SiO2 Core Shell Research Articles

Magnetically recoverable nanoparticle organic hybrid materials as kinetic hydrate inhibitors

Gas hydrates pose significant risks in the oil and gas industry because of their tendency to form blockages in transportation pipelines under low-temperature and high-pressure conditions. Conventional thermodynamic hydrate inhibitors require high dosages, with associated substantial costs and environmental concerns. Kinetic hydrate inhibitors (KHIs), which operate at much lower dosages, offer a more sustainable solution but are often limited by environmental compatibility and recovery problems. In this study, we introduce a novel class of magnetically recoverable KHIs utilizing nanoparticle organic hybrid materials (NOHMs), named NOHM-I-PNIPAM, featuring a tunable Fe3O4 core-SiO2 shell structure with poly(N-isopropylacrylamide) (PNIPAM) as the organic component. The chemical properties of NOHM-I-PNIPAM were characterized using TEM, FT-IR, and XPS. The hydrate kinetic inhibition performance was evaluated with a CH4 (90 %) + C2H6 (7 %) + C3H8 (3 %). Various grafting densities of PNIPAM on NOHMs and weight fractions of NOHM-I-PNIPAM were used to explore NOHM-I-PNIPAM’s role in the formation kinetics of natural gas hydrates under different cooling rates. Notably, the NOHM-I-PNIPAM (1.0), when utilized at a 2 wt% dosage, exhibited the most effective inhibition performance in terms of the onset temperature of CH4 (90 %) + C2H6 (7 %) + C3H8 (3 %) hydrate. Considering the effective concentration of PNIPAM in NOHM-I-PNIPAM, the inhibition performance was found to be comparable to that of conventional PNIPAM. Results showed that NOHM-I-PNIPAM is a promising KHI due to its combined properties of magnetic separation and comparable kinetic inhibition performance. Experimentally, NOHM-I-PNIPAM demonstrated stability over long-term cycles and was effectively magnetically separated. Hence, we believe that this work can provide valuable insights into the potential of NOHMs as recoverable and reusable KHIs for industrial applications for flow assurance.

A Time-Interval Strategy to Prepare Porous SiO2 Spheres with Adjustable Core-Shell Ratio for Multiple Guest Loading.

Porous microspheres with desired pore size and distribution are in high demand for loading various guest materials, especially various pollutants that are several nanometers in size or stably suspended in liquid. Herein, multilevel porous SiO2 microspheres with arbitrarily adjustable core-shell ratios are prepared by solely regulating the time interval between the start of the hydrolysis reaction and the addition of organic solvent. The core-shell ratio of the SiO2 microspheres increases gradually with prolongation of the addition time interval; meanwhile, the specific surface area can be adjusted from 543.2 m2 g-1 to 992.9 m2 g-1, and the average pore diameter varies from 2.3 to 5.7 nm together with a high pore volume reaching 0.91 cm3 g-1. Moreover, the hierarchical core-shell SiO2 microspheres with an adjustable core-shell ratio, a large specific surface area, and a multilevel pore size could be obtained on a large scale. These SiO2 microspheres demonstrate excellent performance in coloading platinum nanoparticles and various dye molecules, suggesting their great potential in treating various pollutants in printing and dyeing wastewater.

Fabrication of Nano Porous Silicon Particle with SiO2 Core Shell for Lithium Battery Anode

Fabrication of Nano Porous Silicon Particle with SiO2 Core Shell for Lithium Battery Anode

Synthesis of ZrN–SiO2 core–shell particles by a sol–gel process and use as particle‐based structured coloring material

