Iron Oxide Nanoparticles: A Review on the Province of Its Compounds, Properties and Biological Applications

Materials science and technology, with the advent of nanotechnology, has brought about innumerable nanomaterials and multi-functional materials, with intriguing yet profound properties, into the scientific realm. Even a minor functionalization of a nanomaterial brings about vast changes in its properties that could be potentially utilized in various applications, particularly for biological applications, as one of the primary needs at present is for point-of-care devices that can provide swifter, accurate, reliable, and reproducible results for the detection of various physiological conditions, or as elements that could increase the resolution of current bio-imaging procedures. In this regard, iron oxide nanoparticles, a major class of metal oxide nanoparticles, have been sweepingly synthesized, characterized, and studied for their essential properties; there are 14 polymorphs that have been reported so far in the literature. With such a background, this review's primary focus is the discussion of the different synthesis methods along with their structural, optical, magnetic, rheological and phase transformation properties. Subsequently, the review has been extrapolated to summarize the effective use of these nanoparticles as contrast agents in bio-imaging, therapeutic agents making use of its immune-toxicity and subsequent usage in hyperthermia for the treatment of cancer, electron transfer agents in copious electrochemical based enzymatic or non-enzymatic biosensors and bactericidal coatings over biomaterials to reduce the biofilm formation significantly.

Hematite nanoparticles decorated nitrogen-doped reduced graphene oxide/graphitic carbon nitride multifunctional heterostructure photocatalyst towards environmental applications

The carcinogenic heavy metals and aromatic organic compounds linger as wastewater pollutants implying great menace to the ecological balance. To solve these environmental pollution problems, the photocatalytic process is an...

Effect of heat treatment on the photocatalytic activity of α-Fe2O3 nanoparticles: towards diclofenac elimination

α-Fe₂O₃ nanoparticles were synthesized via a straightforward method. XRD, FTIR, SEM, ESR, and DRS techniques investigated the influence of various calcination temperatures on the crystal structure, optical, and photocatalytic properties of the samples. The obtained results demonstrated that the average crystallite size increased with the increase in the calcination temperature. Measured and computed optical properties were in accordance and the bandgap energy decreased with the increase in the calcination temperature. The highest photocatalytic degradation efficiency for diclofenac (DCF) was obtained with the sample calcinated at 300 °C (96%). The photocatalytic process occurs because of the presence of OH• radicals. The addition of H₂O₂ led to the inhibition of OH• radicals that H₂O₂ scavenged.

Magnetic Characterization by Scanning Microscopy of Functionalized Iron Oxide Nanoparticles

This study aimed to systematically understand the magnetic properties of magnetite (Fe₃O₄) nanoparticles functionalized with different Pluronic F-127 surfactant concentrations (Fe₃O₄@Pluronic F-127) obtained by using an improved magnetic characterization method based on three-dimensional magnetic maps generated by scanning magnetic microscopy. Additionally, these Fe₃O₄ and Fe₃O₄@Pluronic F-127 nanoparticles, as promising systems for biomedical applications, were prepared by a wet chemical reaction. The magnetization curve was obtained through these three-dimensional maps, confirming that both Fe₃O₄ and Fe₃O₄@Pluronic F-127 nanoparticles have a superparamagnetic behavior. The as-prepared samples, stored at approximately 20 °C, showed no change in the magnetization curve even months after their generation, resulting in no nanoparticles free from oxidation, as Raman measurements have confirmed. Furthermore, by applying this magnetic technique, it was possible to estimate that the nanoparticles' magnetic core diameter was about 5 nm. Our results were confirmed by comparison with other techniques, namely as transmission electron microscopy imaging and diffraction together with Raman spectroscopy. Finally, these results, in addition to validating scanning magnetic microscopy, also highlight its potential for a detailed magnetic characterization of nanoparticles.

Zn Doped α-Fe2O3: An Efficient Material for UV Driven Photocatalysis and Electrical Conductivity

Zinc (Zn) doped hematite (α-Fe2O3) nanoparticles with varying concentrations (pure, 2%, 4% and 6%) were synthesized via sol-gel method. The influence of divalent Zn ions on structural, optical and dielectric behavior of hematite were studied. X-ray diffraction (XRD) pattern of synthesized samples were indexed to rhombohedral R3c space group of hematite with 14–21 nm crystallite size. The lattice parameter (a and c) values increase upto Zn 4% and decrease afterwards. The surface morphology of prepared nanoparticles were explored using transmission electron microscopy (TEM). The band gap measured from Tauc’s plot, using UV-Vis spectroscopy, showed reduction in its values upto Zn 4% and the reverse trend was obtained in higher concentrations. The dielectric properties of pure and Zn doped hematite were investigated at room temperature and followed the same trends as that of XRD parameters and band gap. Photocatalytic properties of nanoparticles were performed for hazardous Rose bengal dye and showed effective degradation in the presence of UV light. Hence, Zn2+ doped hematite can be considered as an efficient material for the potential applications in the domain of photocatalysis and also higher value of dielectric constant at room temperature makes them applicable in high energy storage devices.

