Ag alloy as the shell. Moreover, electrochemical results indicate that the Pd@Cd 1 -Ag 1 core-shell catalyst exhibit a remarkable electrochemical activity ( 2995.76 mA mg Pd − 1 ), excellent CO tolerance and long-term durability compared to those of Pd@Cd ( 1285.9 mA mg Pd − 1 ), Pd@Ag ( 2423.52 mA mg Pd − 1 ) and commercial Pd/C (JM) ( 477.4 mA mg Pd − 1 ) nanocatalysts. The excellent catalytic activity and stability of Pd@Cd 1 -Ag 1 nanocatalyst can be associated to their huge electrochemical active surface area, positive influence of Cd-Ag NPs on Pd NPs and the unique well-organized core-shell nanostructure. These results suggested that the as-synthesized Pd@ C d x -Ag y core-shell could serve as advanced catalysts towards alkaline DEFCs.
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Surfaces and Interfaces
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2021
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IF 4.837
Xueyan Bian,Jiangtao Xu,Jing Yang,Ka-lam Chiu,Shouxiang Jiang
In this study, silver (Ag) is deposited onto polyester fabric through a magnetron sputtering system. The argon flow rate and sputtering time are both controlled to produce Ag nanoparticles of different sizes on the polyester substrate with different gap distances. The scanning electron microscope images, X-ray diffraction spectra, and Raman intensity are used to evaluate the produced substrates. With an average grain size of ~ 46 nm, Ag particles deposited at an argon flow rate of 200 sccm on polyester fabric (AP-200) provides the best SERS performance of 33,625.34 counts towards a 10 −3 M MB solution. The results show that the AP-200 SERS substrate is highly sensitive, reproducible and stable, and it also demonstrates good reusability. Image of “hotspots” that forms between two Ag nanoparticles based on electric field distribution is simulated by the finite-difference time-domain (FDTD) method which is used to explain the phenomenon of signal enhancement. In addition, AP-200 is used to directly collect R6G from an irregular surface, and shows high sensitivity with a limit of detection of 1 ppm.
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INDUSTRIAL CROPS AND PRODUCTS
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2021
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IF 5.645
Zongyuan Zhu,Yanbing Liu,Wenjie Cong,Xubo Zhao,Jidon Janaun,Tao Wei,Zhen Fang
A heterogeneous CaO/Ag nano catalyst was developed and applied for biodiesel production from transesterification of soybean oil. The silver performed synergistic effects with CaO on promoting biodiesel production. The CaO/Ag nano catalysts exhibited abundant strong basic sites with larger BET surface area (7.02 vs 2.05 m 2 /g), pore diameter (58.84 vs 37.08 nm) and pore volume (0.070 vs 0.016 cm 3 /g), which significantly reduced mass transfer resistance of triglycerides during transesterification and improved the mass transfer constants. Response surface methodology was applied to investigate the influence reaction parameters and optimize biodiesel yield. A maximized biodiesel yield of 90.95 ± 2.56 % was achieved using methanol:oil molar ratio of 13, CaO/Ag loading of 5%, reaction time of 90 min and reaction temperature of 72℃. The optimized biodiesel yield for CaO catalyzed transesterification was 88.40 ± 3.34 %, using similar reaction conditions but with 180 min of reaction time. Both nano catalysts were consecutively reused for five times. Kinetic and thermodynamic studies of CaO and CaO/Ag catalyzed transesterification were performed and compared. Economic evaluation of biodiesel production using CaO and CaO/Ag was performed and compared to provide insights for heterogeneous catalyst application for biodiesel production on industrial scale.