AbstractZrN–SiO2 core–shell particles were prepared, where the ZrN core nanoparticles and SiO2 shell were designed to exhibit localized surface plasmon resonances (LSPRs) and structural coloring. The heating of ZrO2 nanoparticles with Mg3N2 under a nitrogen gas flow produced ZrN nanoparticles with a diameter in the range of 10–20 nm. The dispersion of ZrN nanoparticles in water exhibited an absorption maximum at approximately 700 nm owing to LSPRs. An SiO2 shell was formed on the ZrN nanoparticles using a sol–gel process. Scanning transmission electron microscopy confirmed the formation of ZrN–SiO2 core–shell particles containing ZrN particles with a diameter of approximately 10 nm. The SiO2 shell thickness was controlled by varying the reaction time to form SiO2. The use of particles as a structural component of a structural color material owing to the high uniformity of the size of obtained core–shell particles was investigated. The obtained ZrN–SiO2 core–shell particles were arrayed on a glass substrate using a layer‐by‐layer method. The particle‐stacked film of the ZrN–SiO2 core–shell particles exhibited the maximum reflection depending on the particle size of the SiO2 shell.

Effect of structure of ZnO and SiO2 core-shell composite nanoparticles as lubricant additive on tribological properties of greases

Nano-additives can enhance the tribological properties of greases. In particular, core-shell composite nanoparticles, which combine multiple nanoparticles, have been the subject of recent research due to their superior properties. In this study, based on the friction pairs material, GCr15, by choosing ZnO with low hardness and SiO2 with high hardness, core-shell composite nanoparticles with soft shell hard core SiO2@ZnO and hard shell soft core ZnO@SiO2 were prepared by chemical deposition and calcination methods. The impact of different structural forms of these composite nanoparticles as grease additives were investigated for the first time by adding them into lithium grease. The results show that ZnO@SiO2 have good tribological properties under light load, reducing the COF by 18 % and decreasing the WSD by 22 %. SiO2@ZnO exhibit the best anti-friction effect under heavy load conditions, reducing the COF by 15 % and decreasing the WSD by 28 %. The GCr15-ZnO-SiO2 surface composite film structure is the key to improve the performance of grease in the two composite nanoparticles. It not only has good wear resistance, but also can increase the bearing capacity of the oil film. The two core-shell structure nano-additives provide a new idea for the design of lubricants under special conditions.

Confined MOF pyrolysis within mesoporous SiO2 core–shell nanoreactors for superior activity and stability of electro-Fenton catalysts

Despite the high density and uniform distribution of active sites in metal–organic frameworks (MOFs) and their derivatives, the relatively low stability in water still limits their utilization in heterogeneous catalysis. Herein, the confinement of pyrolyzed MIL-88B(Fe) derivatives within mesoporous SiO2 allowed fabricating core–shell nanoreactors (Fe/C@mSiO2) that served as heterogeneous electro-Fenton (HEF) catalysts for the first time, revealing an excellent performance. The as-prepared catalysts were featured by high specific surface area and dense active sites. During service as core–shell nanoreactors, they behaved as a dual function adsorbent-catalyst, exhibiting superior catalytic activity and recyclability as compared to HEF catalysts without shell. Using 0.2 g/L of catalyst, the complete removal of bisphenol A at pH 6.2 and 100 mA was achieved at 120 min, with extremely low iron leaching of 0.11 mg/L. The rigid mSiO2 shell not only protected the iron active sites from leaching, but it also provided porous and permeable channels for efficient mass transport. The unique core–shell architecture concentrates the catalytic sites and reactants within a confined space, promoting the fast degradation of bisphenol A. Furthermore, the defect-rich carbon substrate and the high dispersibility of iron-rich sites favor a fast electron transfer. The efficient treatment of several organic micropollutants in consecutive trials corroborated the high activity and stability of the Fe/C@mSiO2. This work contributes to the rational design of HEF catalysts, aiming at consolidating their practical application in advanced wastewater treatment.

