Nanoparticle Composite Materials Research Articles

Enhanced thermal management by introducing nanoparticle composite phase change materials for cooling multiple heat sources systems

In this paper, paraffin mixed with nanoparticles Al2O3, CuO, and multi-walled carbon nanotubes (MWCNTs) were prepared for cooling multiple heat sources. For thermal management of heat sources, performances of the composite phase change materials (PCMs) were investigated at different heating power. Enhanced performance in terms of heat sources temperature, temperature difference between two heat sources, and thermal resistance was experimentally tested and analyzed at various mass fractions of nanoparticle and various power levels. It is found that by using 1.0 wt% Al2O3 composite PCMs the minimal thermal resistance is achieved at the range from 0.63 °C/W to 0.71 °C/W for all power levels, and the heat storage and heat conduction of the presented composite PCMs are enhanced as well as the melting ratio. At 8 W power level, the temperature of the heat source 1 for 1.0 wt% Al2O3 composite PCMs decreases by 17.4% compared to that for pure paraffin.

Biomass-derived paper-based nanolignin/palladium nanoparticle composite film for catalytic reduction of hexavalent chromium

In this study, paper-based catalytic composite films were prepared by synthesizing nanolignin on a filter paper (FP) and in situ reducing Pd ions to Pd nanoparticles (NPs). Alkaline lignin (AL) NPs were controllably prepared using industrial AL via two routes: “loading and then regeneration” and “regeneration and then loading.” The NPs prepared using the former method were labelled as LAL NPs, and those prepared using the latter were labelled as RAL NPs. The as-prepared NPs were loaded into the fiber framework of the FP to obtain paper-based AL NP composite material. The results showed that the AL NPs could be successfully prepared through both routes with similar dispersity and uniformity that were improved by the presence of FP. In addition, the size range of LAL NPs (26.6–92.7 nm) was broader than that of RAL NPs (37.3–85.0 nm). The AL NPs on FP were then employed as a reducing agent for the reduction of Pd2+. The concentration of the AL solution (0.43 %–3.07 %) influenced the content of AL NPs on the FP, and a higher AL NP content resulted in higher Pd NP content. Furthermore, the obtained paper-based nanolignin/palladium nanoparticles (AL-Pd NPs/FP) composite films were used for the catalytic reduction of Cr6+. They efficiently reduced the highly toxic Cr6+ to the less toxic Cr3+, and among them, the RAL-Pd NPs/FP film with a Pd NP content of 0.18 mg/mL required only 5 min to completely catalyze the reduction of Cr6+.

Investigation into the Structural, Chemical and High Mechanical Reforms in B4C with Graphene Composite Material Substitution for Potential Shielding Frame Applications.

In this work, boron carbide and graphene nanoparticle composite material (B4C–G) was investigated using an experimental approach. The composite material prepared with the two-step stir casting method showed significant hardness and high melting point attributes. Scanning electron microscopy (SEM), along with energy dispersive X-ray spectroscopy (EDS) analysis, indicated 83.65%, 17.32%, and 97.00% of boron carbide + 0% graphene nanoparticles chemical compositions for the C-atom, Al-atom, and B4C in the compound studied, respectively. The physical properties of all samples’ B4C–G like density and melting point were 2.4 g/cm3 density and 2450 °C, respectively, while the grain size of B4C–G was in the range of 0.8 ± 0.2 µm. XRD, FTIR, and Raman spectroscopic analysis was also performed to investigate the chemical compositions of the B4C–G composite. The molding press composite machine was a fabrication procedure that resulted in the formation of outstanding materials by utilizing the sintering process, including heating and pressing the materials. For mechanical properties, high fracture toughness and tensile strength of B4C–G composites were analyzed according to ASTM standard designs. The detailed analysis has shown that with 6% graphene content in B4C, the composite material portrays a high strength of 134 MPa and outstanding hardness properties. Based on these findings, it is suggested that the composite materials studied exhibit novel features suitable for use in the application of shielding frames.

