Fibrous Silica Nanospheres Research Articles

Synthesis of manganese incorporated hierarchical mesoporous silica nanosphere with fibrous morphology by facile one-pot approach for efficient catalytic ozonation

Manganese incorporated fibrous silica nanosphere (MnOx-0.013/KCC-1) was synthesized by one step hydrothermal method for the first time and its catalytic activity for ozonation of oxalic acid was studied. For comparison, manganese loaded MCM-41 (MnOx-0.013/MCM-41) was prepared by impregnation method. Various characterizations showed that the morphological, structural and textural properties of MnOx-0.013/KCC-1 were well preserved. Ozonation and catalytic ozonation by MnOx-0.013/KCC-1 and MnOx-0.013/MCM-41 led to 4, 85 and 60% reduction in TOC respectively. Furthermore, 0.05 and 1.2mgL−1 leaching of Mn was detected from MnOx-0.013/KCC-1 and MnOx-0.013/MCM-41, which are approximately 2.0 and 42.0% of the total Mn present in MnOx-0.013/KCC-1 and MnOx-0.013/MCM-41 respectively. The high catalytic activity was attributed to the generation of hydroxyl radical. Surface hydroxyl groups investigated by using phosphates and ATR-FTIR were believed to be the active sites. Our proposed method of synthesis can be generalized for the synthesis of other metal oxides incorporated fibrous silica for environmental catalysis and other catalytic reactions.

Gold Nanoparticles Supported on Fibrous Silica Nanospheres (KCC‐1) as Efficient Heterogeneous Catalysts for CO Oxidation

AbstractGold nanoparticles (Au NPs) of different sizes were supported on fibrous silica nanospheres (KCC‐1) by various methods. The size and the location of the Au NPs on the support were found to depend on the preparation method. The KCC‐1‐supported Au NPs were thoroughly characterized by using HR‐TEM, XRD, X‐ray photoelectron spectroscopy, UV, and Brunauer–Emmett–Teller surface area measurements and were applied in catalysis for the oxidation of CO. The catalytic performance is discussed in relation to the morphological properties of KCC‐1.

Preparation of a novel KCC-1/nylon 6 nanocomposite via electrospinning technique

In this research, a novel nanofibrous composite of KCC-1/nylon 6 was prepared using electrospinning techniques. First, fibrous silica nanospheres (KCC-1) were synthesized via conventional polycondensation method with a new solvent system. The scanning electron microscopy (SEM) images showed a spongy spherical morphology with a uniform distribution of particle sizes and an average diameter of around 305 nm. Synthesized KCC-1 nanospheres are considered as mesoporous materials due to their high BET specific surface area of 576 m2 g−1 and BJH average pore diameter of 3.28 nm. The KCC-1/nylon 6 composite was fabricated by preparing a dispersion of nanosilica (10–50 % w/w) in a solution of nylon 6 (15 % w/v) in formic acid. Upon applying a high voltage, the nonwoven electrospun KCC-1/nylon 6 composite nanofibers were obtained. The KCC-1 nanospheres were arranged in line along the nylon 6 fibers like rosary beads wrapped in the polymer. Based on the SEM images, we obtained a well-distributed nanocomposite even at higher silica content. The prepared KCC-1/nylon 6 composite showed 29–55 % higher BET specific surface area compared with pure nylon 6 nanofibers which makes it a good candidate to be used as a sorbent material for environmental or drug delivery applications.

Palladium Nanoparticles Supported on Fibrous‐Structured Silica Nanospheres (KCC‐1): An Efficient and Selective Catalyst for the Transfer Hydrogenation of Alkenes

AbstractAn efficient palladium catalyst supported on fibrous silica nanospheres (KCC‐1) has been developed for the hydrogenation of alkenes and α,β‐unsaturated carbonyl compounds, providing excellent yields of the corresponding products with remarkable chemoselectivity. Comparison (high‐resolution TEM, chemisorption) with analogous mesoporous (MCM‐41, SBA‐15) silica‐supported Pd nanocatalysts prepared under identical conditions, demonstrates the advantage of employing the fibrous KCC‐1 morphology versus traditional supports because it ensures superior accessibility of the catalytically active cores along with excellent Pd dispersion at high metal loading. This morphology ultimately leads to higher catalytic activity for the KCC‐1‐supported nanoparticles. The protocol developed for hydrogenation is advantageous and environmentally benign owing to the use of HCOOH as a source of hydrogen, water as a solvent, and because of efficient catalyst recyclability and durability. The recycled catalyst has been analyzed by XPS spectroscopy and TEM showing only minor changes in the oxidation state of Pd and in the morphology after the reaction, thus confirming the robustness of the catalyst.

Ni@Pd core–shell nanoparticles modified fibrous silica nanospheres as highly efficient and recoverable catalyst for reduction of 4-nitrophenol and hydrodechlorination of 4-chlorophenol

In this study, a novel fibrous nano-silica (KCC-1) based nanocatalyst (Ni@Pd/KCC-1) was synthesized by modifying KCC-1 using Ni@Pd core–shell nanoparticles (NPs). The Ni@Pd/KCC-1 was used in the catalytic reduction of 4-nitrophenol (4-NP) and hydrodechlorination (HDC) of 4-chlorophenol (4-CP). KCC-1, prepared by hydrothermal method, exhibited a dandelion-like shape, high surface area, and easy accessibility of active sites. The Ni@Pd NPs possessed a magnetic nickel (Ni) core with palladium (Pd) shell structural composite. Thus, use of Ni led to the reduced consumption of Pd without sacrificing the overall catalytic performance, simultaneously making it reusable as it could be conveniently recovered from the reaction mixture by using an external magnetic field. Immobilization of the Ni@Pd NPs on KCC-1 nanospheres not only prevented their aggregation, but also significantly enhanced the accessibility of the catalytic active sites. The Ni@Pd/KCC-1 nanocatalyst displayed excellent catalytic activities for both the reduction of 4-NP and the HDC of 4-CP under green conditions. The above-mentioned approach based on fibrous KCC-1 and Ni@Pd NPs provided a useful platform for the fabrication of noble metal-based cost-effective nanocatalyst with easy accessibility, and acted as a promising candidate for numerous catalytic applications.

ChemInform Abstract: Synthesis of Fibrous Nano‐Silica‐Supported TEMPO and Its Application in Selective Oxidation of Alcohols.

AbstractTEMPO supported on fibrous silica nanospheres is shown to be an efficient catalyst for the selective oxidation of (hetero)aromatic, aliphatic, allylic, and secondary alcohols.