In situ synthesis of silver nanostructures on magnetic Fe₃O₄@organosilicon microparticles for rapid hydrogenation catalysis

Abstract

Novel protocol to prepare multifunctional magnetic organic-inorganic nanostructured catalyst of Fe 3 O 4 @organosilicon/Ag with tailored properties is developed. Such nanostructure design endows the catalyst with superparamagnetism (11.6 emu g -1 ), excellent oxidation resistance, and catalytic activity. Fe 3 O 4 nanoparticles (NPs) are encapsulated with porous organosilicon via improved self-assembly of flexible-bridged organosilicon precursor without templates. Subsequently, dispersed Ag NPs are in situ grown on the porous microparticles via silver mirror reaction. The as-prepared multifunctional catalysts are characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, vibration sample magnetometer, X-ray diffraction, thermal gravimetric analysis, and nitrogen adsorption and desorption, respectively. The resultant hybrid microparticles possess microand nano-pores, and exhibit a small hysteresis loop and low coercivity.Meaningfully, they exhibit exceptional catalytic performance for the reduction of 4-nitrophenol in the presence of sodium borohydride and could be reused at least 9 times with excellent stability by means of convenient magnetic separation. The catalyst could be employed to reduce other dyes such as methylene blue, orange G and rhodamine B, and their corresponding reductions follow pseudo-first-order reaction. Therefore, the proposed structure design and scalable route for the synthesis of hierarchical catalyst can pave the way for synthesizing other catalyst systems to address the diverse reaction demands.

Amorphizing of Ag Nanoparticles under Bioinspired One‐step Assembly of Fe3O4‐Ag/rGO Hybrids via Self‐redox Process with Enhanced Activity

“…. Similar work has also been reported in our previous work . Unfortunately, they tend to aggregate due to their high surface energy, leading to the drops of catalytic performance.…”

“…For the two peaks at the L 2 edge (719–725 eV), the left peak is pretty stronger than the right one, agreeing well with the reported Fe 3 O 4 NPs. The absence of obvious shakeup satellite structures at the higher binding energy side of both main peaks (about 718.8 and 729.5 eV), demonstrates no generation of Fe 2 O 3 phase . The relative areas ratio of the deconvoluted peak assigned to Fe 2+ and Fe 3+ are calculated to be c.a.…”

“…Figure shows the N 2 adsorption–desorption isotherms and Barrett–Joyner–Halenda (BJH) pore size distribution of Fe 3 O 4 /rGO, Fe 3 O 4 ‐Ag/rGO‐1 and Fe 3 O 4 ‐Ag/rGO‐2, respectively. Each isotherm can be classified to a type‐IV isotherm with a small hysteresis loop, indicating the existence of mesopores . The BET surface area, pore volume and average pore size are summarized in Table S2.…”

“…For example, layer‐by‐layer assembly requires the synthesis of Fe 3 O 4 NPs at high temperature, the modification of Fe 3 O 4 NPs, and the reduction of Ag + ions . Second, compared with the introduction of AgNPs in previous works, no hazardous and toxic reagents, such as sodium borohydride and hydrazine hydrate, are employed. Third, the coprecipitation process enables the Fe 3 O 4 to play a crucial role in transferring the crystalline AgNPs into the amorphous ones, which affords higher concentration of active sites .…”

Applications of Nanomaterials Based on Magnetite and Mesoporous Silica on the Selective Detection of Zinc Ion in Live Cell Imaging

“…On the other hand, all of the isotherms of magnetite nanoparticles could be classified as a type III isotherm with H3 hysteresis loop, according to the IUPAC and Brunauer-Deming-Deming-Teller (BDDT) classification [ 53 , 54 ]. The N 2 adsorption/desorption isotherms of Fe 3 O 4 -H and Fe 3 O 4 -C ( Figure 4 ) exhibited the characteristic type III isotherm with a sharp increase in adsorption at P/P 0 = 0.8–1, because of the capillary condensation of the nitrogen in the structure.…”