Iron Oxyhydroxide Nanoparticles Research Articles

Sulfate enhances the adsorption and retention of Cu(II) and Zn(II) to dispersed and aggregated iron oxyhydroxide nanoparticles

The adsorption and retention of metal ions to nanoscale iron (hydr)oxides in aqueous systems is significantly influenced by prevailing environmental conditions. We examined the influence of sulfate, the second most common anion in seawater that is present in many other natural aquatic systems, on the adsorption and retention of Cu(II) and Zn(II) to synthetic iron oxyhydroxide nanoparticles (NPs) and their aggregates. Batch uptake experiments with monodisperse NPs and NPs aggregated by changes in pH, ionic strength, and temperature were conducted over sulfate concentrations ranging from 0 to 0.30 M. The introduction of 0.03 M sulfate significantly increased the initial adsorption and retention of Zn(II) and Cu(II) compared to sulfate-free conditions; with increasing sulfate >0.03 M, Zn(II) retention continuously increased, while Cu(II) retention was considerably more variable but increased slightly. NP aggregation, when induced by pH and ionic strength, was positively correlated with metal ion retention, while aggregation temperature was negatively correlated with both adsorption and retention. Aqueous geochemical modeling indicated that Zn(II) readily complexes with sulfate to form ZnSO4 (aq), but that stable aqueous CuSO4 species are uncommon. EXAFS spectroscopic analysis suggests structural incorporation of Zn(II) and Zn(II)-sulfate ternary surface complexation, while Cu(II) primarily forms inner-sphere bidentate surface complexes. Collectively, the effects of sulfate in both reducing surface charge repulsion, initiating ternary surface complexation, and enabling structural incorporation aid to enhance both metal adsorption and retention to iron oxyhydroxide NPs and their aggregates.

Biosynthesis and characterization of α-FeOOH nanoparticles using Isabella grape (Vitis Labrusca L.) extract

The advancement of environmentally sustainable and eco-friendly approaches to nanoparticle synthesis has gained significant importance in analytical chemistry. This research examined the green synthesis of iron oxyhydroxide nanoparticles, utilizing Vitis labrusca L. extract as both a reducing and stabilizing agent. The application of this natural extract offers an environmentally friendly alternative to conventional chemical synthesis techniques and is expected to meet the growing demand for sustainable applications. The synthesized iron oxyhydroxide nanoparticles were characterized using advanced techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FT-IR), to verify their composition and structure. The findings reveal the successful synthesis of iron oxyhydroxide nanoparticles with a uniform size distribution and excellent stability.

Efficient and durable S-doped Ni/FeOOH electrocatalysts for oxygen evolution reactions.

It is important to develop highly efficient and durable Earth-abundant oxygen evolution reaction (OER) electrocatalysts by an energy- and time-saving strategy. Herein, a facile strategy was used to synthesize S-doped nickel-iron oxyhydroxide (S-Ni/FeOOH) nanoparticles on nickel-iron foam (NFF) (S-Ni/FeOOH@NFF), which exhibits a striking enhancement of OER performance compared to Ni/FeOOH@NFF. The free-standing S-Ni/FeOOH@NFF electrode possesses a low overpotential of 229 mV at a current density of 10 mA cm-2, which is 180 mV lower than that of Ni/FeOOH@NFF. In addition, the electrode was also remarkably stable. The current density still remains at 95% after 150 h at a high current density of 100 mA cm-2.

A Comprehensive Study of Synthesis and Analysis of Anisotropic Iron Oxide and Oxyhydroxide Nanoparticles.

One-dimensional anisotropic nanoparticles are of great research interest across a wide range of biomedical applications due to their specific physicochemical and magnetic properties in comparison with isotropic magnetic nanoparticles. In this work, the formation of iron oxides and oxyhydroxide anisotropic nanoparticles (ANPs) obtained by the co-precipitation method in the presence of urea was studied. Reaction pathways of iron oxide and oxyhydroxide ANPs formation are described based on of X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and pulse magnetometry studies. It is shown that a nonmonotonic change in the Fe3O4 content occurs during synthesis. The maximum content of the Fe3O4 phase of 47.4% was obtained at 12 h of the synthesis. At the same time, the reaction products contain ANPs of α-FeOOH and submicron isotropic particles of Fe3O4, the latter formation can occur due to the oxidation of Fe2+ ions by air-oxygen and Ostwald ripening processes. A subsequent increase in the synthesis time leads to the predominant formation of an α-FeOOH phase due to the oxidation of Fe3O4. As a result of the work, a methodological scheme for the analysis of iron oxide and oxyhydroxide ANPs was developed.

