Dendritic Fibrous Nanosilica Research Articles

Tunable synthesis of dendritic fibrous nano silica using 1-pentanol-water microemulsion at low oil to water ratio

Dendritic fibrous nanosilica (DFNS) is a suitable nano-carrier for loading pesticides with radially oriented pores and a large surface area. The microemulsion method is standard method to prepare DFNS, and 1-pentanol is taken to replace cyclohexane as an oil solvent due to its high stability and nontoxic property. The results showed that the volume ratio of 1-pentanol (oil) to water (O/W) and the molar ratio of hexadecyltrimethylammonium bromide (CTAB) to tetraethylorthosilicate (TEOS) had effected on morphology and adsorption properties of DFNS in the water-CTAB-1-pentanol-ethanol-trimethylbenzene (TMB) microemulsion system. DFNS with bicontinuous concentric lamellar morphologies can be synthesized in this microemulsion at the meager O/W volume ratio (0.025–0.045). It features a tight mesoporous structure with a thin dendritic fibrous in 0.03 to 0.04 O/W volume ratio. The particle sizes, surface areas, and porosity of DFNS were positively correlated with the addition of the silica precursor TEOS. The size of DFNS increased from 123 to about 220 nm with the CTAB/TEOS molar ratio decreasing from 0.119 to 0.050. When the molar ratio of CTAB to TEOS = 0.119, DFNS has a smaller particle size (123 nm) with a larger surface area and abundant honeycomb mesopores; the low O/W volume ratio strategy provides theoretical support for the industrialization development of DFNS and nano-pesticides, which plays a profound role in promoting the sustainable development of pesticide reduction, efficiency and green agriculture.

Cycloaddition of allylic chlorides, aryl alkynes, and carbon dioxide using nanoclusters of polyoxomolybdate buckyball supported by ionic liquid on dendritic fibrous nanosilica

Due to the uncontrolled emissions of CO2 created by industrial procedures that lead to acidification of the oceans and universal warming, various methods have been utilized for direct absorption of CO2 from waste water sources. The generation of green nano catalyst with chemical adjustments to be converted to value-added products can be considered alluring. Therefore, we synthesized Polyoxomolybdate [Mo132] nanoball with different alkyl groups loaded on dendritic fibrous nanosilica by ionic liquid (DFNS/IL/Mo132) using an easy synthetic route. Owing to the DFNS/IL/Mo132 morphology, a suitable external level for CO2 uptake was generated at all Mo132 sites. Results revealed that DFNS/IL/Mo132 positively influenced the preparation efficiency of 3a,4-dihydronaphtho[2,3-c]furan-1(3H)-one through a three-element binding reaction of alkynes, allylic chlorides, and carbon dioxide. This approach is beneficial in terms of profitable efficacy and forbearance of functional groups.

Dendritic Fibrous Nanosilica: Discovery, Synthesis, Formation Mechanism, Catalysis, and CO2 Capture-Conversion.

ConspectusSilica-based mesoporous nanomaterials have been widely used for a range of applications. Although mesopore materials (such as MCM-41 and SBA-15) possess high surface area, due to their tubular pore structures, pore accessibility is restricted, which causes limitations in mass transport. A new nanosilica was needed to overcome these challenges, including better accessibility, controllable particle size, and good stability. In 2010, my group invented dendritic fibrous nanosilica (DFNS), which has now become a family of novel nanosilicas. DFNS has several unique properties: (i) Tunable particle sizes (50 to 1200 nm), (ii) high surface area (500 to 1200 m2/g), (iii) tunable pore volume (0.32 to 2.18 cm3/g), (iv) wide pore size distribution (3.7 to 25 nm) characterized by radially oriented pores, (v) controllable fiber density (number of fibers per sphere), (vi) variable pore size and pore volume, (vi) high thermal (∼800 °C) and hydrothermal stability, and (vii) mechanical stability (∼130 MPa). DFNS possesses unique dendritic fibrous morphology, and hence can be reached from all sides and easily accessible. DFNS can now be synthesized using a open refluxing protocol, which allowed the scale-up of the process with a sustainable E-factor. In the last 12 years, the DFNS family of materials has been extensively studied for their formation mechanism and range of applications such as catalysis, solar energy harvesting, CO2 capture, CO2 conversion, sensing, biomedicine, energy storage and many more.This Account discusses the invention of DFNS, its synthesis with tunable particle size, textural properties (surface area, pore volume, and pore size), and fiber density. In addition, the DFNS formation mechanism via the complex interplay of self-assembly, the dynamics, and coalescence of bicontinuous microemulsion droplets (BMDs) is discussed. Finally, applications of DFNS in a range of fields, that include catalysis, photocatalysis, synthesis of plasmonic black gold, nanosponges of aluminosilicates, CO2 capture, and CO2 conversion to fuel, are presented.

