Synthesis and Characterization of Poly (Methyl Methacrylate)/Polyethylenimine Grafting Core-Shell Nanoparticles for CO2 Adsorption Using Soap-Free Emulsion Copolymerization

Unlike previous emulsion polymerization, we used grafting reactions in soap-free emulsion systems. In this study, we synthesized grafted PMMA/PEI core-shell nanoparticles by varying the MMA/PEI content and molecular weight of PEI (Mn = 600, 8000, and 10,000). The size and morphology of the core-shell nanoparticles were characterized by a particle size analyzer and scanning electron microscopy. The nanoparticles were 178 - 408 nm in diameter and swelled in water or methanol by 30 - 75 nm. The size of the nanoparticles increased with MMA contents, whereas the size distribution progressively became homogeneous with increasing molecular weight of PEI. Lastly, we measured CO2 adsorption capacity of the grafted PMMA/PEI core-shell nanoparticles, and we found the capacity to be limited at a level of 0.69 mg, which occurred for nanoparticles prepared from emulsions at a pH value of 11.

PREPARATION OF POLYSTYRENE/SiO_2 COMPOSITE NANOPARTICLES BEARING SULFONIC GROUPS ON THE SURFACE VIA EMULSION COPOLYMERIZATION USING A POLYMERIZABLE EMULSIFIER

Functionalized PS/SiO_2 composite nanoparticles bearing sulfonic groups on the surface were successfully synthesized via emulsion copolymerization using a polymerizable emulsifierαolefin solfonate(AOS).As demonstrated by transmission electron microscopy and atomic force microscopy,well-defined core-shell PS/SiO_2 composite nanoparticles with a diameter of 50 nm were obtained.Sulfonic groups introduced onto the surface of the composite nanoparticles were quantified by FTIR,and can be controlled to some exten...

N-doped core-shell mesoporous carbon spheres embedded by Ni nanoparticles for CO_(2)electroreduction

Herein,we successfully prepare highly dispersed and uniform small nano-size nickel nanoparticles embedded on core-shell carbon spheres by confined-deposition method.The mesoporous silica layer containing surfactant coated on the surface of the polymer sphere provides confined space and effectively controls the growth of nickel nanoparticles during pyrolysis.At the same time,the introduction of nickel species has an impact on structure of the obtained carbon spheres,and it can promote the deposition of carbon to realize the adjustment from hollow to core-shell and then to solid spheres.Owing to the uniform distribution of Ni nanoparticles with small size,mesoporous structure,N-doping groups,high specified surface areas,and core-shell structure,the obtained catalyst shows exciting ability for the production of CO by reduction of CO_(2)with a maximum CO Faradaic efficiency of 98%,indicating its promising prospect in electro-reduction of CO_(2).

MoS_(2)core-shell nanoparticles prepared through liquid-phase ablation and light exfoliation of femtosecond laser for chemical sensing

Molybdenum disulfide(MoS_(2))-based nanostructures are highly desirable for applications such as chemical and biological sensing,photo/electrochemical catalysis,and energy storage due to their unique physical and chemical properties.In this work,MoS_(2)core-shell nanoparticles were first prepared through the liquid-phase processing of bulk MoS2by a femtosecond laser.The core of prepared nanoparticles was incompletely and weakly crystalline MoS_(2);the shell of prepared nanoparticles was highly crystalline MoS_(2),which wrapped around the core layer by layer.The femtosecond laser simultaneously achieved liquid-phase ablation and light exfoliation.The formation mechanism of the core-shell nanoparticles is to prepare the nanonuclei first by laser liquid-phase ablation and then the nanosheets by light exfoliation;the nanosheets will wrap the nanonuclei layer by layer through van der Waals forces to form core-shell nanoparticles.The MoS_(2)core-shell nanoparticles,because of Mo-S bond breakage and recombination,have high chemical activity for chemical catalysis.Afterward,the nanoparticles were used as a reducing agent to directly prepare three-dimensional(3D)Au-MoS_(2)micro/nanostructures,which were applied as surface-enhanced Raman spectroscopy(SERS)substrates to explore chemical sensing activity.The ultrahigh enhancement factor(1.06×10^(11)),ultralow detection limit(10-13M),and good SERS adaptability demonstrate highly sensitive SERS activity,great ability of ultralow concentration detection,and ability to detect diverse analytes,respectively.This work reveals the tremendous potential of 3D Au-MoS_(2)composite structures as excellent SERS substrates for chemical and biological sensing.

A Novel Electrogenerated Chemiluminescence Reaction Scheme Using Core-Shell LuminoI-Based SiO2 Nanoparticles as a Regulator and Its Analytical Application

A novel core-shell luminol-based SiO2 nanoparticle While these nanoparticles were used as electrogenerated was synthesized by two step micro-emulsion method. chemiluminescence （ECL） reagent, the electrochemical （EC） reaction as well as the subsequent chemiluminescence （CL） reaction not only could be separated spatially, but also presented high efficiency for analytical purpose. In this case, the core-shell luminol-based SiO2 nanoparticles offered more potential to avoid the contradiction between the EC and the CL reaction conditions. A new ECL method based on the nanoparticle was developed, and isoniazid was selected as a model analyte to illustrate the characteristics of this new ECL method. Under the selected conditions, the proposed ECL response to isoniazid concentration was linear in the range of 1.0 ×10^-10 to 1.0 × 10^-6 g/mL with 2 × 10^-11g/mL detection limit.

