- 标题
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Direct synthesis of ultrasmall and stable magnetite nanoparticles coated with one single carbon layer for sensitive surface-enhanced Raman scattering
摘要： Ultrasmall spherical magnetite nanoparticles (Fe3O4 NPs) coated with one single carbon layer (Fe3O4@1C NPs) were directly synthesized by a simple, fast one-step hydrothermal reaction at low temperature (200℃). The as-synthesized Fe3O4@1C NPs were easily separated and purified from the resultant mixture, without the need for any additional energy input and chemicals. The as-purified Fe3O4@1C NPs not only displayed typical superparamagnetic behavior but also exhibited quite good long-term stability after being exposed to the open air under the room conditions for more than 2 months. Importantly, the long-term stored Fe3O4@1C NPs exhibited a highly sensitive surface-enhanced Raman spectroscopy (SERS) response toward Rhodamine-b (RdB) molecules with low concentration. The multifunctional and recyclable Fe3O4@1C NPs presented a prospective application for the selective enrichment and sensitive SERS detection of chemical and biomolecular assays.
关键词： coated with one single carbon layer (Fe3O4@1C NPs),Dehydration reaction,Saturation magnetization,Long-term stability,Magnetite nanoparticles (Fe3O4 NPs)
更新于2025-11-14 17:03:37
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Enhancing saturation magnetization of Mg ferrite nanoparticles for better magnetic recoverable photocatalyst
摘要： Simple combustion route was implemented for the preparation of Mo-substituted magnesium ferrite nanoparticles; MgFe2?2xMoxO4 (x = 0.0, 0.1, 0.2 and 0.3). Samples, with x = 0.0, 0.1 and 0.2, revealed only the cubic spinel ferrite phase. Sample with x = 0.3 showed very small amount of FeMoO4, beside MgFe2O4. The lattice parameter diminished with increasing molybdenum contents to x = 0.1, then increased at x ≥ 0.2. The saturation magnetization (Ms) increased from 15.65 to 32.05 emu/g with low level of Mo6+ substitution (x = 0.1), then declined with x > 0.1. This is the first investigation to report Ms of Mg ferrite nanoparticles higher than its bulk value. The change in magnetic properties is correlated with cation distribution between tetrahedral sites (A) and octahedral sites (B). Mo6+ replaced the Fe3+ position in the tetrahedral A-sites for x = 0.1. In samples with x ≥ 0.2, Mo6+ occupied both A-sites and B-sites. Mo substitution decreased the crystallite size and increased the microstrain. Mo substitution in MgFe2O4 enhanced the photocatalytic action compared to bare MgFe2O4. The enhancement was due to the increase in structure defect that inhibits the electrons–holes recombination as well as the increase in surface area.
关键词： photocatalytic activity,Mg ferrite nanoparticles,Mo substitution,saturation magnetization
更新于2025-09-09 09:28:46