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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
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2021
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IF 4.098
Xiaoran Tian,Peng Zhai,Jiaqi Guo,Qian Yu,Lingzi Xu,Xinghua Yu,Rui Wang,Xianming Kong
Plasmonic cotton gauze-Ag composite were fabricated through a simple, instant and cost-effective way, in which the Ag NPs were immobilized on the surface of cotton gauze through in-situ growth process. The in-situ growth of Ag NPs was started from electroless-immobilized Ag seeds on the surface of cotton fiber, which could form numerous hot spots for SERS compared with current method. The cotton gauze-Ag composite was employed as versatile substrate in surface-enhanced Raman scattering (SERS) spectroscopy. The plasmonic cotton gauze-Ag exhibited excellent uniformity, temporal stability and enhanced effect for SERS measurement. The detection limit of P-aminothiopheno (PATP) was 10 -8 M. Furthermore, the plasmonic cotton gauze-Ag composite presented excellent flexibility and adsorption capability, which enable to adsorb and detect pesticide residue from irregular surface of cucumber directly by simple swabbing process, the detection limit could achieve 0.1 ppm. The cotton gauze-Ag composite also shown excellent selectivity is SERS sensing. The fabrication method could be simply extended to other cellulose compound, such as absorbent cotton, paper and even for natural fibers. This study proposed a new method for fabricating the cost-effective, eco-friendly and flexible SERS substrates.
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高影响因子
MICROCHEMICAL JOURNAL
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2021
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IF 4.821
Ling Yao,Lei Ouyang,Jiping Lv,Pei Dai,Lihua Zhu
There is an increasing demand for rapid and sensitive detection of hydrophobic contaminants in foods. A rapid and sensitive surface enhanced Raman scattering (SERS) detection method was developed for this purpose, based on the surface modification of nano-Ag aggregates, which had rich hot spots and controllable hydrophobicity. Cationic surfactants with different carbon chain lengths were employed to modify the aggregation of Ag nanoparticles. The adsorption of cationic surfactants on nano-Ag aggregates increased the hydrophobicity of the surface of the nano-Ag aggregates as the SERS substrate. By changing the carbon chain length of the surfactant, the hydrophobicity of the SERS substrate was able to be tuned to match with the hydrophobicity of the contaminants to be detected. Different hydrophobic contaminants such as Auramine O, Sudan I and Sudan III could be quantitatively detected, with a detection limit as low as 6.1 × 10 −8 , 7.5 × 10 −9 , 2.1 × 10 −9 mol L −1 , respectively. Compared with the traditional inorganic salt aggregation method which was unable to meet the requirements of direct quantitative detection in the sample matrices, the developed method was confirmed to have the advantages of low detection limit, good reproducibility (relative standard deviation (RSD) is less 7.6%), short operation time (about 1 min), and no need of any complicate pretreatment for sample preparation.
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CHEMICAL PHYSICS LETTERS
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2021
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IF 2.328
Qianqian Shang,Xin Tan,Mingcan Chen,Songyue Han,Tao Yu
High-efficient SERS substrates containing dense hot spots were fabricated by assembling 3D Ag nanoflowers (AgNFs)@Au-FTO substrate by using citrate ions as the shape-guiding agent. The vertical growth of 3D AgNFs could be attributed to the synergistic effects of the concentration gradient layer of Ag + and the density gradient of the charge carrier. Combined with the simulation result of FDTD method, the enhanced SERS sensitivity and repeatability of AgNFs@Au-FTO could be attributed to the enlarged specific surface area, and the improved density of hot spots contributed by the overlap between the vertically stacked AgNSs with a high population of sharp edges.
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CARBOHYDRATE POLYMERS
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2021
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IF 9.381
Sufeng Zhang,Chen Hua,Bin He,Pengbing Chang,Min Du,Ye Liu
Flexible electronics products have attracted wide attention because of their excellent flexibility, conductivity and stability. In this study, the liquid phase reduction method was used to in situ reduce fractal-structured silver particles (FSSPs) on cellulose surface to prepare conductive paper with excellent conductivity, and good stability and flexibility. The experimental results show that when the mass ratio of silver to cellulose was 1.5:1, the sheet resistance of conductive paper is as low as 0.02 Ω·sq −1 , and the conductivity reaches 1041.33 S cm −1 , which shows excellent conductivity. In order to expand the application of conductive paper in the field of flexible wearable electronic products, the mechanical stability and oxidation resistance of conductive paper were tested. The results show that the conductive paper has good stability and is expected to replace the flexible electronics products made of plastic.