One-step synthesis of MOF-derived Cu@N-doped carbon composites as counter electrode catalysts for quantum dot-sensitized solar cells

The nitrogen-doped carbon supported Cu nanoparticles composite materials (Cu@N-C) have been recognized as the excellent counter electrode catalysts for quantum dot-sensitized solar cells (QDSCs). Herein, the Cu@N-C composites were synthesized via facile one-step pyrolysis of nitrogen-containing Cu-MOFs precursor. By controlling the reaction temperature from 600 to 1000 °C, the Cu@N-C-x (x is the pyrolysis temperature) catalysts are obtained. An ordered nitrogen-doped graphitized carbon lattice around Cu nanoparticles of the Cu@N-C-x improves the conductivity of counter electrodes (CEs), and uniform doping of nitrogen in the carbon enhances the wettability of the carbon material. The Cu@N-C-900/FTO CEs prepared exhibit higher electrocatalytic activity than both pristine N-C/FTO and Cu@C/FTO CEs, which could be ascribed to the synergistic effect between abundant CuxS catalytic active sites and nitrogen-doped graphitic carbon. It is noted that the Cu@N-C-900/FTO CEs also show superior catalytic activity compared to CuS@g-CNx/FTO CEs due to the higher specific surface area and porosity of the carbon skeleton. As a result, the QDSCs based on Cu@N-C-900/FTO CEs achieved the highest PCE of 8.63%, which is slightly higher than that of Cu@C/FTO CEs (8.20%) and CuS@g-CNx CEs (8.37%), and significantly higher than that of N-C/FTO CEs (6.52%).

Microbiological synthesis of denitrifying bacteria-iron nanopartical composite material and its eminent performance in removal of nitrate-N

Denitrifying bacteria-Iron nanoparticles (FeNPs) composite material was biosynthesized to get rid of Nitrate-N. FeNPs were synthesized by the biological reducing capacity of denitrifying bacteria without additional chemical reagent. And then they were loaded in the denitrifying bacteria to fabricate composite material which were characterized by UV–Vis spectra, XPS, FTIR and TEM confirming the FeNPs are embedded in the bacteria and fully protected by the bacteria. The composite material can remove nearly 100% nitrate–N in 420 min without more ammonia-N generation. FeNPs loaded in the Denitrifying bacteria-FeNPs composite material can act as the electron donor for denitrifying bacteria to complete the biological denitrification process which will accelerate denitrification rate without releasing additional Ammonia-N. The denitrifying bacteria can protect FeNPs from being oxidized in the environment and from reacting with nitrate-N to produce ammonia-N. FeNPs recovering process and denitrification process are in progress at the same time since denitrifying bacterium can synthesize FeNPs by recovering Fe2+ and Fe3+ in the system at all times.

Formation of an Ag/MoS2 composite structure through photothermal conversion

Precious metal nanoparticle composite two-dimensional materials have attracted widespread attention due to their excellent photothermal properties. A new method for selective modification of silver nanoparticles on atomic layered molybdenum disulfide (MoS2) is presented. An Ag/MoS2 composite structure is formed under the continuous irradiation of an 808 nm laser. The heat generated by the photothermal conversion of the MoS2 nanosheets plays a major role in the growth of silver nanoparticles. The Ag/MoS2 composite structure is analyzed via the combination of the absorption spectrum, scanning electron microscopy, particle size distribution, and Raman spectroscopy. The photothermal conversion can drive nanometer composite heterogeneous material growth.

Preparation of Silver Nanoparticle Composite Material and Its Role in Electrocardiogram Treatment of Acute Myocardial Infarction