Cycloaddition of propylene oxide and carbon dioxide using CoMn2O4 nanoparticles supported onto dendritic fibrous nanosilica

An environmentally friendly surface modification method was employed to synthesize a solid ionic liquid catalyst appropriate. The fabrication of green heterogeneous nano catalysts by chemical modification is determined to be very attractive in the case of the conversion of CO2 into value-added products. Herein, we reported chemical composition of epoxides, and carbon dioxide to prepare poly(propylene carbonate) in the presence of nanoparticles of CoMn2O4 stably placed on the surface of DFNS (dendritic fibrous nanosilica) by cellulose (cellulose@DFNS-CoMn2O4) as a nanocatalyst. Poly(propylene carbonate) with a Ma (average molecular weight) of 6497 kg/mol and 76% yield was obtained at 2 h and 100 °C as a reaction time and reaction temperature. With the aim of preparing the catalyst, cellulose was used to activate the DFNS surface to be employed as a substrate to support nanoparticles of CoMn2O4. Cellulose eliminates the need for a reducing agent and acts as a reducing natural agent and stabilizing for nanoparticles of CoMn2O4. The morphology of the final compound affected the catalytic feature of ionic liquid catalyst for synthesis of carbonyl compounds.

KCC-1-nPr-NH-Arg as an efficient organo-nanocatalyst for the green synthesis of 1,8-dioxo decahydroacridine derivatives.

In the present work, an innovative biocompatible heterogeneous organo-nanocatalyst is prepared based on the grafting of arginine amino acid on the channels and pores of dendritic fibrous nano silica. The designed organo-nanocatalyst (KCC-1-nPr-NH-Arg) was characterized by using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, map analysis, and adsorption/desorption instruments. The results of analysis show that the engineered catalyst has uniform fibrous spheres and dendritic structure with high surface area (104.9 m2 /g) and great pore volume (0.83 cm3 g-1 ). Because of exceptional dendritic structure of the prepared organo-nanocatalyst, the active sites are available and the difusion and adsorption capacity of the reagents and products increase in the pores and channels of the catalyst. Hence, KCC-1-nPr-NH-Arg was used as an capable heterogeneous basic nanocatalyst in the synthesis of 1,8-dioxo decahydroacridine derivatives from the one-pot four component reactions of aromatic aldehydes, dimedone, and ammonium acetate in solvent free conditions with shorter reaction times (13-35 minutes) and higher yields (94%-98%) in evaluation with other reported works. It is expected that the green organo-nanocatalyst can be used to synthesize other organic compounds.

Utilization of a mixed matrix membrane modified by novel dendritic fibrous nanosilica (KCC-1-NH-CS2) toward water purification.

Various nanostructures have been used to improve the performance of nanocomposite membranes. Dendritic fibrous nanosilica (DNFS) is a new nanostructure and its performance as an adsorbent for the removal of pigments has been investigated. In this study, a type of modified dendritic fibrous nanosilica containing CS2 groups (KCC-1-NH-CS2) was synthesized and inserted as an additive into nanocomposite acrylonitrile–butadiene–styrene (ABS) membranes. Due to its high surface area and unique functional groups, this additive can improve the membrane's ability to remove dyes from aqueous media. Synthesized nanostructures and membranes were characterized by different analysis. The results showed that the water contact angle as a measure of surface hydrophilicity in membrane M5 compared to membrane M1 decreased from 79° to 67°. Water absorption (swelling degree) in membrane M5 increased by more than 100% compared to the bare membrane. Also, this membrane, despite having high porosity (42%) and improved flux (35 L m−2 h−1), has a better efficiency in removing dyes (MG: 99%, MB: 98%, MO: 82%) in comparison with other reported works.

Fabrication of hollow fibrous nanosilica with large pore channels.

