Surface Of Silicon Nanoparticles Research Articles

High-Branched Natural Polysaccharide Flaxseed Gum Binder for Silicon-Based Lithium-Ion Batteries with High Capacity.

Silicon-based anodes heavily depend on the binder to preserve the unbroken electrode structure. In the present work, natural flaxseed gum (FG) is used as a binder of silicon nanoparticles (SiNPs) anode for the first time. Owing to a large number of polar groups and a rich branched structure, this material not only anchors tightly to the surface of SiNPs through bonding interactions but also formed a hydrogen bonding network structure among molecules. As a result, the FG binder can endow the silicon electrode with stable interfacial adhesion and outstanding mechanical properties. In addition, FG with a high viscosity facilitates the homogeneous dispersion of the electrode components. When FG is used as a binder, the cycling performance of the Si anode is greatly improved. After one hundred cycles at an applied current density of 1 A g-1, the electrode continues to display remarkable electrochemical properties with a significant cyclic capacity (2213mAh g-1) and initial Coulombic efficiency (ICE) of 89.7%.

Enhanced Silicon Anodes with Robust SEI Formation Enabled by Functional Conductive Binder

AbstractThe application of silicon (Si) anode is limited by the drastic volume change of silicon in the lithiation/delithiation process, the repeated formation of the solid electrolyte interface (SEI), and the low intrinsic conductivity. In this work, a small amount of poly (3,4‐ethylenedioxythiophene):poly (styrene sulfonic acid) (PEDOT:PSS) (PP), citric acid (CA), isopropyl alcohol (IPA), and silicon nanoparticles (SiNPs) are mixed and vacuum treated at a specific temperature to obtain silicon‐based anode electrode composite Si@PP@CA. The interphase forms a robust elastic network with hydrogen and chemical bonds, which have good mechanical properties and self‐repairing characteristics. The modified PEDOT:PSS as the conductive medium significantly improves the charge transfer rate. Moreover, the rapid formation of SEI by CA on the surface of SiNPs enhances the structural stability of the material. The electrochemical results show that the capacity of Si@PP@CA composite electrode canretain more than 2200 mAh g−1 after 200 cycles at 0.2 A g−1. It still shows a high capacity retention of 89% even at the current density of 1.0 A g−1 after 2000 cycles. More importantly, such excellent performance can be obtained using an electrode with an active material content of up to 90 wt%, which is essential for practical applications.

Multi-layer wrapping functionalized silicon via graphene aerogels regenerated from spent graphite anode achieves high efficient lithium storage

The large volume expansion and severe pulverization of silicon nanoparticles (SiNPs) during cycling have significantly hindered its application into lithium-ion batteries (LIBs). Graphene, for its excellent mechanical strength and high conductivity, has been widely applied to alleviate the swelling effect and enhance the ion conductivity of electrode materials. Herein, a facile and low-cost method to wrap Si by graphene aerogels with multiple shells is proposed in this work. Specifically, graphene oxide (GO) is synthesized by an improved Hummers’ method with waste graphite anode as raw material, the surface of SiNPs are modified with an amino group to achieve electrostatic attraction with an abundant carboxyl group on GO. Then a two-step reduction is carried out to synthesize a 3D graphene aerogel structure with uniformly distributed SiNPs, the inner rGO shell enhances the transport of ions on the surface of Si, the outer shell provides excellent confinement against the volume expansion during battery cycling.

Facile coating strategy of Si/C composite anode for high-performance lithium-ion battery

Attributed to its high capacity by alloying with lithium, silicon is considered to be new generation of anodes that can replace graphite and receives much attention. Alleviating the electrode failure caused by volume expansion during lithiation and shrink during delihiation in silicon anodes plays a pivotal role in promoting the industrial application of silicon anodes. In this article, we proposed a facile carbon coating strategy on the surface of silicon nanospheres to buffer the stress during charge and discharge. By controlling the low molecular weight, an ethanol-soluble phenolic resin was synthesized and further self-assembled on the surface of silicon nanoparticles to form the precursor. Uniform Si/C composites were fabricated via pyrolysis. Diffraction of x-rays confirmed that the silicon retained the pristine crystalline structure. Scanning electron microscopy revealed a homogeneous wrap of the amorphous carbon layer on the superficies of the silicon. The galvanostatic charge-discharge test proved the excellent durability of Si/C anodes. Undergoing 50 cycles of galvanostatic lithiation/delithiation at 0.2C, the retention capacity was 96%, as high as 800 mAh/g. This facile but efficient strategy is compatible with large-scale production and improves the feasibility of the practical application of silicon-based anodes.