The surface resonance scattering of silver nanoparticles, commonly used to enhance the matrix of the Raman, is the most active of all metal nano particles which can greatly improve the sensitivity of the detected molecules. At the same time, the sterilization ability of silver is also highly recommended in the field of biology. In this study, cytosine nucleoside was used as a template to quickly synthesize silver-based composite nanomaterials (Ag–C/Au) with enhanced fluorescence and good water solubility. Then, the fluorescence spectrum, lifetime, the ultraviolet-visible absorption spectrum of the material, and the size and shape of the grain size were studied through characterization. After that, the interaction between the silver-based composite nanomaterial Ag–C/Au and the recombinant protein ephrin-b2 was studied by spectroscopy, and the mixed metalloprotein was used for electrocardiogram treatment of myocardial infarction in SD rats to establish a rat modeling, then the rats were grouped according to the different injections, and the heart rhythm variability (HRV) of different groups of rats with myocardial infarction (MI) was recorded. Finally, the program electrical stimulation (PES) was used to analyze the ventricular effective refractory period (VERP) and ventricular arrhythmia (VAs) in rats. In the experiment, Ag–C/Au nanomaterials produced strong yellow fluorescence under 370 nm ultraviolet excitation, with an approximate particle size of 1.6 nm; through spectral data fitting, it was found that the recombinant protein ephrin-b2 could be adsorbed on the surface of the composite nanomaterials, making the intensity of the characteristic peak decreased; the myocardial indicators of myocardial infarction rats based on ephrin- b2 + Ag–C/Au group were significantly improved, while the grouping of rats using Ag–C/Au alone didn't affect the electrophysiological characteristics after myocardial infarction, that is, ephrin-b2 could improve arrhythmia after myocardial infarction, and the improvement effect would be further strengthened when Ag–C/Au was added.

Fe3O4/Graphene Aerogel as High-Performance Flexible Anode for Sodium-Ion Battery

To overcome the volume expansion and poor electrical conductivity of metal oxides, graphene aerogel encapsulated Fe3O4 nanoparticles composite material was synthesized by hydrothermal self-assembled method. Fe3O4 was synthesized in situ during the self-assembled process, effectively relieving volume expansion and pulverization of metal oxides by the encapsulation of graphene aerogels (termed Fe3O4@rGA). Besides, the graphene aerogel enhances the conductivity of the composite material. The Fe3O4@rGA used as anode material for sodium ion batteries in this study displayed an excellent initial capacity of 220 mA h g−1 at 100 mA g−1, and even showed reversible capacity of 82 mA h g−1 at 10 A g−1.

Formation of one-dimensional arrays of nanoparticles using segmented polyurethane nanofibers prepared by electrospinning

The number density and the arrangement of metal nanoparticles in composite materials have a significant effect on their performance and hence their suitability for use in sensors and devices. Forming one-dimensional arrays of metal nanoparticles is one way of controlling their number density and arrangement in the devices. In this study, we fabricated one-dimensional arrays of gold nanoparticles by adsorbing them on linearly distributed hard segments present on the surfaces of segmented polyurethane nanofibers, which were produced by electrospinning under a stretching force. The length of the one-dimensional array was approximately 500 nm. Furthermore, the interparticle distance was almost constant at approximately 14 nm. Thus, the proposed method is suitable for fabricating one-dimensional arrays of metal nanoparticles with high precision.

Seed-mediated growth of Au core–Pd shell-structured nanoparticles on a polymer nanofibrous mat as a highly active photocatalytic composite material

Photocatalytic technologies have received extensive attention as green catalysts. Here, we successfully designed gold (Au) core–Palladium (Pd) shell-structured nanoparticles (NPs) as a nanoreactor, in which the Pd shell provides the active sites and Au core offers strong plasmonic properties. We then used the seed-mediated growth approach to fabricate the Au core–Pd shell-structured nanoparticles on a polyvinyl alcohol (PVA) nanofibrous mat as a highly active photocatalytic composite material for hydrogenation reactions under room temperature. Our results show that the Au core–Pd shell-structured nanoparticles are more effective in catalyzing the hydrogenation of styrene than the Pd nanoparticles. The photocatalytic experimental results show that the yields of ethylbenzene under light conditions are higher than that under 60 °C in the dark. This shows that the PVA/Au NP/Pd NP composite material can efficiently utilize heat from light to promote catalytic reactions via photothermal effects. The PVA/Au NP/Pd NP composite material not only exhibits a very high photocatalytic efficiency, but can also easily recover from the reaction. The work offers a simple and efficient strategy for recyclable and highly active catalysts for light-driven organic reactions.