Optimization of Synthesis Conditions of β-FeOOH Nanorods towards Antimicrobial Benefits

FeOOH nanoparticles have recently appealed to wide-ranging applications due to their physicochemical properties and size-tunable synthesis; however, a few studies were performed on the antimicrobial potentials of iron oxyhydroxide nanoparticles. In this regard, we aimed to design various synthesis experiments to optimize the fabrication of β-FeOOH nanorods (NRs) with a desirable size of NRs and high antimicrobial potential. For this purpose, ten experiments were designed by manipulating reaction conditions of the standard hydrolysis method, including the initial concentration of ferric ions, reaction time, reaction temperature, and different concentrations of surfactants of PEI and PEG as process control agents. The structural characteristics of prepared NRs were analyzed using FE-SEM, FTIR, and XRD. The ImageJ software was also used to measure the length, width, and aspect ratio of NRs. Five microbial species, including the Gram-positive and Gram-negative bacteria and fungi species, were applied to investigate the antimicrobial potentials of NRs. The initial concentration of ferric ions revealed a dominant effect in NRs’ morphology, though other reaction conditions also played essential roles. The crystal structure of NRs was preserved in all synthesis experiments (β-phase) due to using the same iron salt precursors. The synthesized NRs exhibited dose-dependent antimicrobial activities against all tested microbial species. Additionally, the presence of surfactants exhibited an excellent capability of controlling effects on the size and growth pattern of NR crystals and improving their antimicrobial potentials; PEI could also be more effective on the antimicrobial efficacy of final NRs. Besides, our findings exhibited an inverse correlation between aspect ratio and antimicrobial potentials of β-FeOOH NRs. To sum up, it seems that optimization of synthesis conditions could provide tunable size and structure patterns of β-FeOOH NRs to achieve a promising tool for biomedical applications, particularly in combat with resistant microbial species, though further studies are needed in this regard.

Triple action of FeCl3-assisted hydrothermal treatment of digested sludge for deep dewatering

In this study, a FeCl3-assisted hydrothermal treatment (HTT) process under mild conditions (90 °C–130 °C) was developed for deep dewatering of anaerobically digested sludge. HTT of sludge at 90 °C–130 °C with 4%–6% Fe3+ ions loading based on total sludge solids followed by mechanical dewatering reduced sludge water content from 82% to 38%–53% and sludge weight by 62%–72%. The treatment increased the flowability of sludge through reduction of apparent viscosity and disintegration of colloidal forces between sludge particles. This study unveiled that FeCl3-assisted HTT process had three mechanisms for improving sludge dewaterability and flowability. The treatment hydrolysed sludge flocs in the presence of Lewis acid FeCl3 and high temperature (90–130 °C). Fe3+ ions also improved dewaterability through the formation of double electric layers and neutralisation of surface negative charges, leading to flocculation of sludge flocs. More importantly, the hydrolysed sludge components produced during HTT process acted as reducing agents and led to in-situ generation of iron oxyhydroxide nanoparticles through reduction-oxidation reactions, further enhancing flocculation/co-precipitation of sludge flocs. The treatment reduced EPS content and changed conformational structures of EPS proteins by breaking down hydrogen bond-maintaining α-helix which led to a loose EPS protein structure and enhanced hydrophobicity and flocculability. Furthermore, the FeCl3-assisted treatment promoted immobilisation of the majority of heavy metals in the sludge matrix through co-precipitation/complexation reactions with iron species and organic/inorganic matters. This indicates that the FeCl3-assisted treatment reduced direct toxicity/bioavailability of the majority of heavy metals and the treated sludge may be suitable for land application. Overall, this study provides new insights into mechanism of FeCl3-assisted HTT process for dewaterability of anaerobically digested sludge and immobilisation of heavy metals.

