Progress toward Room-Temperature Synthesis and Functionalization of Iron-Oxide Nanoparticles

• Published in: International journal of molecular sciences 2022-07, Vol.23 (15), p.8279
• Main Authors: Flores-Cano, Diego A, Checca-Huaman, Noemi-Raquel, Castro-Merino, Isabel-Liz, Pinotti, Camila N, Passamani, Edson C, Litterst, Fred Jochen, Ramos-Guivar, Juan A
• Format: Article
• Language: English
• Subjects: Cooling curves; Electron energy; Electron energy loss spectroscopy; Ferric oxide; functionalization; Goethite; Iron - chemistry; Iron 57; iron oxide; Iron oxides; Lasers; Magnetic saturation; Magnetite; Mossbauer spectroscopy; Nanomaterials; Nanoparticles; Nanoparticles - chemistry; Organic chemistry; Oxalic acid; Oxides - chemistry; Particle Size; Phase transitions; Polystyrene resins; Raman spectroscopy; Room temperature; room-temperature synthesis; Sodium polystyrene sulfonate; Temperature; Thin walled shells; X-ray diffraction
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms23158279

Novel magnetic nanohybrids composed of nanomaghemite covered by organic molecules were successfully synthesized at room temperature with different functionalization agents (sodium polystyrene sulfonate, oxalic acid, and cetyltrimethylammonium bromide) in low and high concentrations. Structural, vibrational, morphological, electron energy-loss spectroscopy, magnetic, and Mössbauer characterizations unraveled the presence of mainly cubic inverse spinel maghemite (γ-Fe O ), whilst X-ray diffraction and Fe Mössbauer spectroscopy showed that most samples contain a minor amount of goethite phase (α-FeOOH). Raman analysis at different laser power revealed a threshold value of 0.83 mW for all samples, for which the γ-Fe O to α-Fe O phase transition was observed. Imaging microscopy revealed controlled-size morphologies of nanoparticles, with sizes in the range from 8 to 12 nm. Organic functionalization of the magnetic nanoparticles was demonstrated by vibrational and thermogravimetric measurements. For some samples, Raman, magnetic, and Mössbauer measurements suggested an even more complex core-shell-like configuration, with a thin shell containing magnetite (Fe O ) covering the γ-Fe O surface, thus causing an increase in the saturation magnetization of approximately 11% against nanomaghemite. Field cooling hysteresis curves at 5 K did not evidence an exchange bias effect, confirming that the goethite phase is not directly interacting magnetically with the functionalized maghemite nanoparticles. These magnetic nanohybrids may be suitable for applications in effluent remediation and biomedicine.