The fabrication of hollow mesoporous nanosilica with well-defined structural features for optimizing the integration of functional components is a challenge. Herein, we report a facile preparation of hollow fibrous nanosilica (HFNS) with high specific surface area (666 m2 g-1), fiber-like mesoporous architectures in the inner and outer shells, and large pore channels (16.22 nm) via selective self-etching of dendritic fibrous nanosilica in an aqueous medium. The specific surface area and pore diameter increased significantly after the formation of a cavity in the center, resulting in HFNS. The HFNS can serve as a robust support for the controllable growth of gold nanoparticles with maximum catalytic performance for 4-nitrophenol reduction.

Correction: Determination of aflatoxin M1 using an aptamer-based biosensor immobilized on the surface of dendritic fibrous nano-silica functionalized by amine groups

Correction for ‘Determination of aflatoxin M1 using an aptamer-based biosensor immobilized on the surface of dendritic fibrous nano-silica functionalized by amine groups’ by Houman Kholafazad kordasht et al., Anal. Methods, 2019, 11, 3910–3919, DOI: 10.1039/C9AY01185D.

G-C3N4/dendritic fibrous nanosilica doped with potassium for photocatalytic CO2 reduction

The preferential reduction of CO2 over water to generate methane by potassium ion doping into the matrix of g-C3N4/DFNS.

Adenine Functionalized Dendritic Fibrous Nanosilica as Bifunctional Catalyst for Co2 Fixation into Cyclic Carbonate

Adenine Functionalized Dendritic Fibrous Nanosilica as Bifunctional Catalyst for Co2 Fixation into Cyclic Carbonate

A review on recent advances in dry reforming of methane over Ni- and Co-based nanocatalysts

The recent environmental-related issues such as climate change and global warming have sparked scientists' interest in finding a way to reduce the emission of greenhouse gases through dry reforming of CH4. As a result of this reaction, not only H2 is produced, but also CO2 and CH4 are reduced. Catalysts are needed due to the enhancement of the kinetics of the reaction. Non-noble metals like Ni, Co, etc., have shown promising activity, they are readily available, and have low cost; consequently, they have been widely employed for the reaction. In this paper, the recent advances in the development of the Ni- and Co-based nanocatalysts for DRM reaction, including the use of different supports and promoters, the addition of alkaline earth metals, and new structures like mesoporous silica and dendritic fibrous nano silica as supports were reviewed.

Sn4+-doped dendritic fibrous nanosilica (DFNS) nanoparticles as photocatalyst for degradation of rhodamine B

Sn4+-doped dendritic fibrous nanosilica (DFNS) nanoparticles as photocatalyst for degradation of rhodamine B

Metformin functionalized dendritic fibrous nanosilica (KCC-1-nPr-Met) as an innovative and green nanocatalyst for the efficient synthesis of tetrahydro-4H-chromene derivatives.

An innovative nanocatalyst (KCC-1-nPr-Met) has been prepared from the covalent attachment of metformin on the channels and the pores of n-propyl amine functionalized dendritic fibrous nanosilica (DFNS) and used towards efficient, green, and high yield synthesis of tetrahydro-4H-chromenes derivatives by one-pot three-component reaction of aromatic aldehydes, malononitrile, and dimedone in H2 O-EtOH at room temperature. The designed nanocatalyst has been characterized by energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), and adsorption/desorption analysis (BET) techniques. Also, field emission scanning electron microscopy (FE-SEM) was used to study the morphology of prepared nanocatalyst. The engineered nanocatalyst with uniform fibrous spheres has dendritic structure, high pore volume (0.35 cm3 /g), and great surface area (178 m2 /g). Hence, the specific dendritic structure of the prepared nanocatalyst not only improve the diffusion ability of the reactants and products, but also, increase the availability of dynamic sites in the pores and channels of the catalyst. According to the obtained results, a unique strategy was proposed towards the synthesis of important biologically active scaffolds in the presence of nontoxic and environmental friendly nanocatalyst and media. Milder reaction conditions (room temperature), shorter reaction times (5-30 minutes), excellent yields (92%-98%) of the products with higher purity, very simple workup procedure, and using of EtOH: H2 O as a green solvent are the advantages of the presented work.