Iron oxide and iron oxyhydroxide nanoparticles impair SARS-CoV-2 infection of cultured cells

BackgroundCoronaviruses usually cause mild respiratory disease in humans but as seen recently, some human coronaviruses can cause more severe diseases, such as the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the global spread of which has resulted in the ongoing coronavirus pandemic.ResultsIn this study we analyzed the potential of using iron oxide nanoparticles (IONPs) coated with biocompatible molecules like dimercaptosuccinic acid (DMSA), 3-aminopropyl triethoxysilane (APS) or carboxydextran (FeraSpin™ R), as well as iron oxyhydroxide nanoparticles (IOHNPs) coated with sucrose (Venofer®), or iron salts (ferric ammonium citrate -FAC), to treat and/or prevent SARS-CoV-2 infection. At non-cytotoxic doses, IONPs and IOHNPs impaired virus replication and transcription, and the production of infectious viruses in vitro, either when the cells were treated prior to or after infection, although with different efficiencies. Moreover, our data suggest that SARS-CoV-2 infection affects the expression of genes involved in cellular iron metabolism. Furthermore, the treatment of cells with IONPs and IOHNPs affects oxidative stress and iron metabolism to different extents, likely influencing virus replication and production. Interestingly, some of the nanoparticles used in this work have already been approved for their use in humans as anti-anemic treatments, such as the IOHNP Venofer®, and as contrast agents for magnetic resonance imaging in small animals like mice, such as the FeraSpin™ R IONP.ConclusionsTherefore, our results suggest that IONPs and IOHNPs may be repurposed to be used as prophylactic or therapeutic treatments in order to combat SARS-CoV-2 infection.Graphical

Iron oxyhydroxide nanoparticles: green synthesis and their cytotoxicity activity against A549 human lung adenocarcinoma cells

Iron oxyhydroxide (α-FeOOH, Goethite) is one of the most thermodynamically stable iron oxides and a widespread soil mineral. In this study, a mixture of two phenolic extracts of rosemary and Echinacea was utilized as stabilizing and reducing agents for the synthesis of Goethite (FeOOH) nanoparticles without utilizing harmful toxic solvents. The resulting nanoparticles were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM)-energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), vibrating-sample magnetometer (VSM), thermogravimetry/differential thermal analysis (TG/DTA), and Brunauer–Emmett-Teller (BET). MTT assay was applied for evaluating the possible toxicity of the nanoparticles against A549 human lung adenocarcinoma cells.

Iron rich self-assembly micelles on the Doce River continental shelf

After the Fundão iron ore mining dam rupture in November 2015, yellow/ocher emulsions never before reported on the continental shelf adjacent to the Doce River began to be seen, both in coalesced and foam forms. XRD analyses pointed to a prevailing composition of iron and kaolinite with a substantial contribution of an organic-metallic compound, measured in multiple periods over 2 years of sampling. Optical microscopy images allowed the identification of micelles composed of nanoparticles of iron oxyhydroxide making up this emulsion. The generation of dendritic snowflake-shaped microcrystals on fiber filters after water sample filtration and heating confirmed the presence of micelles composed of iron oxyhydroxide nanoparticles enveloped by organic polymers. After losing water, the micelles may act as a self-assembly template seed, where the polymer acts in the oriented adsorption of nanoparticles according to their crystallographic structure. The study brought to light the distinct behavior of a portion of the tailings material, which has already been reported to not have the same flocculation process as the clay minerals previously found in the suspended particulate material (SPM) before the dam rupture.

Formulation of Iron Oxide and Oxy-hydroxide Nanoparticles from Ilmenite Sand through a Low-Temperature Process.

In our previous publication, we published a simple, low-cost, and environmentally friendly process for the breaking down of the ilmenite lattice using rotary autoclaving, separation of titanium and iron components, and the conversion of the titanium component to amorphous TiO2 and phase-specific titanium dioxide nanorods. Here, the separated iron component was converted into iron oxide (magnetite and hematite) and iron oxy-hydroxide (akaganeite, β-FeOOH) nanoparticles. The process flow diagram is presented to explain the steps involved. The materials synthesized are fully characterized by X-ray diffractogram (XRD), scanning electron microscopy coupled with energy-dispersive X-ray analysis (SEM-EDAX), and Fourier transform infrared (FT-IR), and it is shown that they contain 100% pure iron oxide and iron oxy-hydroxide nanoparticles without any detectable impurities. All of the chemical reactions involved in this process, which contribute to the mechanism of the process, are given. So far, such a low-cost, environmentally friendly, and low-temperature process has not been documented, and the process can be scaled-up for mass production of these nanomaterials used in various technological applications.