Optimization of the kinetics of siRNA desorption from the surface of silicon nanoparticles

Oncological diseases are one of the most significant medical and social diseases in most countries of the world. Over the past decades, the search and development of new drugs, treatment regimens and methods of molecular diagnostics of malignant neoplasms remains relevant. In turn, an important goal of molecular genetic research is to suppress the expression of genes responsible for the development of tumors. The key targets taken into account in the development of antitumor drugs are proteins involved in carcinogenic changes in the cell. One of the promising molecular targets for the development of medicinal compounds in targeted therapy of tumor diseases is poly(ADP-ribose)polymerase 1 (PARP1). A potential way to inhibit PARP1 even at the stage of protein translation is RNA interference due to small interfering RNAs (siRNAs). For the penetration of siRNAs into the target cell, it is necessary to develop a method of their transportation controlled in space and time. An actual direction for solving this problem is the use of highly stable porous silicon-based nanoparticles. In the current study, in order to increase the functionality of nanoparticles, their surface was modified with various agents (functionalization), providing increased efficiency of drug loading and more uniform release.

A Design Strategy of Carbon Coatings on Silicon Nanoparticles as Anodes of High-Performance Lithium-Ion Batteries

Carbon coatings are commonly used to improve the performance of silicon anodes by providing a conductive shell that discourages the formation of excess solid/electrolyte interphase (SEI). Lack of understanding on the links between the properties of carbon components, such as mechanical properties and conductivity, and the electrochemical properties limits the advances in development of high-performance silicon–carbon nanocomposites. Herein, uniform carbon coatings with different degrees of graphitization were formed on the surface of silicon nanoparticles using bitumen as a carbon precursor. Analysis of electrochemical impedance spectroscopy (EIS) and distribution of relaxation time (DRT) shows that the carbon coating of higher elasticity and high Li+ diffusion coefficient through the control of carbonizing bitumen coatings on silicon nanoparticles greatly enhanced the electrochemical performance of carbon-coated silicon anodes. The high elasticity provides stable contacts between silicon and carbon coatings and maintains a stable electrode/electrolyte interface (without excessive SEI growth) during long-term cycling. Compared with electronic conductivity, the efficiency of ion diffusion in the carbon coating is found to play an important role in the rate capability of the electrode. This work provides a design strategy to further optimize the performance of the silicon-based anodes.

Ratiometric detection of transcription factor based on Europium(III) complex-doped silicon nanoparticles and a G-quadruplex-selective Iridium(III) complex

To sensitively detect transcription factor (TF) in complicated biological systems, a ratiometric luminescent detection system based on europium(III) complex-doped silicon nanoparticles (SiNPs) and a G-quadruplex (G4)-selective iridium(III) complex has been successfully constructed. During the biosensor fabrication, the G-rich hairpin DNA H1 was immobilized on the surface of SiNPs which was doped with the europium(III) complex Eu(III)(EDTA)(DPA). The dsDNA (S1/S2) contains TF recognition site, and one of its ssDNA S2 is protected by TF from the digestion of exonuclease III (Exo III). The survived S2 starts a signal amplification process at the aid of Exo III, then a lot of G4 DNA was generated which can be recognized by the G4-selective iridium(III) complex (Ir(III)-2G). So, the emission intensity of Ir(III)-2G is enhanced with the increase of TF concentration, while the emission of Eu(III)(EDTA)(DPA) keeps stable. Ascribed to the long lifetimes of both metal complexes, the constructed detection platform can perform time-resolved emission spectroscopy (TRES) measurement in complicated biological systems. The ratiometric TF detection platform not only can detect NF-κB P50 in buffered system in the linear range of 0.05–5 nM with the limit of detection (LOD) 0.014 nM, but also is able to monitor NF-κB P50 in 10% human serum in the linear range of 0.05–5 nM with the LOD of 0.010 nM through TRES measurement. The two-metal complex-based ratiometric TF biosensor provides new strategy for low concentrations of biomarker detection in the complicated biological systems.

Constructing an artificial boundary to regulate solid electrolyte interface formation and synergistically enhance stability of nano-Si anodes

Low coulombic efficiency and poor cyclic stability are two common problems for silicon anodes. Therefore, it is of great significance to improve cycling performance and initial coulombic efficiency (ICE) via rational surface engineering on nano-Si anodes. Herein, a new nano-silicon anode is obtained by straightforward constructing a multifunctional polypyrrole protective layer on the surface of silicon nanoparticles, which is further used as the inner boundary of solid electrolyte interface (SEI) film. Specifically, the Li salt decomposition reaction between the electrolyte and silicon surface is effectively inhibited under the protection of the compact artificial boundary. The transfer of Li+ for forming the SEI film is selectively slower than that of lithiation/delithiation reaction. This further reduces the amount of SEI film, leading to a high ICE of 93.2% at 0.5 A g−1 for modified nano-Si anodes. In addition, the flexible SEI precursor combined with the high proportion of organic components in SEIs not only accommodates the volume change of nano-silicon, but also suppresses accumulation of “waste SEI”, so the electrode can maintain a reversible capacity of 1153.2 mAh g−1 at 1 A g−1 after 500 cycles. This work provides important guidance for surface structural optimization of alloy-type anodes with high volume change.

