Gold nanoparticle modified magnetic fibrous silica microspheres as a highly efficient and recyclable catalyst for the reduction of 4-nitrophenol

Abstract

Recently, catalysts with easily accessible active sites and high efficiency and recyclability have triggered various research interests. In this study, we prepared uniform fibrous silica microspheres with a γ-Fe2O3 magnetic core (γ-Fe2O3@SiO2@KCC-1) as the catalyst support. The distance between two fibers was approximately 10-20 nm. Au nanoparticles (NPs) were highly dispersed on the silica fibers without aggregation to form the nanocatalyst Au/γ-Fe2O3@SiO2@KCC-1. The catalytic activity of Au/γ-Fe2O3@SiO2@KCC-1 for the reduction of 4-nitrophenol (4-NP) with NaBH4 was measured by UV-vis spectroscopy. Au/γ-Fe2O3@SiO2@KCC-1 exhibited better catalytic activity toward the reduction of 4-NP compared with other reported Au NPs-based catalysts. The high catalytic activity was mainly attributed to the easy accessibility of the Au NPs of the prepared nanocatalyst. In addition, Au/γ-Fe2O3@SiO2@KCC-1 could be easily recycled by applying an external magnetic field while maintaining the catalytic activity without significant decrease even after six runs. The unique properties provided an ideal platform to study various noble metal/γ-Fe2O3@SiO2@KCC-1 nanocatalysts that can be potentially applied in a wide variety of fields such as catalysis and green chemistry.

Size and Fiber Density Controlled Synthesis of Fibrous Nanosilica Spheres (KCC-1)

“…The other textual properties also changed significantly. The pore volume for KCC-1 (730) was 1.95 cm 3 /g, while for KCC-1 (370), it was 2.18 cm 3 /g, the highest reported to date for such materials 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 . Its surface area was also very high (1244 m 2 /g), double the previously reported surface area value for KCC-1 17–55 .…”

“…After our discovery of KCC-1 in march 2010, several reputed groups worldwide reported the successful use of KCC-1 for various applications such as catalysis, photocatalysis, CO 2 capture-conversion, sensing, detection and extraction of ions, supercapacitors, drug delivery and other biomedical applications 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 . Although KCC-1 nano-spheres possess unique textural and physical properties and show a dramatic enhancement in activity, control over their particle size, fiber density and textural properties (surface area, pore volume, pore size) has not been achieved yet 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 , despite their being critical parameters for the successful development of KCC-1-supported catalysts/photocatalysts and sorbents as well as in drug delivery. For example, drug delivery applications need smaller particles (smaller than 200 nm) 16 , while catalysts will be more stable if the particle size is larger (without comp...…”

Improving the size uniformity of dendritic fibrous nano-silica by a facile one-pot rotating hydrothermal approach

“…Diverse guest species, such as functional molecules or nano-particles (NPs), could be easily transported through the radial porous architectures to achieve their efficient loading or react with the chemically active sites on these nanochannels. [20][21][22][23][24][25][26][27][28] During the last nine years, KCC-1 has attracted considerable attention and experienced rapid development in terms of synthesis techniques, formation mechanisms, functionalization approaches, and application elds. 5,29 Even though great progress has been achieved, there still exist many issues surrounding the synthesis and application of KCC-1.…”

Synthesis of Cu2O@Ag Polyhedral Core–Shell Nanoparticles by a Thermal Decomposition Approach for Catalytic Applications

“…The end product 4‐aminophenol is used in various applications 29. An aqueous solution of 4‐nitrophenol shows a UV/Vis absorbance band at λ = 317 nm, and the absorbance maximum is redshifted to λ = 400 nm upon the addition of freshly prepared NaBH 4 owing to the formation of the 4‐nitrophenolate ion 29,30. In the present study, the reduction of 4‐nitro‐ to 4‐aminophenol was performed with different Cu 2 O@Ag polyhedral core–shell nanoparticles (C1A to C4A), pure Cu 2 O microcrystals (C1 to C4), silver nanoparticles, a physical mixture of Cu 2 O octahedra with silver nanoparticles (Ag = 5.1 wt.‐%), and PVP‐stabilized silver nanoparticles.…”