An antiviral trap made of protein nanofibrils and iron oxyhydroxide nanoparticles.

Minimizing the spread of viruses in the environment is the first defence line when fighting outbreaks and pandemics, but the current COVID-19 pandemic demonstrates how difficult this is on a global scale, particularly in a sustainable and environmentally friendly way. Here we introduce and develop a sustainable and biodegradable antiviral filtration membrane composed of amyloid nanofibrils made from food-grade milk proteins and iron oxyhydroxide nanoparticles synthesized in situ from iron salts by simple pH tuning. Thus, all the membrane components are made of environmentally friendly, non-toxic and widely available materials. The membrane has outstanding efficacy against a broad range of viruses, which include enveloped, non-enveloped, airborne and waterborne viruses, such as SARS-CoV-2, H1N1 (the influenza A virus strain responsible for the swine flu pandemic in 2009) and enterovirus 71 (a non-enveloped virus resistant to harsh conditions, such as highly acidic pH), which highlights a possible role in fighting the current and future viral outbreaks and pandemics.

Alkali concentration effects on the composition, morphology and magnetic properties of magnetite, maghemite and iron oxyhydroxide nanoparticles

Iron oxide nanoparticles were obtained by co-precipitation from mixed iron salts and ammonium hydroxide (NH4OH) solutions. In this paper, solutions with different concentrations of ammonium hydroxide were used and its effect on composition and morphology were analyzed. Detailed morphological studies from transmission electron microscopy images reveal the presence of two different shapes: spheroidal and elongated nanoparticles. The samples produced with low concentrations of NH4OH showed elongated shapes in the order of 100 nm and 10 nm (length & width), and the samples produced with high concentrations of NH4OH exhibit a homogeneous size distribution of spheroidal particles of the order of 10 nm diameter. The structural analysis from x-ray diffraction elucidates the presence of different phases for samples produced with different alkali concentrations. From vibrating sample magnetometer measurements and Mössbauer spectroscopy on samples produced with high and low alkali concentrations, superparamagnetic and paramagnetic behavior was respectively observed. The magnetic nanoparticles production procedure presented here will not only be used in cutting-edge research but will also serve as a teaching tool to introduce undergraduate, master's and Ph.D. students.

Ion reduction in iron oxide and oxyhydroxide nanoparticles during ultrasonic treatment

The effect of ultrasonic treatment of iron oxide and iron oxyhydroxide nanoparticles (ferrihydrite nanoparticles synthesized by Klebsiella oxytoca microorganisms, ferrihydrite nanoparticles synthesized by a chemical method and hematite nanoparticles) is studied. Samples of nanoparticles were investigated using transmission electron microscopy, Mössbauer spectroscopy and X-ray diffraction methods. The formation of the α-Fe metal phase from nanoparticles of iron oxides and iron oxyhydroxides was detected. The metal phase is formed as a result of the reduction of iron ions during cavitation treatment. According to the experimental results, the presence of a protein or a polysaccharide component is necessary for the course of this reaction.

Effect of sucrose-bound polynuclear iron oxyhydroxide nanoparticles on the efficiency of electron transport in the photosystem II membranes.

Effect of water-soluble and stable sucrose-bound iron oxyhydroxide nanoparticles [Fe[III] sucrose complex (FSC)] on the efficiency of electron transport in the photosystem II membranes was studied. FSC significantly increases (by a factor 1.5) the rate of light-induced oxygen evolution in the presence of alternative electron acceptor 2,6-dichloro-p-benzoquinone (DCBQ). Without DCBQ, FSC only slightly (5%) provides the oxygen evolution. Electron transport supported by pair DCBQ + FSC is inhibited by diuron. Maximum of stimulating effect was recorded at Fe(III) concentration 5µM. In the case of another benzoquinone electron acceptor (2-phenyl-p-benzoquinone and 2,3-dimethyl-p-benzoquinone) and 2,6-dichlorophenolindophenol, stimulating effect of FSC was not observed. Incubation of PSII membranes at different concentrations with FSC is accompanied by binding of Fe(III) by membrane components but only about 50% of iron can be extracted by membranes from Fe(III) solution at pH 6.5. This result implies the heterogeneity of FSC solution in a buffer. The heterogeneity depends on pH and decreases with its rising. At pH around 9.0 Fe(III), sucrose solution is homogeneous. The study of pH effect has shown that stimulation of electron transport is induced only by iron cations which can be bound by membranes. Not extractable iron pool cannot activate electron transfer from oxygen-evolving complex to DCBQ.