Synthesis and characterization of organic ligand capped luminescent silicon nanoparticles

The confinement effects on the optical characteristics of silicon nanoparticles (Si-NPs) are very attractive for a variety of low-cost applications of this nontoxic material in light emitting devices and photovoltaics. However, effective utilization of these properties in devices have been limited as chemically prepared Si-NPs are highly prone towards oxidation to form amorphous silica. Surface modified luminescent Si-NPs are synthesized by an inexpensive wet-chemical solution-based route by hydrolyzing the silicon tetrachloride (SiCl4) and terminating the Si dangling bonds by using different capping ligands. Structural, optical and electrical properties are studied and the photoluminescence (PL) characteristics are correlated to its core–shell structure. The photoluminescence characteristics of the surface modified Si-NPs of virtually identical sizes in the core was accounted in terms of effects from the variations in the cell-structure on the surface of Si-NPs introduced by changes in the nature of siloxane capping.

SnS nanoparticles as an artificial solid electrolyte interphase and effective conductive additive in silicon anodes

Using a simple hydrothermal method, we developed a Si@SnS anode material with SnS nanoparticles uniformly attached to the surface of silicon nanoparticles. Utilizing the first charge-discharge reaction mechanism of SnS, combined with the artificial solid electrolyte interphase to improve the solid electrolyte interphase stability of silicon-based materials and the introduction of conductive additives to improve the conductive properties of silicon-based materials, the Si@SnS material exhibits very excellent performance when applied to lithium-ion battery anodes. At a current density of 0.5A.g−1,after two cycles, the overall resistance of the Si@SnS material battery is reduced by nearly 55% relative to the resistance of the pure silicon battery. As a half-cell anode material, the first coulombic efficiency of Si@SnS at a current density of 1A.g−1 reached 85%, and after 200 cycles, it provided a reversible capacity of 1790 mAh.g−1 and a capacity retention rate of 74.6%.

Carbon Coating on Silicon for High-Performance Anode in Lithium-Ion Batteries

Silicon has attracted tremendous research interest as the next-generation anode material for lithium-ion batteries (LIBs) due to its approximately 10-fold higher capacity comparing to the graphite anode that is currently dominating the LIB market. Nevertheless, a critical drawback of silicon material is the dramatic volume change (>300%) during the lithiation and delithiation processes, which is a devastating destabilization factor for the silicon anode in battery cycling. Carbon coatings can serve as rigid framework to accommodate the volume change of silicon, to increase the conductivity of the silicon materials, and to protect the silicon surface from undesired side reactions. Here, we report two types of conductive carbon coatings on silicon materials through i) graphitization of a π-π stacking precursor poly(1-pyrenemethylmethacrylate) on SiO surface to encapsulate the SiO at a mild temperature, and ii) pyrolysis of polyvinylidene chloride precursor on silicon nanoparticle surface with stoichiometric ratio of sacrificial H and Cl elements that facilitate complete carbonization of the precursor. In addition, extended two‐phase transformation of carbon‐coated Si nanoparticles during electrochemical processes is examined.

Artificial Solid Electrolyte Interphase Formation on Si Nanoparticles through Radiolysis: Importance of the Presence of an Additive

In the context of energy transition, irradiation is a powerful tool to mimic quickly the modification of electrode materials upon charge/discharge cycles in lithium-ion batteries. In this study, the evolution of the surface of silicon nanoparticles upon irradiation in two electrolytes, containing or not fluoroethylene carbonate (FEC), was studied. In the presence of FEC, irradiation leads to the formation of a homogeneous layer of a few nanometers thick, covering the whole surface of the nanoparticles. The formation of an artificial solid electrolyte interphase (SEI) layer through radiolysis is thus achieved. Without FEC, only patches of degradation products are formed on the nanoparticle surfaces for the same irradiation dose. In the absence of FEC, LixPFyOz salts are formed. In the presence of FEC, LixPOy, LiF, and Si–F bonds are generated. In both cases, the interphase contains Li2CO3 and a polymer containing ethylene carbonate units. Slightly different polymers are formed at the surface of nanoparticles in the presence or absence of FEC, i.e., more cross-linked in the former case. The elastomeric properties of the polymer formed in the presence of FEC are thought to be responsible for the formation of the homogeneous layer on the Si surfaces, leading to the generation of an artificial solid SEI through the radiolysis process. This SEI, however, prevents the efficient transfer of Li+ ions, and more work is required to optimize its intrinsic (electro)chemical properties.