Dispersion behavior of core-shell silica-polymer nanoparticles

Core-shell silica nanoparticles are superior in modifying surface wetting behavior, enhancing nucleation and growth in crystallization, improving dispersion of naked nanoparticles, and thus upgrading the overall properties of organic polymers. The dispersion behavior and morphology of monodisperse core-shell silica particles in several polymers including polyesters are reviewed and their potential applications are discussed.

Dual-step hybrid SERS scheme through the blending of CV and MoS_(2) NPs on the AuPt core-shell hybrid NPs

Along with a wide range of applications,the surface-enhanced Raman spectroscopy(SERS)is a promi-nent analytical technique to recognize and detect molecules and materials even at an extremely low mo-lar concentration.In this work,a unique hybrid SERS platform is demonstrated by the incorporation of molybdenum disulfate(MoS_(2))nanoparticles(NPs)onto the core-shell AuPt hybrid NPs(HNPs)for the en-hanced molecular Raman vibration of crystal violet(CV).The hybrid platform takes the advantage of both the electromagnetic mechanism(EM)offered by the AuPt HNPs and chemical mechanism(CM)owing to the MoS_(2)NPs.The distinctive core-shell morphology of AuPt HNPs with the high-density background Au NPs is attained by a unique two-step solid-state dewetting method,which can offer a high concentration of electromagnetic hot spots.At the same time,the MoS_(2)NPs can provide an ample charge transfer with abundant active sites.Through the hybrid SERS approach,a dramatic SERS enhancement of CV Raman vibration is demonstrated,and the SERS capability is thoroughly studied.In addition,the finite-difference time-domain(FDTD)simulations provide a deeper understanding of the electromagnetic field distributions for various configurations of nanostructures and their hybrid combinations:i.e.,HNPs,alloy NPs,MoS_(2)/HNPs configurations.

Mixed transition-metal oxides@carbon core-shell nanostructures derived from heterometallic clusters for enhanced lithium storage

Multicomponent binary metal oxide-involved hybrid structures with unique physicochemical properties have received extensive attention due to their fascinating electrochemical performance.Herein,a flexible strategy,which involves the preparation of dual-functional heterometallic Fe_(2)M clusters and their subsequent sintering treatment,is developed to engineer novel 3D hierarchical porous structures assembled with MFe_(2)O_(4)(M=Co,Mn,Ni and Zn)nanoparticles confined within carbon outer shell(denoted as MFe_(2)O_(4)@C HPSs).In this intriguing construction,it can be observed that MFe_(2)O_(4)@C HPSs comprised of carbon coated secondary MFe_(2)O_(4)nanoparticles with an interconnected carbon network.The as-prepared MFe_(2)O_(4)@C HPSs possess combined advantages of high capacity of MFe_(2)O_(4)and high conductivity of carbon.As expected,the MFe_(2)O_(4)@C HPSs offer a high reversible capacity,high cycling stability and superior rate performance.The interconnected conductive carbon shells facilitates fast ion and electron transport and accommodates the mechanical strain.In addition,nanosized MFe_(2)O_(4)particles,which shorten the ion-transport path and provide extra electroactive sites,also improve the reaction kinetics.Moreover,these MFe_(2)O_(4)@C HPSs exhibit good structural integrity during repeated charging and discharging.The research perspective and strategy reported here are highly versatile and shed new light on the synthesis of other advanced electrode for various applications.

Hot spots engineering by dielectric support for enhanced photocatalytic redox reactions

Regulating the surface plasmon resonance(SPR)of metallic nanostructures is of great interests for optical and catalytic applications,however,it is still a great challenge for tuning SPR features of small metallic nanoparticles(<10 nm).In this work,we design a unique dielectric support-urchin-like mesoporous silica nanoparticles(U-SiO_(2))with ordered long spikes on its surface,which can well enhance the SPR properties of~3 nm gold nanocrystals(AuNCs).The U-SiO_(2)not only realizes the uniform self-assembly of AuNCs,but also prevents their aggregation due to the unique confinement effect.The finite-difference time-domain simulations show that the AuNCs on U-SiO_(2)can generate plasmonic hot spots with highly enhanced electromagnetic field.Moreover,the hot electrons can be effectively and rapidly transferred through the interface junction to TiO_(2).Thus,a high visible-light-driven photocatalytic activity can be observed,which is 3.8 times higher than that of smooth photocatalysts.The concept of dielectric supports engineering provides a new strategy for tuning SPR of small metallic nanocrystals towards the development of advanced plasmon-based applications.

Nanoreactors derived from silica-protection-assisted metal-organic framework

The construction of highly stable and regular nanoreactors is a major challenge.In this work,we use a facile template protection method to obtain ZIF-67@SiO2(JS) and to encapsulate metal oxide nanoparticles(Co3O4) into nanoreactors(SiO2).ZIF-67 crystals provide a cobalt species;SiO2 was first used as a protective layer of ZIF-67 and then as a nanoreactor for metastable metal oxide nanoparticles.On this basis,Co3O4@SiO2 with dodecahedron morphology were synthesized by calcining JS at different tempe ratures,followed by a hydrothermal reaction to obtain Co3(OH)4Si2O5.Subsequently,CoSx and CoP-SiO2 were fabricated through sulfuration and phosphorization.The results in this work show that nanoreactors derived from metal-organic frameworks(MOFs) with a rational structure have broad development prospects.