ANTI-MICROBIAL ACTIVITY OF SILVER NANO PARTICLES (AG-NPS) ON BACTERIA ISOLATED FROM DIABETIC FEET

Background: Silver nanoparticles (Ag NPS) have long been known to have powerful antimicrobial activities. The aim of this study: to synthesize of silver nanoparticles (Ag NPS) in chitosan composite for possible use in biological application. Objective: Chitosan – silver nanoparticles composite materials was synthesized by adding AgNo3 0.5 gm and NaOH solution to chitosan solution at 120 c. Different concentrations of chitosan 0.05 % - 0.125 % - 0.25 % - 0.5 % were used for synthesis. Chitosan – silver nanoparticle composite materials were characterized by Ultraviolet visible spectroscopy (UV), particles size and zeta potential (NCS) and transmission electron microscopy (TEM). Bacteria isolated from diabetic feet were used to test the bactericidal efficiency of synthesized chitosan – silver nanoparticles composite materials. Results: The bacteriological tests showed either bacterial growth inhibition or cell death occurred depending on the concentration of chitosan used. Antibacterial effect of chitosan – silver nanoparticles composite materials increased by increasing chitosan concentration. Conclusion: The presence of Ag- nanoparticles in different concentrations of chitosan composite was enough to significantly enhance antibacterial activity.

Photoswitchable Macroscopic Solid Surfaces Based On Azobenzene-Functionalized Polydopamine/Gold Nanoparticle Composite Materials: Formation, Isomerization and Ligand Exchange.

The facile preparation of dynamic interfaces is presented based on the combination of photoisomerizable azobenzenes and polydopamine (PDA)/Au nanoparticle composite materials. Azobenzenes with different spacer lengths (C3 , C6 ) and surface-binding groups (SH, NH2 ) were synthesized. The polymer layer on macroscopic quartz surface was prepared by the facile aerobic autopolymerisation of dopamine hydrochloride under basic conditions. The presence of redox-active catechol moieties meant that gold nanoparticles were formed on the polymer surface. The obtained UV-Vis spectroscopic results confirmed that following their successful assembly, the switching of azobenzenes on PDA/Au was not affected by the surface binding group and the spacer length of the azobenzene molecules under the measurement conditions. Furthermore, facilitated by the curved nature of the Au particles, the surface-bound azobenzene layer could be reconstructed by ligand-exchange processes, and the photochemical characterization of the mixed layer was performed.

Breakdown Field Strength Variations and Energy Density Limits of Nanoparticle Composite Materials

In response to the growing demand for renewable energy storage technologies, current research into nanoparticle (NP) composite materials seeks to push the boundaries of energy density for solid-state capacitive energy storage. To understand the limits of these composites, it is important to understand the electric field patterns and breakdown events that prevent such devices from storing more energy per unit volume. To this end, a novel breakdown path detection algorithm is designed to mimic breakdown events by using the internal electric fields to determine the breakdown voltage of simulated composite materials. This breakdown path detection model is used to calculate the energy density for over 1200 different geometries for BaTiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> NPs embedded in a P(VDFHFP) host matrix. These simulations reveal a large normalized variation in the volumetric energy density of up to 54%. Furthermore, these P(VDF-HFP)/BaTiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> composites are found to have only a modest improvement in energy density of 1.08× compared to the pure P(VDF-HFP) host; however, alternative hypothetical NP compositions composed of SrTiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> , SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , and HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> NP inclusions showed increases in energy density of up to 5.64× for SrTiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (volume fraction of 0.48), 8.87× for SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (volume fraction of 0.34), and 2.89× for HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (volume fraction of 0.38).

Bamboo-like nitrogen-doped porous carbon nanofibers encapsulated nickel-cobalt alloy nanoparticles composite material derived from the electrospun fiber of a bimetal-organic framework as efficient bifunctional oxygen electrocatalysts.