Fate and bioavailability of phosphorus loaded to iron oxyhydroxide nanoparticles added to weathered soils

The low phosphorus (P) fertilizer use efficiency in weathered, P deficient soils calls for better fertilizer formulations. We previously formulated nanoparticles containing P (NP-P) that were a successful fertilizer in nutrient solution. This study was set up to test the fate and the bioavailability of nanofertilizer-P and of that of native (colloid) P naturally present in soil. The NP-P consisted of nano-ferrihydrite (~ 10 nm) loaded with phosphate (P-nFh) and stabilized with either natural organic matter (NOM) or hexametaphosphate (HMP). Natural colloid concentrations were increased with KOH addition, as deflocculating agent, to soil; all tests used samples from P deficient, highly weathered soils. Pot trials with rice seedlings did not reveal larger P uptake in the NP-P amended soils compared to equal doses of soluble PO4 or soluble HMP. Total Fe concentrations in soil solutions were unaffected by NP-P addition, whereas natural colloidal Fe and P markedly increased by KOH addition. The bioavailability of native colloidal P, mobilized by KOH addition, could not be assessed due to lack of growth, likely related to collapse of the soil structure. This study showed that P-loaded iron oxyhydroxide NPs insufficiently enhanced soluble P in soil to offer benefits over soluble fertilizers, likely because of a combined effect of lower diffusivity of NPs compared to Pi and lower bioavailability of NP-P than Pi. Smaller particles or small labile organic colloids might offer an improvement in both aspects.

Controlled synthesis of iron oxyhydroxide (FeOOH) nanoparticles using secretory compounds from Chlorella vulgaris microalgae

ABSTRACT FeOOH nanoparticles are commonly synthesized at very high temperature and pressure that makes the process energy consuming and non-economic. Recently, novel approaches were developed for the fabrication of these particles at room temperature. But, the main problem with these methods is that the prepared structures are aggregates of ultra-small nanoparticles where no intact separate nanoparticles are formed. In this study, for the first time, secretory compounds from Chlorella vulgaris cells were employed for the controlled synthesis of FeOOH nanoparticles at room atmosphere. Obtained particles were found to be goethite (α-FeO(OH)) crystals. Controlled synthesis of FeOOH nanoparticles resulted in uniform spherical nanoparticles ranging from 8 to 17 nm in diameter with 12.8 nm mean particle size. Fourier-transform infrared and elemental analyses were indicated that controlled synthesized nanoparticles have not functionalized with secretory compounds of C. vulgaris, and these compounds just played a controlling role over the synthesis reaction.

Incorporation of iron oxyhydroxide nanoparticles in polyacrylonitrile nanofiltration membrane for improving water permeability and antifouling property

In this study, polyacrylonitrile nanofiltration membranes containing two Fe-based nanoparticles were fabricated through phase inversion method by incorporation of goethite (Goe) and maleate ferroxane (Mf), separately in casting solutions. Goe and Mf nanoparticles were first synthesized and characterized by scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR) spectrometer, and X-ray diffraction (XRD) analyses. The synthesized membranes were characterized by SEM, FTIR-attenuated total reflectance (FTIR-ATR), atomic force microscopy (AFM), water contact angle (CA), and porosity measurements. The nanofiltration performance of membranes was studied by investigation of dye removal. Composite membranes showed better dye retention as compared with pristine PAN due to the higher repulsive force between dye and nanocomposite membrane functional groups. The presence of nanoparticles in the PAN membranes decreased CA, increased permeated water flux (PWF), and bulk water affinity (BWA). The reason of these changes was improvement in the surface hydrophilicity and decreasing the surface roughness. The addition of nanoparticles resulted in reduction of fouling phenomenon. Composite membranes had higher reversible fouling and flux recovery ratio (FRR) than bare membranes. In addition, the results displayed that the 0.5 wt% Mf membrane had the best performance among other membranes. FTIR-ATR analysis demonstrated the stability of nanoparticles after three times of dye rejection. Also, the membranes retained the acceptable performance after four cycles of powder milk fouling tests.

Assembly of Protein Stacks With in Situ Synthesized Nanoparticle Cargo.