Investigation of structural, temperature and frequency dependent dielectric behavior of Zn2SnO4@amorphous SiO2 core shell nanocomposites

Herein, the detailed investigation of frequency and temperature dependent dielectric behavior of Zn2SnO4@SiO2 core shell nanocomposites (CSNs) is reported. Powder XRD analysis and FTIR spectral analysis were employed to comprehend the structure. The chemical and valence states are analyzed using XPS which confirms the existence of Zn, Sn, and SiO2, each with their distinctive Zn 2p, Sn 3d, and Si 2p valence states. The core shell formation is confirmed from their distinct color contrast in the TEM micrographs. The electrical response was investigated using impedance spectroscopy in the frequency range 1Hz-1 MHz at various temperatures. Positive temperature coefficient of resistance type behavior was established from impedance and modulus formalism. The total conductivity values were well fitted by the universal Jonscher law σtotal = σdc+ Aωn, and the temperature dependence of dc conductivity was discussed.

Anisotropy of photocatalytic properties of MoO3/TiO2–SiO2 core–shell polycrystalline composites

In this work, the effect of the preferred orientation of MoO3 crystals in polycrystalline MoO3/TiO2–SiO2 composites on their optical properties and photocatalytic activities in the decomposition reaction of organic dyes was investigated. The anisotropy of the photocatalytic properties was shown. The MoO3/TiO2–SiO2 core–shell spherical composites were prepared using TOKEM-320Y anion exchange resin as a template by the combined method, including template and sol–gel methods. The XRD, XPS, EDS, SEM, Raman, IR, DRS, N2 sorption, and PL techniques were used to characterize the elemental and phase compositions, textural and optical properties of the MoO3/TiO2–SiO2 spherical particles. The MoO3/TiO2–SiO2 composites prepared at 600 °C were characterized by the lowest anisotropy coefficient (1.23) of the crystals growth rate in the plane (l00) relative to the crystals growth rate in the plane (lll) and the highest concentration of oxygen vacancies. High temperature treatment of MoO3/TiO2–SiO2 samples up to 700 °C leads to a change in the degree of their texture, which is due to the growth of the anisotropy coefficient up to 1.38 and crystallites in the (l00) plane, which was confirmed by increasing the Lotgering factor. The content of Mo5+ in the surface and subsurface layers of such composites is the highest. The MoO3/TiO2 − SiO2 composites prepared at 600 °C exhibited a much higher photocatalytic activity (the rate constant is 0.0319 min-1). This work demonstrates that the predominant orientation of MoO3 crystals in the (l00) plane negatively affects the oxygen defect (the value decreases to 0.0486) and MoO3/TiO2 − SiO2 polycrystalline composites photocatalytic activity.

Difunctional Ag nanoparticles with high lithiophilic and conductive decorate on core-shell SiO2 nanospheres for dendrite-free lithium metal anodes

Lithium metal is an attractive and promising anode material due to its high energy density and low working potential. However, the uncontrolled growth of lithium dendrites during repeated plating and stripping processes hinders the practical application of lithium metal batteries, leading to low Coulombic efficiency, poor lifespan, and safety concerns. In this study, we synthesized highly lithiophilic and conductive Ag nanoparticles decorated on SiO2 nanospheres to construct an optimized lithium host for promoting uniform Li deposition. The Ag nanoparticles not only act as lithiophilic sites but also provide high electrical conductivity to the Ag@SiO2@Ag anode. Additionally, the SiO2 layer serves as a lithiophilic nucleation agent, ensuring homogeneous lithium deposition and suppressing the growth of lithium dendrites. Theoretical calculations further confirm that the combination of Ag nanoparticles and SiO2 effectively enhances the adsorption ability of Ag@SiO2@Ag with Li+ ions compared to pure Ag and SiO2 materials. As a result, the Ag@SiO2@Ag coating, with its balanced lithiophilicity and conductivity, demonstrates excellent electrochemical performance, including high Coulombic efficiency, low polarization voltage, and long cycle life. In a full lithium metal cell with LiFePO4 cathode, the Ag@SiO2@Ag anode exhibits a high capacity of 133.1 and 121.4 mAh/g after 200 cycles at rates of 0.5 and 1C, respectively. These results highlight the synergistic coupling of lithiophilicity and conductivity in the Ag@SiO2@Ag coating, providing valuable insights into the field of lithiophilic chemistry and its potential for achieving high-performance batteries in the next generation.