The development of low-cost bifunctional electrocatalysts with both a high activity and long durability is critical for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The reasonable design and construction of bifunctional electrocatalysts is the key to energy storage and energy conversion technologies. In this study, transition metal carbon nitrides were used as a substitute for the precious metal catalyst, the Ni-Co-BTC (metal organic framework (MOF)) mixed with polyacrylonitrile (PAN) using electrostatic spinning technology to prepare the bamboo-like nanofibers precursor (Ni-Co-BTC@PAN). A series of electrocatalytic materials (NiCo-X@N-CNFs-Ts, T = 700, 800, 900 °C) were synthesized with nitrogen-doped carbon nanofibers coated with NiCo alloy nanoparticles using high temperature carbonization at different temperatures. We studied the effects of different calcination temperatures and different Ni/Co molar ratios of NiCo-X@N-CNFs-Ts (T = 700, 800, 900 °C) on the bifunctional catalytic performance of the ORR/OER. The composite, NiCo-0.8@N-CNFs-800, exhibited a highly doped-N level, uniform NiCo alloy nanoparticle dispersion and decentralized NiCo-Nx active sites, therefore affording an excellent bifunctional electrocatalytic performance. The ORR onset potential on NiCo-0.8@N-CNFs-800 was 0.91 V and the half-wave potential (E1/2) was 0.82 V, the NiCo-0.8@N-CNFs-800 corresponded to the minimum potential of 1.61 V at the current density of 10 mA cm-2 among all of the NiCo-X@N-CNFs-Ts hybrids under the OER condition. The NiCo-0.8@N-CNFs-800 catalyst exhibited a low reversible overpotential of 0.79 V between the ORR (E1/2) and OER (Ej = 10 mA cm-2) with excellent stability, durability and methanol tolerance, even surprisingly superior to the commercial Pt/C and RuO2 catalysts. This work provides a general strategy and useful guidance for the design and development of a variety of multifunctional non-noble metal catalysts for energy applications.

A Facile Way to Synthesize Carbon-Coated LiMn0.7Fe0.3PO4/Reduced Graphene Oxide Sandwich-Structured Composite for Lithium Ion Batteries

Introduction Olivine-type LiMnPO4 which is a cathode material for lithium ion batteries exhibits a higher operating potential (4.1 V vs. Li+/Li) than LiFePO4 thus has gathered more attention in recent years. However, due to the low electron conductivity of LiMnPO4 and the Jahn-Teller effect of Mn3+, it is difficult to achieve satisfied cycle performance. Fe doping of 10-30 mol% is promising as a solution to this problem [1]. Graphene is a single atomic monolayer of graphite and has been found a variety of applications in energy conversion and storage devices, due to the excellent properties such as high carrier mobility (~10,000 cm2 V−1 s−1 at room temperature), structural flexibility, chemical and thermal stability, mechanical strength and ultrahigh theoretical specific surface area (2630 m2g−1) [2]. Previous studies have reported the improved performance of LiMPO4 (M = Fe, Mn and Co by combining with graphene. In particular, it is attractive that the active material is supported on both sides of graphene to form a sandwich structure. One is that active material particles can be highly loaded and interconnected by the highly conductive matrix formed by graphene. The other one is that the sandwich structure can be beneficial for suppressing the graphene restacking and active material particles agglomeration. It is reported that such a graphene-metal oxide nanoparticle composite material can greatly improve the performances of the anode. However, there is still lack of a facial way to obtain ideally sandwich-structured composite material for cathode [3]. We will introduce a facial and high efficient way to synthesize carbon-coated LiMn0.7Fe0.3PO4 (LMFP)/reduced graphene oxide (rGO) sandwich-structured composite for high power lithium ion batteries [4]. Results and discussion The synthesis of sheet-like carbon-coated LMFP/rGO composite material is shown in Fig. 1. First, 0.3 g of LMFP powder (without carbon coating, average particle size 200 nm), 3 mL of oxidized graphite suspension and 0.04 g of sucrose are dispersed in 100 mL of water. Thereafter, by ultrasonic treatment for 2.5 hours, the oxidized graphite gradually peels off to form graphene oxide, and at the same time, the LMFP nanoparticles are supported on the surface of the GO by interaction with the GO functional group. The dissolved sucrose is coated with GO and LMFP particles to form a polymeric coating. After lyophilization, carbon coated LMFP/rGO composite material (LMFP/rGO@C) having a sandwich structure was obtained by heat treatment at 700 degrees under a reducing atmosphere. LMFP/rGO@C, acetylene black and binder were mixed at a mass ratio of 8:1:1 and coated onto Al foil to obtain a cathode electrode. Electrochemical characteristics were evaluated by preparing a 2032 type coin cell using Li foil as the counter electrode. The electrolyte was 1 mol dm-3 LiPF6/EC-DEC (1: 2). SEM image of the synthesized LMFP/rGO@C composite material is shown in Fig. 2. It is clearly observed that all the LMFP particles are uniformly dispersed on the rGO surface at high density (50 to 100 particles mm-2), forming a sandwich structure. The total content of rGO and carbon coating is estimated to be about 7 wt% from TG. Figure 3 shows the discharge rate performance of LMFP/rGO@C and carbon coated only LMFP (LMFP@C). It was confirmed that the discharge capacity of LMFP/rGO@C is greatly improved compared with LMFP@C. This should be due to the formation of a good three-dimensional conductive network by graphene. Acknowledgement We thank Taiheiyo Cement Co., Ltd for the providing of LiMn0.7Fe0.3PO4 powders and NIMS for the TEM measurement. Reference 1) Gong, et.al., Energy Environ. Sci. 4, 3223 (2011). 2) S. Han, et.al., Small. 9 1173–1187 (2013). 3) Z.-S. Wu, et.al. Nano Energy. 1 (2012). 4) D. Ding, et.al., submitted. Figure 1