The ability of proteins to form hierarchical structures through self-assembly provides an opportunity to synthesize and organize nanoparticles. Ordered nanoparticle assemblies are a subject of widespread interest due to the potential to harness their emergent functions. In this work, the toroidal-shaped form of the protein peroxiredoxin, which has a pore size of 7 nm, was used to organize iron oxyhydroxide nanoparticles. Iron in the form of Fe2+ was sequestered into the central cavity of the toroid ring using metal-binding sites engineered there and then hydrolyzed to form iron oxyhydroxide particles bound into the protein pore. By precise manipulation of the pH, the mineralized toroids were organized into stacks confining one-dimensional nanoparticle assemblies. We report the formation and the procedures leading to the formation of such nanostructures and their characterization by chromatography and microscopy. Electrostatic force microscopy clearly revealed the formation of iron-containing nanorods as a result of the self-assembly of the iron-loaded protein. This research bodes well for the use of peroxiredoxin as a template with which to form nanowires and structures for electronic and magnetic applications.

Mineralogy and physicochemical features of Saharan dust wet deposited in the Iberian Peninsula during an extreme red rain event

Abstract. The mineralogy and physicochemical features of Saharan dust particles help to identify source areas and determine their biogeochemical, radiative, and health effects, but their characterization is challenging. Using a multianalytical approach, here we characterized with unprecedented level of detail the mineralogy and physicochemical properties of Saharan dust particles massively wet deposited ( ∼ 18 g m−2) following an extreme red rain event triggered by a northern African cyclone that affected the southern Iberian Peninsula during 21–23 February 2017. Abundant palygorskite and illite, and relatively high carbonate contents, well-known northern and north-western Saharan dust indicators, along with low chlorite content and significant amounts of smectites and kaolinite, whose abundance increases southwards in the western Sahara, complemented by satellite imagery and back/forward trajectories, show that the most probable dust source areas were (i) southern/central Algeria, northern Mali, and northwestern Niger, and (ii) northern Algeria, southern Tunisia, and northwestern Libya. Scanning and transmission electron microscopy analyses, including Z-contrast high angle annular dark field (HAADF) imaging and analytical electron microscopy (AEM), show that clay minerals include abundant structural Fe (55 % of the total Fe) and typically form nanogranular aggregates covered or interspersed with amorphous/poorly crystalline iron oxyhydroxide nanoparticles (ferrihydrite), which account for ∼ 18 % of the free Fe, the rest being goethite and hematite. These nanogranular aggregates tend to form rims lining large silicate and carbonate particles. Such internally mixed iron-containing phases are the main contributors to the observed absorption of solar and thermal radiation, and along with the abundant coarse/giant particles ( > 10 µm) strongly affect the dust direct radiative forcing. The lack of secondary sulfates in aggregates of unaltered calcite internally mixed with clays/iron-rich nanoparticles shows that iron-rich nanoparticles did not form via atmospheric (acid) processing but were already present in the dust source soils. Such iron-rich nanoparticles, in addition to iron-containing clay (nano)particles, are the source of the ∼ 20 % soluble (bioavailable) iron in the studied desert dust. The dust particles are a potential health hazard, specifically the abundant and potentially carcinogenic iron-containing palygorskite fibers. Ultimately, we show that different source areas are activated over large desert extensions, and large quantities of complex dust mixtures are transported thousands of kilometers and wet-deposited during such extreme events, which dwarf any other Saharan dust event affecting southwestern Europe. The past, present, and future trends, as well as impacts, of such extreme events must be taken into account when evaluating and modeling the manifold effects of the desert dust cycle.

Chemical transformation of iron alkoxide nanosheets to FeOOH nanoparticles for highly active and stable oxygen evolution electrocatalysts

We describe a facile chemical transformation method to produce small iron oxyhydroxide (FeOOH) nanoparticles for application in electrochemical oxygen evolution reaction (OER). In this work, iron alkoxide nanosheets were synthesized by heating a mixture of iron nitrate, ethylene glycol (EG), and oleylamine (OAm), which transformed to FeOOH nanoparticles with sizes less than 10nm upon alkali treatment in aqueous KOH solution. These FeOOH nanoparticles exhibited much enhanced OER activity compared with that of both commercial FeOOH powders and IrO2 catalyst, as well as good stability in high pH conditions.