Preparation and performance of laminated anti‐fire glass using the K2O·nSiO2‐based ultrathin and flexible membrane

AbstractWe present a new method for synthesizing cold‐resistant laminated anti‐fire glass using a K2O·nSiO2‐based ultrathin flexible membrane, which is prepared by vacuum surface treatment method with ball‐milled core–shell SiO2 emulsion (55 wt%). We systemically characterize the mechanical, optical, rheological, cold‐resistant, fire‐resistant, and weather‐resistant performances of this glass. The formation mechanism of K2O·nSiO2‐based ultrathin membrane is studied in detail using multispeckle diffusing–wave spectroscopy and scanning electron microscopy. Then, the tensile strength, plasticity, and rheological behavior of the materials with different moduli are characterized. Combined with thermal gravity analysis, we characterize the compositions of K2O·nSiO2‐based materials with different moduli. For the K2O·nSiO2‐based ultrathin flexible membrane, the appearance of air‐conducting microchannels is designed, resembling the Wu Zhu coin morphology (a square hole circular coin in ancient China) or honeycomb wall morphology. These structures endow the visible region of the anti‐fire glass with a reduced presence of microbubbles. As a type of building safety glass, the spongelike microporous insulation layer can increase the heat‐insulating time in the event of a fire. Furthermore, the weather‐resistant performance of this glass is demonstrated to be more than 3000 h through an ultraviolet test. This work also provides a new routine for synthesizing high‐quality anti‐fire glass with different shapes, including curved surfaces.

Design of CuO @ SiO2 core shell nanocomposites and its applications to photocatalytic degradation of Rhodamine B dye

In this work, photocatalytic behavior of CuO@SiO2 core shell nanocomposites (CuO@SiO2 CSNs) is reported. The formation and structure of the prepared samples were confirmed using powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and High resolution transmission electron microscopy (HRTEM) techniques. UV analysis revealed that the incorporation of SiO2 onto CuO resulted in a notable decrease in the bandgap energy from 3.2 eV to 2.8 eV, along with a reduction in the rate of electron-hole recombination and in consequence of that CuO@SiO2 CSNs demonstrated an impressive degradation rate of 92% for Rhodamine B (Rh B), while CuO Nanoparticles (NPs) exhibited a relatively lower rate of 80%. The BET surface area analysis revealed that CuO@SiO2 CSNs had a greater surface area of 68.418 m³/g as opposed to 9.364 m³/g for CuO NPs, which contributed to the former's remarkable catalytic performance.

Design of SiO x /TiO2@C hierarchical structure for efficient lithium storage

The large volume expansion effect and unstable solid electrolyte interface films of SiO x -based anode materials have hindered their commercial development. It has been shown that composite doping is a general strategy to solve critical problems. In this study, TiO2-doped core–shell SiO x /TiO2@C composites were created using the sol–gel method. On the one hand, the uniformly dispersed TiO2 nanoparticles can alleviate the volume expansion of the SiO x active material during the lithiation process. On the other hand, they can react with Li+ to form Li x TiO2, thereby increasing the ion diffusion rate in the composite material. The outer carbon shell acts as a protective layer that not only alleviates the volume expansion of the composite, but also improve the electron migration rate of the composite. The prepared SiO x /TiO2@C composite has a reversible capacity of 828.2 mA h g−1 (0.2 A g−1 100 cycles). After 500 cycles, it still maintains a reversible capacity of 500 mA h g−1 even at a high current density of 2 A g−1. These findings suggest that SiO x /TiO2@C composites have a bright future in applications.