Tailoring the Surface of Silicon Nanoparticles for Enhanced Chemical and Electrochemical Stability for Li-Ion Batteries

Organic monolayers of epoxy-containing oligo(ethylene oxide)s were grafted to the surface of silicon nanoparticles via a hydrosilylation reaction. The surface functional groups suppressed the chemi...

Use of silicon nanoparticle surface coating in infection control: Experience in a tropical healthcare setting.

A nano-scale surface coating containing silicon nanoparticles (Bacterlon®) creates a hydrophobic surface which prevents the growth of bacteria. Study objective was to evaluate the performance of this silicon nano-coating in Sri Lankan healthcare setting. This prospective study was conducted from September 2015 to December 2015 in an Intensive Care Unit and a medical ward in Base Hospital Homagama and a bacteriology laboratory in Medical Research Institute, Colombo, Sri Lanka. Silicon nanoparticle coating was applied to 19 high touch surfaces from those three sites. During the follow-up period, these test sites and non-coated control sites were used for routine work and were cleaned routinely as per institute protocol. Swabbing was done for coated and non-coated sites once a week for 12weeksat unannounced times. Surfaces were categorized in to low (≤10CFU/cm2) and high (>10-99CFU/cm2) contamination by Aerobic Bacterial Count (ABC) in non-coated sites at any given time. In low and high contaminated surfaces, an improvement in the mean percentage bioburden reduction from 36.18% to 50.16% was observed from 4th week to 12th week with silicon nanoparticles and a significant reduction (p<0.05) was seen in ABC in each of the coated surface compared with their non-coated counterpart by the 12th week. The frequency of isolation of Acinetobacter spp. on coated surfaces had a significant reduction (p<0.01). Silicon nanoparticle coating demonstrates a significant reduction of the bacterial bioburden in low and high contaminated surfaces for 12 weeks in a tropical healthcare setting.

Functionalized silicon nanoparticles as fluorescent probe for detection of hypochlorite in water

In this work amine functionalized silicon nanoparticles colloid is utilized to prepare a fluorescent probe for detecting low concentration levels of hypochlorite in water. The sensor is prepared by adding organosilane in silicon nanoparticles colloidal solution which freshly synthesized by laser ablation of silicon target in distilled water. The amine-terminated surface of silicon nanoparticles is confirmed using Fourier transform infrared, UV–vis absorption spectroscopy and transmission electron microscopy methods. The photoluminescence measurements of the functionalized silicon nanoparticles colloid exhibit high photostability and good reproducibility making them ideal fluorescent probes for sensing applications. It shows high sensitivity, excellent selectivity and rapid response (˜6 min) toward hypochlorite. The room temperature fluorescent sensor detects hypochlorite of water in the linear concentration range from 1 to 5 μM with a 0.2 μM detection limit. The sensor properties including high sensitivity, fast response and facile synthesis of the amine-functionalized silicon nanoparticles are compared with other reports in literature for fluorescent detection of hypochlorite in water.

Surface Modification of Silicon Nanoparticles by an "Ink" Layer for Advanced Lithium Ion Batteries.

Owing to its high specific capacity, silicon is considered as a promising anode material for lithium ion batteries (LIBs). However, the synthesis strategies for previous silicon-based anode materials with a delicate hierarchical structure are complicated or hazardous. Here, Prussian blue analogues (PBAs), widely used in ink, are deposited on the silicon nanoparticle surface (PBAs@Si-450) to modify silicon nanoparticles with transition metal atoms and a N-doped carbon layer. A facile and green synthesis procedure of PBAs@Si-450 nanocomposites was carried out in a coprecipitation process, combined with a thermal treatment process at 450 °C. As-prepared PBAs@Si-450 delivers a reversible charge capacity of 725.02 mAh g-1 at 0.42 A g-1 after 200 cycles. Moreover, this PBAs@Si-450 composite exhibits an exceptional rate performance of ∼1203 and 263 mAh g-1 at current densities of 0.42 and 14 A g-1, respectively, and fully recovered to 1136 mAh g-1 with the current density returning to 0.42 A g-1. Such a novel architecture of PBAs@Si-450 via a facile fabrication process represents a promising candidate with a high-performance silicon-based anode for LIBs.