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CHEMICAL ENGINEERING JOURNAL
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2021
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IF 13.273
Guodong Zhang,Runcheng Zhang,Fei Wang
Although activated carbon (AC) can significantly enhance hydrate nucleation kinetics due to abundant specific surface area and pore texture, the promotion drastically degenerates under low driving force and large water contents. Taking exceptional heat transfer of silver into account, silver nanoparticles were immobilized on activated carbon by in situ reduction method, giving rise to silver nanoparticle coated activated carbon (Ag-NP@AC), and the performance of Ag-NP@AC on hydrate formation kinetics was evaluated. Hydrate nucleation loaded by activated carbon was governed by external nucleation and that in inner pores, so slow hydrate nucleation was observed under low driving force and large water contents, where inner nucleation is hindered, and 500.67 min is required to induce hydrate nucleation at low overpressure (Δ P = 2.1 MPa), while 1145.4 min is inevitable for large water content ( R w = 1.4). Encouragingly, the presence of Ag nanoparticles significantly improves this limitation by enhancing external nucleation, Ag-NP@AC shortens hydrate induction time to a large extent, which reduces by 96.88% and 85.25% under mild condition (Δ P = 2.1 MPa) and large water content ( R w = 1.4), respectively. These findings provide new perspective on the application of porous carbon materials on hydrate-based solidified natural gas technologies.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2021
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IF 8.128
Yang Li,Zhi Liu,Zhao Li,Qiu Wang
Constructing noble metal-doped g-C 3 N 4 /carbon composites is a feasible route to overcome the intrinsic drawbacks of pristine g-C 3 N 4 for enhanced activity of CO 2 photoreduction. Herein, a novel Ag-doped g-C 3 N 4 /biomass-derived carbon composite with hollow bird's nest-like (Ag-g-C 3 N 4 /BN-C) is designed and prepared via a simple yet effective one-step pyrolysis method. In the Ag-g-C 3 N 4 /BN-C, the highly-dispersed Ag nanoparticles (20–30 nm) with the surface plasmon resonance (SPR) effect act as a significant cocatalyst not only to efficiently trap the photogenerated electrons from g-C 3 N 4 to boost the separation of photogenerated electron-hole pairs but also to produce additional active “hot electrons”, while the conductive quasi-spherical hollow structure of BN-C doubles the specific surface area with multiple reflections of light, providing abundant active sites and more utilization efficiency of light energy. As a result, the Ag-g-C 3 N 4 /BN-C exhibits a remarkably enhanced CO evolution rate of 33.3 μmol·g −1 ·h −1 without addition of any sacrificial reagents and photosensitizers, superior to those of both the pristine g-C 3 N 4 and many reported g-C 3 N 4 -based counterparts. The findings of this work demonstrate a good indication for integrating g-C 3 N 4 with SPR-dependence noble metal and renewable biomass-derived carbon for enhanced CO 2 photoreduction, which may be extended to modify other semiconductor materials for more photocatalytic applications with enhanced activity.