Design of core-shell SiO2 nanoparticles to create anti-reflection and anti-fouling coatings for solar cells

Amphiphobic coatings with the anti-reflective property offer a promising strategy to mitigate the degradation of photovoltaic conversion efficiency in solar cells caused by fouling and reflection of incident light. Despite advancements in developing transparent and liquid-repellent coatings, achieving integration of both properties still poses a significant challenge. In this work, a unique nanostructure coating with extremely low roughness and surface energy is constructed by integrating fluorinated cluster core-shell structured silicon sols (BASSF) into a self-made silicon precursor (SP) using a template-free two-step base/acid-catalyzed reaction. The exceptional anti-fouling performance of the S-P@BASSF coating is a result of the chemical inertness of the polymer and the unique structure of the sol-gel particles. This innovative approach provides a potential solution for fabricating high-performance coatings and materials. The coating is capable of recovering to 97 % of its initial efficiency swiftly, even after severe dust contamination. The coating exhibits remarkable anti-reflective property due to the combination of sol particles with varying refractive indices. The coating also displays high weathering resistance, maintaining contact angles with water (≥105°) and diiodomethane (≥85°) even after prolonged exposure to UV lamps, high temperature and high humidity weather. The results obtained in this study show that nanocomposite coatings via the preparation of smooth, high refractive index and low reflectivity have great potential for outdoor applications such as energy harvesting and optical instruments under wet conditions.

Oxygen vacancies enriched Ni-Co/SiO2@CeO2 redox catalyst for cycling methane partial oxidation and CO2 splitting

Redox catalysts play a vital role in the interconversion of two significant greenhouse gases, CO2 and CH4, via chemical looping methane dry reforming technology. Herein, a series of transition metals-alloyed and core–shell structured Ni-M/SiO2@CeO2 (M = Fe, Co, Cu, Mn, Zr) redox catalyst were fabricated and evaluated in a gas–solid fixed-bed reactor for cycling CH4 partial oxidation (POx) and CO2 splitting. The catalysts are composed of spherical SiO2 core and CeO2 shell, and the highly dispersed Ni alloy nanoparticles are the interlayer between core and shell. The oxygen vacancy concentration of Ni-M/SiO2@CeO2 followed the order of Co > Cu > Fe > Mn > Zr, and Ni alloying with transition metals significantly enhanced oxygen storage capacity (OSC). Ni-Co/SiO2@CeO2 catalyst with abundant oxygen vacancies and a high OSC showed the lowest temperatures of CH4 activation (610 °C) and CO2 decomposition (590 °C), thus demonstrating excellent redox reactivity. The catalyst exhibited superior activity and structural stability in the continuous CH4/CO2 redox cycles at 615 °C, achieving 87% CH4 conversion and 83% CO selectivity. The proposed catalyst shows great potential for the utilization of CH4 and CO2 in a redox mode, providing a new sight for design redox catalyst in chemical looping or related fields.

Core-shell metal-organic framework/silica hybrid with tunable shell structure as stationary phase for high performance liquid chromatography

Metal-organic framework/silica composite (SSU) were prepared by growing UiO-66 on the amino-functionalized SiO2 core-shell spheres (SiO2@dSiO2) via a simple one-pot synthesis approach. By controlling the concentration of Zr4+, the obtained SSU have two different morphologies: spheres-on-sphere and layer-on-sphere. The spheres-on-sphere structure is formed by the aggregation of UiO-66 nanocrystals on the surface of SiO2@dSiO2 spheres. SSU-5 and SSU-20, which contain spheres-on-sphere composites have mesopores with a pore size of about 45 nm in addition to the characteristic micropores of UiO-66 with a pore size of 1 nm. In addition, UiO-66 nanocrystals were grown both inside and outside the pores of SiO2@dSiO2, resulting in a 27% loading of UiO-66 in the SSU. The layer-on-sphere is the surface of SiO2@dSiO2 covered with a layer of UiO-66 nanocrystals. SSU with this structure has only a characteristic pore size of about 1 nm belonging to UiO-66 and is therefore not suitable as a packed stationary phase for high performance liquid chromatography. The SSU spheres were packed into columns and tested for the separation of xylene isomers, aromatics, biomolecules, acidic and basic analytes. With both micropores and mesopores, SSU with spheres-on-sphere structure achieved baseline separation of both small and large molecules. Efficiencies up to 48,150, 50,452 and 41,318 plates m − 1 were achieved for m-xylene, p-xylene and o-xylene, respectively. The relative standard deviations of the retention times of anilines for run-to-run, day-to-day and column-to-column were all less than 6.1%. The results show that the SSU with spheres-on-sphere structure has great potential for high performance chromatographic separation.