Silver nanoparticles decorated reduced graphene oxide (rGO) SERS sensor for multiple analytes

Selectivity and enhanced sensitivity for surface-enhanced Raman scattering (SERS) substrates are highly desirable attributes for their analytical applications. SERS substrate interaction with target molecules plays a key role in determining the enhancement magnitude and spectral profile of the SERS signal as well as their applications. Herein, we demonstrate a SERS active substrate based on reduced graphene oxide/silver nanoparticles (rGO/Ag NPs) composite material synthesized by a facile wet chemical route. The Ag NPs decorated rGO nanosheet has been achieved by reducing AgNO3 with ethylene glycol in the presence of poly vinyl pyrrolidone (PVP) and NaCl over layered graphene oxide. The addition of PVP stimulates the nano-phase growth as well as uniform distribution of the Ag NPs on rGO nanosheet. The well synthesized rGO/Ag composite was confirmed by using various characterization techniques such as FESEM, HRTEM, XRD, FTIR and Raman. Further, the rGO/Ag NPs composite material has been utilized as a platform for SERS based selective detection of Rhodamine-6G, 4-mercapto benzoic acid, and 2,4-dinitrotoluene analytes. The rGO/Ag NPs substrate demonstrates good homogeneity, stability and nanomolar sensitivity with Raman intensity enhancement of the order of 5 for Rh-6G and 4-MBA whereas 3 for 2,4-DNT. The observed enhancement of SERS signal for all the analytes has been attributes to the cumulative effect of rGO and Ag NPs.

Effects of Ni nanoparticles addition on the microstructure, electrical and mechanical properties of Sn-Ag-Cu alloy

The effects of Ni nanoparticles addition on the microstructure, electrical resistivity and mechanical properties such as elastic/shear moduli, microhardness and creep of Sn-3.0Ag-0.5Cu (SAC305; in wt.%) electronic interconnect materials have been investigated. Microstructure analysis of Sn-3.0Ag-0.5Cu-0.5 Ni nanoparticles (in wt.%) solder revealed that adding Ni nanoparticles has promoted the formation and growth of (Cu, Ni)-Sn intermetallic compound (IMC) in the bulk phase of the samples and the structure of composite material resulted refined. This finer structure and (Cu, Ni)-Sn IMCs in a composite solder resulted in improved mechanical and electrical properties with respect to the Sn-3Ag-0.5Cu reference alloy. Indeed, a comparison between the reference alloy and composite material doped with 0.5 wt.% Ni nanoparticles indicates that the improvement in elastic and shear modulus was 8% and 11.2%, respectively, whereas the microhardness value was increased about 16.7%. Moreover, in the electronic interconnect systems on organic solderability preservative (OSP)-Cu pad, a scallop-shaped Cu6Sn5 IMC was detected at their interfaces at early stage reaction. Increasing the reaction time, the growth of the Cu6Sn5 and the formation of a very thin Cu3Sn IMC layer was observed. However, in Sn-3.0Ag-0.5Cu-0.5 Ni nanoparticles composite material, a very stable (Cu, Ni)-Sn IMC grew at the interface between composite solder and (OSP)-Cu pad in absence of Cu3Sn IMC. In addition, a relatively fine Ag3Sn and (Cu, Ni)-Sn IMC appeared to be evenly dispersed in β-Sn matrix and the fine microstructure surely affect the overall properties of solder joints.