Efficient transformation of 5-hydroxymethylfurfural to ethyl levulinate over the Brønsted acidic ionic liquid functionalized dendritic fibrous nanosilica spheres

Brønsted acidic ionic liquid (BAIL) functionalized dendritic fibrous nanosilica sphere catalysts, [C 3 PrIm][SO 3 CF 3 ]-DFNS (C 3 = PrSO 3 H), are prepared via a hexadecylpyridinium bromide reverse micelle-directed co-condensation of tetraethoxysilane and 3-chloropropyltriethoxysilane in a water-in-oil emulsion system followed by successive chemical modification with imidazole, 1,3-propanesultone and trifluoromethane sulfonic acid, and the particle diameter, fiber thickness and fiber density of the catalysts are well-adjusted by changing the composition of the starting materials. The [C 3 PrIm][SO 3 CF 3 ]-DFNS catalysts are successfully applied in transformation of 5-hydroxymethylfurfural (HMF) to ethyl levulinate (EL). Combination of superstrong Brønsted acidity and unique open three-dimensional dendritic fibrous nanostructures, the [C 3 PrIm][SO 3 CF 3 ]-DFNS can transform HMF in ethanol media rapidly and completely; nevertheless, the selectivity to EL remarkably depends on the fiber thickness and fiber density, which affect diffusion and mass transfer of the reactants and products as well as the accessibility to the acid sites. Among the tested [C 3 PrIm][SO 3 CF 3 ]-DFNS catalysts, the [C 3 PrIm][SO 3 CF 3 ]-DFNS- 1 with the thinnest fiber sheet and considerably high fiber density exhibits the highest selectivity to EL (93.0%). The [C 3 PrIm][SO 3 CF 3 ]-DFNS catalysts also show good reusability, and they can be reused at least for five times without obvious changes of the reactivity, total selectivity, morphology, textural properties and chemical structure. • The [C 3 PrIm][SO 3 CF 3 ]-DFNS are prepared by CPB reverse micelle-directed co-condensation route. • Particle diameter, fiber thickness and fiber density of the catalysts can be well-regulated. • The catalysts with thin fiber thickness and high fiber density exhibit high ethanolysis activity. • The [C 3 PrIm][SO 3 CF 3 ]-DFNS exhibit excellent reusability and stability in the target reaction.

Design and structure of nitrogen and oxygen co-doped carbon spheres with wrinkled nanocages as active material for supercapacitor application

Nitrogen/oxygen co-doped carbon spheres with wrinkled nanocages (NOCN) were successfully synthesized using dendritic fibrous nanosilica (DFNS) as sacrificial solid template, glucose as a carbon source, and melamine as the nitrogen source. The obtained carbon nanocages (NOCN-850-3) exhibit human brain-like winkle shape, high specific surface area (813 m2 g−1), high nitrogen (16.24 at%) and oxygen contents (5.36 at%). In addition, the obtained carbon presents good specific capacitance of 311.1 F g−1 at a current density of 0.5 A g−1 in 6 M KOH and remarkable rate performance (118.1 F g−1 at a current density of 30 A g−1) and cycle stability (97.6% retention after 10,000 charge–discharge performance cycles at 10 A g−1). Meanwhile, the NOCN-850-3-based coin-type symmetric supercapacitor exhibits a maximum energy density of 12. 3 W h kg−1 at a power density of 175 W kg−1 and also a relatively low resistance in 6 M KOH aqueous electrolyte. Thus, the unique structure and nitrogen/oxygen co-doping characteristic endue the electrode material a potential application in supercapacitors.

CQDs-MoS2 QDs loaded on Dendritic fibrous Nanosilica/Hydrophobic waterborne polyurethane acrylate for antibacterial coatings

Since bacterial infections are the cause of many diseases, death, and disability, considerable attention has been paid to the preparation of antibacterial surfaces. Anti-adhesive and bactericidal synergistic surfaces show promising antimicrobial applications due to the removal and killing effect of microorganisms. Herein, we proposed a leather coating surface with hydrophobic and photocatalytic antibacterial properties. Dendritic fibrous nanosilica (DFNS) loaded with carbon quantum dots (CQDs) and MoS2 QDs (DFNS@CQDs-MoS2) nanoparticles were successfully prepared, which exhibited excellent photocatalytic antibacterial activity. Specifically, the DFNS@CQDs-MoS2 nanoparticles exhibited antibacterial activities of 99.98%, 95.35%, and 99.99% against Escherichia coli, Staphylococcus aureus, and Aspergillus niger, respectively. Then, hydrophobic waterborne polyurethane acrylate (HWPUA) was developed, which exhibited enhanced bacterial adhesion resistance. Furthermore, the HWPUA/DFNS@CQDs-MoS2 coating completely inactivated the residual bacterial cells. Therefore, the synergistic antibacterial coatings developed in this work could have potential applications as antibacterial surfaces.