Measuring Dopant-Modulated Vibrational Energy Transfer over the Surface of Silicon Nanoparticles by 2D-IR Spectroscopy

2D-IR spectroscopy was used to characterize the vibrational dynamics of surface hydride modes on silicon nanoparticles (SiNPs). Energy transfer was compared between undoped (intrinsic) SiNPs and particles that were doped with boron and phosphorus. FTIR spectra reported changes in the relative proportions of Si–H, Si–H2, and Si–H3 populations when boron and phosphorus atoms were incorporated, while 2D-IR spectroscopy revealed that there was vibrational energy transfer on the tens of ps time scale between all three mode types for intrinsic SiNPs. This energy transfer was severely diminished by including just 0.05 atomic % of boron and was completely extinguished for 2.5 atomic % of phosphorus. In addition, the vibrational lifetimes of mono and polyhydride modes on intrinsic silicon particles were uniformly fast, while doped nanoparticles showed frequency dependent relaxation times reminiscent of porous and amorphous silicon films.

Highly sensitive and selective determination of copper(II) based on a dual catalytic effect and by using silicon nanoparticles as a fluorescent probe.

The authors describe a silicon nanoparticle-based fluorometric method for sensitive and selective detection of Cu2+. It is based on the catalytic action of Cu2+ on the oxidation of cysteine (Cys) by oxygen to form cystine and the by-product H2O2. The generated H2O2 is catalytically decomposed by Cu2+ to generate hydroxyl radicals which oxidize and destroy the surface of SiNPs. As a result, the blue fluorescence of the SiNPs is quenched. The method has excellent selectivity due to the dual catalytic effects of Cu2+, which is much better than most previously reported nanomaterial-based assays for Cu2+. Under the optimal conditions, the method has low detection limit (29nM) and a linear response in a concentration range from 0.05μM to 15μM. The method has been successfully applied to the determination of Cu2+ in spiked real water samples, and the results agreed well with those obtained by the Chinese National Standard method (GB/T 7475-1987; AAS). Graphical abstract Schematic presentation of a fluorometric method for the determination of Cu2+ based on the dual catalytic effects of Cu2+, and the oxidative effect of hydroxy radicals on the surface of silicon nanoparticles (SiNPs). The method has a 29 nM detection limit and good selectivity.

Controllable Growth of Core-Shell Nanogels via Esterase-Induced Self-Assembly of Peptides for Drug Delivery.

In this work, we developed an unexplored enzyme-responsive core-shell nanogel via the assembly of hydrogelators at the surface of silicon nanoparticles. The immobilized carboxylesterase at the surface of silicon nanoparticles can catalyse precursors into hydrogelators, self-assembling around the surface of silicon nanoparticles owing to its surface confinement effect. These novel phenomena can be confirmed by observation of their morphology and increased diameters through scanning electron microscopy, transmission electron microscopy and dynamic light scattering. Moreover, these resulting core-shell nanogels can achieve controlled growth of the gel layer by means of changing the concentrations of precursors. Because of their good biocompatibility, these nanogels can realize applications in enzyme-specific drug delivery as nanocarriers.

Hydrogen-assisted spark discharge generation of highly crystalline and surface-passivated silicon nanoparticles

The ability to produce highly pure and crystalline nanoparticles with prescribed surface chemistry is of vital importance as these properties play crucial roles in enhancing the performance of nanoparticle-embedded opto- and nano-electronic devices. In this study, we sought to improve the purity, crystallinity, and surface passivation of silicon nanoparticles as they are produced via spark discharge generation by introducing a hydrogen atmosphere. When pure argon is used as the carrier gas, we find that some particles are oxidized (silicon oxide rather than silicon) due to the trace amounts of oxygen present in the system, and those that are not oxides are often amorphous, as the spark energy is insufficient to produce highly crystalline silicon nanoparticles. When hydrogen is introduced into the chamber, it creates a reducing environment within the spark discharge zone, which effectively reduces the formation of oxide particles. The portion of generated silicon oxide nanoparticles decreases as more hydrogen is introduced into the system. In addition, hydrogen plasma generated from the spark discharge process improved the crystallinity of the produced silicon nanoparticles, and aids passivation of the silicon nanoparticle surface by forming Si-Hx bonds, enhancing their stability during handling in oxygen containing atmosphere. Thus, the presented technique can be used to produce hydrogen-passivated silicon nanoparticles with high purity and crystallinity, and it is expected that these particles can be utilized as quantum dots after size-selection or be incorporated into luminescence devices.