C, N dual-doped ZnO nanofoams: a potential antimicrobial agent, an efficient visible light photocatalyst and SXAS studies

It is crucial to develop an environmentally friendly and low-cost method to treat industrial effluent that contains soluble dyes and microbes. Most of the photocatalysts have been studied using an external light source that increases the cost of the purification process of effluent. This study focuses on developing efficient solar photocatalytic nanofoams. The controlled growth of ZnO nanofoams (CNZ nanofoams) in a simple method of thermal oxidation using a soft template is reported. Prepared nanofoams are characterized using X-ray diffraction, scanning electon microscopy and synchrotron soft X-ray absorption spectroscopy. By photocatalysis studies under direct sunlight it was found that within 120 min CNZ nanofoams degraded 99% of the dye. In addition, antimicrobial studies of multi-drug-resistant E. Fergusonii isolated from wastewater was carried out. These antimicrobial results showed a good inhibition zone, indicating that prepared nanofoams are both an effective solar photocatalyst and an antimicrobial agent.

High index facet bounded α-Fe2O3 pseudocubic nanocrystals with enhanced electrochemical properties: Zn2+ ion assisted solvo-hydrothermal synthesis

Pseudocubic α-Fe₂O₃ nanocrystals were grown by a surfactant-free, low temperature, solvo-hydrothermal process and characterised by XRD, FESEM, TEM, FTIR, Raman, XPS and UV-vis analysis.

Sustainable preparation of sunlight active α-Fe2O3 nanoparticles using iron containing ionic liquids for photocatalytic applications

Inspired by the nano-segregation of ionic liquids (ILs) into bi-continuous structures constituting of arrays of ionic and non-ionic components, herein, a new and sustainable strategy for preparation of mesh-like nano-sheet α-Fe₂O₃ nanoparticles and their photo-catalytic activity under sunlight, is presented. For the purpose, metal (iron) containing ionic liquids (MILs), 1-alkyl-3-methylimidazolium tetrachloroferrates, [C_nmim][FeCl₄], (n = 4, 8 and 16), which not only act as precursors and solvents but also as structure directing agents have been used. Thus prepared NPs show MIL dependent structural, photophysical and magnetic properties. The catalytic efficiency of NPs has been tested for the photo-degradation of organic dyes (Rhodamine B) in aqueous solution under sunlight. The NPs are found to exhibit comparable catalytic efficiency under sunlight as compared to that observed under high intensity visible lamplight, without showing a decline in their catalytic efficiency even after 4 catalytic cycles. It is anticipated that the present work will provide a new platform for preparation of sunlight active nanomaterials for photo-catalytic applications with control over the structural and physical properties via varying the molecular structure of MILs.

Inspired by nanosegregation of ionic liquids into bicontinuous structures of arrays of ionic and non-ionic components, we present a new sustainable strategy for preparation of mesh-like nano-sheets of α-Fe₂O₃ nanoparticles and their photocatalytic activity under sunlight.

Microscale flower-like magnesium oxide for highly efficient photocatalytic degradation of organic dyes in aqueous solution

Flower-like MgO microparticles with excellent photocatalytic performance in degradation of various organic dyes were synthesized by a facile precipitation method via the reaction between Mg²⁺ and CO₃²⁻ at 70 °C.

Fabrication and characterization of novel iodine doped hollow and mesoporous hematite (Fe2O3) particles derived from sol-gel method and their photocatalytic performances

In this work, iodine (I) doped hollow and mesoporous Fe₂O₃ photocatalyst particles were fabricated for the first time through sol-gel method. Phase structure, surface morphology, particle size, specific surface area and optical band gap of the synthesized Fe₂O₃ photocatalysts were analyzed by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), X-ray photoelectron spectroscopy (XPS), BET surface analysis, particle size analyzer and UV-vis diffuse reflectance spectrum (UV-vis DRS), respectively. Also, electrochemical properties and photoluminescence spectra of Fe₂O₃ particles were measured. The results illustrated that high crystalline, hollow and mesoporous Fe₂O₃ particles were formed. The optical band gap values of the Fe₂O₃ photocatalysts changed between 2.104 and 1.93eV. Photocatalytic efficiency of Fe₂O₃ photocatalysts were assessed via MB solution. The photocatalytic activity results exhibited that I doping enhanced the photocatalytic efficiency. 1% mole iodine doped (I-2) Fe₂O₃ photocatalyst had 97.723% photodegradation rate and 8.638×10^-2min^-1 kinetic constant which showed the highest photocatalytic activity within 45min. Moreover, stability and reusability experiments of Fe₂O₃ photocatalysts were carried out. The Fe₂O₃ photocatalysts showed outstanding stability after four sequence tests. As a result, I doped Fe₂O₃ is a good candidate for photocatalysts.

Radiation enhanced uptake of Hg0(g) on iron (oxyhydr)oxide nanoparticles

We herein report kinetic studies on UV-visible radiation (315 ≤ λ ≤ 700 nm) enhanced uptake of Hg0(g) by proxies for reactive components of mineral dust (nano γ-Fe₂O₃, α-FeOOH, α-Fe₂O₃ and Fe₃O₄) and propose possible reaction mechanisms.