Poly(amidoamine) dendrimer decorated dendritic fibrous nano-silica for efficient removal of uranium (VI)

Efficient adsorbents for U(VI) removal from aqueous solution is particularly important for energy strategy and environmental safety. Although dendritic fibrous nano-silica (DFNS) with large surface area, good stability and porous structure is attractive, modification of DFNS is an effective strategy to realize the efficient removal of U(VI). Hyper-branched poly(amidoamine)(PAMAM) with abundant amine/amide groups shows great potential in U(VI) adsorption. Herein, PAMAM was grown onto the rigid DFNS to obtain the nanocomposite. The nanocomposite served as a novel adsorbent for U(VI) removal and exhibited fast adsorption kinetics of less than 180 ​min and considerable adsorption capacity of 215.52 ​mg ​g-1 owing to the open gully-like structure and functional groups on the surface of the absorbent. The adsorption mechanism was discovered to be complexation between amine/amide groups and U(VI) ions by EDS and XPS analysis. Furthermore, the adsorbent showed an excellent reusability.

Unravelling the structural hierarchy in microemulsion droplet templated dendritic fibrous nano silica

Microemulsion-templated dendritic fibrous nanosilica (DFNS) has attracted considerable attention owing to their unique accessible pore structure and high-surface-area but their complex structural hierarchy is still intriguing. In this work, a correlative quantification of the hierarchical structure of such nanospheres has been presented based upon three complementary techniques; small-angle scattering, gas sorption, and electron microscopy. Analysis of scattering data over a wide range of wave-vector transfer using polydisperse Teubner Strey model reveals three distinct levels of correlated bicontinuous morphology and the pore-size distribution from N2 gas sorption resembles well with the results obtained from scattering analysis. The formation mechanism of such hierarchical pore morphology in these nanospheres is elucidated and it is observed that a relative variation in periodicity, sheet thickness, and their correlation significantly affects the specific surface area and pore structure, which is strongly influenced by hydrolysis rate and reaction time.

Origin of the Hierarchical Structure of Dendritic Fibrous Nanosilica: A Small-Angle X-ray Scattering Perspective.

The discovery of dendritic fibrous nanosilica (DFNS) has attracted great attention to the field of catalysis, CO2 capture, drug delivery due to its distinct morphology, and pore size distribution. Despite extensive research, the understanding of the DFNS formation process and its internal structure remains incomplete as microscopy and gas sorption techniques were not able to provide necessary in-depth structural information due to their inherent limitations. In the current work, we present a structural model of DFNS derived using small-angle X-ray scattering (SAXS) supported by 129Xe nuclear magnetic resonance (NMR), which provided intricate details of DFNS and its internal structure. Mechanistic understanding of the DFNS formation and growth process was achieved by performing time-resolved SAXS measurements during the synthesis of DFNS, which unveils the evolution of two levels of a bicontinuous microemulsion structure responsible for intricate DFNS morphology. The validity and the accuracy of the SAXS method and the model were successfully established through a direct correlation among the functionality of the DFNS scattering profile and its pore size distribution, as well as results obtained from the 129Xe NMR studies. It has been established that the DFNS structure originates from direct modulation of the bicontinuous structure controlled by a surfactant, a co-surfactant, and the silicate species formed during hydrolysis and the condensation reaction of the silica precursor.

Overcoming the limitations of anthracene alkylation using SZ-DeAl-DFNS acid catalyst

In situ formation of composite micro-mesoporous dendritic fibrous nano-silica (DFNS) and Al-DFNS was prepared using a cetylpyridinium bromide (CPB) template synthetic system. Dealumination is induced by impregnation of zirconium with flux followed by a sulfuric acid treatment. This procedure results in a series of highly uniform nano-spheres, which exhibit stronger acid property than that of Al-MCM-41. In the selective alkylation of anthracene with tert‑amyl alcohol, SO42− modified Zr-contained dealuminated Al-DFNS (SZ-DeAl-DFNS) shows great catalytic activity and higher conversion (60.8%). The DFNS samples were characterized with XRD, SEM, TEM, NH3-TPD and other techniques. The results reveal that DFNSs consist of center-radial micro-mesopores and that the acid contribution of SZ-DeAl-DFNS is much broader, as compared with amorphous aluminosilicate