Highly Efficient and Non-Precious Metal for the Li-SOCl2 Battery Using Nitrogen Doped Carbon Supported Cu Nanoparticles

For lithium thionyl chloride batteries, the catalytic activity of the cathode material plays a crucial role in its electrochemical performance. In this paper, a poly (1-vinyl-3-methylimidazolium dicyanamide) ionic liquid (PIL) is selected as precursor to support CuO nanoparticles, and an efficient, non-precious metal nitrogen doped carbon supported Cu nanoparticles (N-C@Cu) composite material is designed and prepared for the lithium thionyl chloride battery cathode catalyst. X-ray diffraction (XRD) and high-resolution transmission electron microscope (HRTEM) verified that the supported CuO nanoparticles is reduced to Cu via carbon which formed from the thermally decompose of PIL. X-ray photoelectron spectroscopy (XPS) images confirm the existence of nitrogen doped carbon and Cu nanoparticles. Raman spectroscopy also demonstrate that the interaction between Cu and N-C provides more active sites. The N-C@Cu composite catalyst exhibits excellent activity in the reduction process of thionyl chloride, as can be seen from the materials display characteristics of lower discharge over-potential, and improved electron transfer of its rate-determining step. The rate performance, operating voltage and discharge capacity are all improved.

Synthesis and applications of epoxy-functionalized bi-functional magnetic molecularly imprinted polymers for polysaccharide adsorption

A polysaccharide-imprinted nanoparticle composite material with bi-functional monomers molecularly imprinted polymers (Bi-MMIPs) was successfully synthesized in aqueous solution by using starch as the template, 3-aminobenzeneboronic acid (APBA) as the functional monomer, 2-acrylamide-2-methylpropanesulfonic acid (AMPS) as the co-functional monomer, and ammonium persulfate (APS) as the initiator. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier-transform infrared (FT-IR) spectroscopy were used to characterized Bi-MMIPs. The adsorption and recognition characteristics of Bi-MMIPs for starch were investigated in detail by using the static method, dynamic method, and competitive adsorption experiments. The TEM, SEM and FT-IR results showed that the two functional monomers were loaded on the surface of Bi-MMIPs. Bi-MMIPs possessed very strong adsorption affinity and specific recognition for starch. The saturated adsorption capacity reached 13.88 mg/g, and the selectivity coefficients relative to glucosans Mr 5000 Da and 70000 Da were 2.67 and 3.77, respectively. Despite the imprinting factor of Bi-MMIPs (α=3.04), Bi-MMIPs were regenerated easily and exhibited excellent recognition, selectivity, and reusability for adsorbing starch. To elucidate the mechanism, APBA and AMPS showed synergy effect in synthesizing bi-functional monomers by providing reversible covalent bonds and hydrogen bonds, respectively, which could effectively enhance the spatial arrangement of combining sites for template molecular.

General Method for Determining Light Scattering and Absorption of Nanoparticle Composites

AbstractScattering and absorption from nanoparticles are of major importance in optical research as well as in a range of applications. The Kubelka–Munk two‐flux radiative transfer model gives a simple description of light scattering in nanoparticle composite materials, but inversion of experimental transmittance and reflectance data to obtain backscattering and absorption coefficients remains challenging. Here, a general method for evaluating these parameters from transmittance and reflectance spectra, combined with spectral angle resolved light scattering measurements is developed. The angular dependence is approximated by an extension of the empirical Reynolds–McCormick phase function, which is fitted to the experimental angle resolved light scattering data. This approach is verified by measurements on three typical nanoparticle/polymer composites containing plasmonic Au, ferromagnetic Fe3O4, and dielectric TiO2 particles. An approximation to the angular scattering pattern is further demonstrated, which can be applied to obtain the optical parameters using only reflectance and transmittance data, in cases where angle‐resolved measurements are not available. These results can be extended to a wide range of isotropic, anisotropic, and multiple scattering systems, and will be highly useful in the fields of light scattering coatings/metamaterials, UV‐shielding films, displays, absorption/scattering layers in solar cells and biological scatterers.