Applicability of core-shell SiO2 microspheres with a high TiO2 loading as stationary phase for HPLC

BackgroundDue to its high chemical stability, sufficient rigidity and zwitterionic ion exchange properties, TiO2 can be considered as an alternative stationary phase material to SiO2 for high performance liquid chromatography. TiO2 stationary phase is usually prepared by coating TiO2 onto SiO2 support by sol-gel method. However, in the traditional coating method, in order to overcome the rapid hydrolysis rate of tetrabutyl orthotitanate, only a very low concentration of tetrabutyl orthotitanate can be used, resulting in a low loading of TiO2 on the support. ResultsTiO2 core-shell spheres with a good monodispersity were prepared using 0.25 mol L−1 tetrabutyl orthotitanate. The specific surface area, pore volume, pore diameter and TiO2 loading of the TiO2 core-shell spheres were 66 m2 g−1, 0.15 cm3 g−1, 9.8 nm and 57%, respectively. The core-shell spheres were derivatized with n-octadecyltrichlorosilane and then packed into a stainless steel column to test the separation performance for neutral, basic and acidic samples in liquid chromatography. A baseline separation of polyaromatic hydrocarbons was achieved, showing a column efficiency for fluorene of 118075 plates m−1. The prepared stationary phase was also used to separate acidic and basic mixtures, and column efficiencies of 54500 and 25836 plates m−1 were obtained for N,N-dinitroaniline and p-chlorophenol, respectively. The relative standard deviations of the retention times of polyaromatic hydrocarbons for run-to-run, day-to-day and column-to-column repeatability were all below 5.1%. Significance and noveltyThis work demonstrated that TiO2 can be coated in the pores of the shell of SiO2 core-shell spheres with high TiO2 loading using a high concentration of tetrabutyl orthotitanate as the titania source. The experimental results show that the TiO2 coated core-shell spheres can be a good alternative stationary phase for liquid chromatography.

Simple Preparation Method of Silica Core–Shell Spheres for HPLC in Undergraduate Chemistry

High-performance liquid chromatography (HPLC) experiments are an important part of the undergraduate analytical instrumentation laboratory courses and usually use commercial C18 silica-packed reversed-phase columns. In this experiment, a simple method of preparing SiO2 core–shell packed columns was developed to enable students to master the whole process of HPLC experiment from stationary phase preparation and column packing to separation experiments, just as they do for gas chromatography. Nonporous SiO2 particles with a particle size of approximately 2.2 μm were prepared by a three-step dilution reaction using the sol–gel method. The product yield was 92.1%. Monodisperse and spherical SiO2 core–shell particles (SiO2@dSiO2) with a particle size of about 2.4 μm were prepared by a one-step hydrothermal method using the prepared SiO2 spheres as the core. The product yield was 83.3%. The prepared SiO2@dSiO2 particles were derivatized with n-octadecyldimethylchlorosilane and then packed into a stainless steel chromatography column. A high column efficiency of 83,188 theoretical plates per meter was obtained for fluorene in reversed-phase mode for the separation of a mixture of polycyclic aromatic hydrocarbons. The column efficiency obtained with this method is the same as that of a commercial column packed with fully porous particles of the same particle size. The SiO2 core–shell stationary phase preparation method developed in this experiment has the advantages of simple process, high yield, and good repeatability. The experiment can be designed to be completed over a period of 1–3 weeks. Inorganic material synthesis is another important aspect of this experiment.