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ACS Applied Materials & Interfaces
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2021
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IF 9.229
Yu Chen,Senqing Fan,Boya Qiu,Jiaojiao Chen,Zenghui Mai,Yilin Wang,Ke Bai,Zeyi Xiao
A bimetallic catalytic membrane microreactor (CMMR) with bimetallic nanoparticles in membrane pores has been fabricated via flowing synthesis. The bimetallic nanoparticle is successfully immobilized in membrane pores along its thickness direction. Enhanced synergistic catalysis can be expected in this CMMR. As a concept-of-proof, Cu–Ag core–shell nanoparticles have been fabricated and immobilized in membrane pores for p-nitrophenol (p-NP) hydrogenation. Transmission electron microscopy (TEM) for the characterization of the bimetallic core–shell nanostructure and X-ray photoelectron spectroscopy (XPS) for the characterization of the electron transfer behavior between Cu–Ag bimetal have been performed. The Ag shell on the core of Cu can improve the utilization of Ag atoms, and electron transfer between bimetallic components can promote the formation of high electron density active sites as well as active hydrogen with strong reducing properties on the Ag surface. The dispersed membrane pore can prevent nanoparticle aggregation, and the contact between the reaction fluid and catalyst is enhanced. The enhanced mass transfer can be achieved by the plug-flow mode during the process of hydrogenation catalysis. The p-NP conversion rate being over 95% can be obtained under the condition of a membrane flux of 1.59 mL·cm–2·min–1. This Cu–Ag/PES CMMR has good stability and has a potential application in industry.
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MATERIALS & DESIGN
·
2020
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IF 6.289
Lizhu Guan,Ling Weng,Qiong Li,Xiaorui Zhang,Zijian Wu,Yingyi Ma
With a strong ability in tailoring molecular structure, nanoscale morphology, and nanodomains, the ferromagnetic metal-organic framework (MOF, M = transition metal) has been considered an advantageous candidate material for dielectric nanocomposites. Herein, a pristine content-controlled Ag nanoparticle driving Ni metal-organic framework (Ag-NiMOF) ultra-thin 2D ferroelectric nanoplatelets have been synthesized by a two-step method, and applied to the PVDF-based energy storage materials. Comprehensive tests and multi-physics simulations have been conducted on the electrical properties of materials. The electric displacement-electric field (D-E) hysteresis loops of the composites show that the discharge density of 6.987 J/cm 3 ~ 2300 kV/cm has been achieved with a 10 wt% filler addition, namely 10Ag-NiMOF/PVDF, which indicates a 5.36 times increase in the discharge density. Finite element simulation further verifies the improvement of the displacement and electrical breakdown strength of the composites. This high performance indicates that both of the centrosymmetric lattice nanodomains of NiMOF and the electrons introduced by Ag nanoparticle would help induce greater polarization in the nanocomposite. Furthermore, the Coulomb blockade effect exerted by the Ag nanoparticle with an appropriate particle size and a fractional concentration can significantly improve the electrical breakdown strength. This 2D hybrid particle provides a novel idea for modifying dielectric composites for high storage device applications.
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Catalysts
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2020
·Vol. 10
·期 10
·1102
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IF 3.52
Fengyang Ju,Jinjin Zhang,Weiwei Lu
The electrochemical reduction of CO2is a promising way to recycle it to produce value-added chemicals and fuels. However, the requirement of high overpotential and the low solubility of CO2in water severely limit their efficient conversion. To overcome these problems, in this work, a new type of electrolyte solution constituted by ionic liquids and propylene carbonate was used as the cathodic solution, to study the conversion of CO2on an Ag electrode. The linear sweep voltammetry (LSV), Tafel characterization and electrochemical impedance spectroscopy (EIS) were used to study the catalytic effect and the mechanism of ionic liquids in electrochemical reduction of CO2. The LSV and Tafel characterization indicated that the chain length of 1-alkyl-3-methyl imidazolium cation had strong influences on the catalytic performance for CO2conversion. The EIS analysis showed that the imidazolium cation that absorbed on the Ag electrode surface could stabilize the anion radical (CO2•−), leading to the enhanced efficiency of CO2conversion. At last, the catalytic performance was also evaluated, and the results showed that Faradaic efficiency for CO as high as 98.5% and current density of 8.2 mA/cm2could be achieved at −1.9 V (vs. Fc/Fc+).Keywords:electrochemical reduction of CO2;ionic liquids;propylene carbonate;imidazolium cation
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