Blocking polysulfide by physical confinement and catalytic conversion of SiO2@MXene for Li–S battery

Lithium–sulfur (Li–S) batteries have attracted increasing attention for next-generation energy storage systems with a high energy density and low cost. However, the practical applications have been plagued by the sluggish reaction kinetics and the shuttle effect of lithium polysulfides (LiPSs). Herein, core–shell SiO2@Ti3C2Tx MXene (SiO2@MX) hollow spheres are constructed as multifunctional catalysts to boost the performance of Li–S batteries. The dual-polar and dual-physical properties of SiO2 core and MXene shell provide multiple defense lines to the shuttle effect by chemical and physical confinement to LiPSs. Density functional theory calculations prove that Ti3C2Tx MXene and SiO2 enable the stronger trapping ability of LiPSs and the fast Li2S decomposition process. With this strategy, the robust SiO2@MX/S electrodes deliver superior electrochemical performances, including a high capacity of 1263 mAh g−1, and remarkable cycling stability with an ultralow capacity decay of 0.04% per cycle over 1000 cycles at 1 C. This work highlights the significance of core-shell dual-polar structural sulfur catalysts for practical application in advanced Li–S batteries.

Convenient hydrothermal treatment combining with “Ship in Bottle” to construct Yolk-Shell N-Carbon@Ag-void@mSiO2 for high effective Nano-Catalysts

More active sites will be exposed when noble metal particles are loaded on the core of yolk-shell nanospheres (NM-YSNS) to give higher metal utilization rate, catalytic activity, and good recycle stability. Herein, we adopt an efficient strategy to access the high-performance NM-YSNS via “ship in bottle” mindset on loading Ag nanoparticle on the core surface of core–shell structure accurately and the core shrinkage on forming yolk-shell structure. First, we systematically investigated the mechanism of SiO2 coating 3-aminophenol-co-formaldehyde nanoparticles to generate 3-aminophenol-co-formaldehyde@mesoporous SiO2 core–shell nanospheres (3-APF@mSiO2 CSNS). Interestingly, the core surface of 3-APF@mSiO2 CSNS became uneven after hydrothermal process, which provided positions for Ag, then additional Ag+ could reach the 3-APF surface through the mSiO2 shell and be in situ reduced into Ag particles by –NH- and –NH2 there. Similarly, the 3-APF@Au@mSiO2 CSNS were prepared successfully. After carbonizing 3-APF@Ag@mSiO2 CSNS, the N-Carbon@Ag-void@mSiO2 YSNS was obtained. The NM-YSNS catalyst had a high specific surface area of 258.8 m2g−1, mSiO2 shell of 3.8 nm mesoporous size, and core loaded with Ag particles firmly, showing a high turnover frequency of 137.08 h−1 and good recycle stability in catalytic reduction of 4-nitrophenol for preparing 4-aminophenol.

In Situ Coatings of Polymeric Films with Core Polystyrene, Core-Shell Polystyrene/SiO2, and Hollow SiO2 Micro/Nanoparticles and Potential Applications.

In many industrial settings, films of polymers such as polypropylene (PP) and polyethylene terephthalate (PET) require surface treatment due to poor wettability and low surface energy. Here, a simple process is presented to prepare durable thin coatings composed of polystyrene (PS) core, PS/SiO2 core-shell, and hollow SiO2 micro/nanoparticles onto PP and PET films as a platform for various potential applications. Corona-treated films were coated with a monolayer of PS microparticles by in situ dispersion polymerization of styrene in ethanol/2-methoxy ethanol with polyvinylpyrrolidone as stabilizer. A similar process on untreated polymeric films did not yield a coating. PS/SiO2 core-shell coated microparticles were produced by in situ polymerization of Si(OEt)4 in ethanol/water onto a PS-coated film, creating a raspberry-like morphology with a hierarchical structure. Hollow porous SiO2-coated microparticles onto a PP/PET film were formed by in situ dissolution of the PS core of the coated PS/SiO2 particles with acetone. The coated films were characterized by E-SEM, FTIR/ATR, and AFM. These coatings may be used as a platform for various applications, e.g. magnetic coatings onto the core PS, superhydrophobic coatings onto the core-shell PS/SiO2, and solidification of oil liquids within the hollow porous SiO2 coating.