Striking Stabilization Effect of Spinel Cobalt Oxide Oxygen Evolution Electrocatalysts in Neutral pH by Dual-Sites Iron Incorporation

Developing stable and efficient nonprecious-metal-based oxygen evolution catalysts in the neutral electrolyte is a challenging but essential goal for various electrochemical systems.Particularly,cobalt-based spinels have drawn a considerable amount of attention but most of them operate in alkali solutions.However,the frequently studied Co-Fe spinel system never exhibits appreciable stability in nonbasic conditions,not to mention attract further investigation on its key structural motif and transition states for activity loss.Herein,we report exceptional stable Co-Fe spinel oxygen evolution catalysts(~30%Fe is optimal)in a neutral electrolyte,owing to its unique metal ion arrangements in the crystal lattice.The introduced iron content enters both the octahedral and tetrahedral sites of the spinel as Fe^(2+)and Fe^(3+)(with Co ions having mixed distribution as well).Combining density functional theory calculations,we find that the introduction of Fe to Co_(3)O_(4)lowers the covalency of metal-oxygen bonds and can help suppress the oxidation of Co^(2+/3+)and 0^(2-).It implies that the Co-Fe spinel will have minor surface reconstruction and less lattice oxygen loss during the oxygen evolution reaction process in comparison with Co_(3)O_(4)and hence show much better stability.These findings suggest that there is still much chance for the spinel structures,especially using reasonable sublattices engineering via multimetal doping to develop advanced oxygen evolution catalysts.

Carbon Monoxide Modulates Auxin Transport and Nitric Oxide Signaling in Plants under Iron Deficiency Stress

Carbon monoxide(CO)and nitric oxide(NO)are signal molecules that enhance plant adaptation to environmental stimuli.Auxin is an essential phytohormone for plant growth and development.CO and NO play crucial roles in modulating the plant’s response to iron deficiency.Iron deficiency leads to an increase in the activity of heme oxygenase(HO)and the subsequent generation of CO.Additionally,it alters the polar subcellular distribution of Pin-Formed 1(PIN1)proteins,resulting in enhanced auxin transport.This alteration,in turn,leads to an increase in NO accumulation.Furthermore,iron deficiency enhances the activity of ferric chelate reductase(FCR),as well as the expression of the Fer-like iron deficiency-induced transcription factor 1(FIT)and the ferric reduction oxidase 2(FRO2)genes in plant roots.Overexpression of the long hypocotyl 1(HY1)gene,which encodes heme oxygenase,or the CO donor treatment resulted in enhanced basipetal auxin transport,higher FCR activity,and the expression of FIT and FRO2 genes under Fe deficiency.Here,a potential mechanism is proposed:CO and NO interact with auxin to address iron deficiency stress.CO alters auxin transport,enhancing its accumulation in roots and up-regulating key iron-related genes like FRO2 and IRT1.Elevated auxin levels affect NO signaling,leading to greater sensitivity in root development.This interplay promotes FCR activity,which is crucial for iron absorption.Together,these molecules enhance iron uptake and root growth,revealing a novel aspect of plant physiology in adapting to environmental stress.

High temperature oxidation of inoculated high Si/SiMo ductile cast irons in air and combustion atmospheres

The present work aims to investigate the effect of heating temperature(400,600 and 800°C)and inoculating elements(Ca,Ca-Ba,Ca-RE)on oxidation behavior of ductile irons containing 5.25%Si and 4.8%Si-2.3%Mo in dry air and combustion gas containing water vapour(natural gas burning).The oxidation is influenced by the gas atmosphere type,the iron alloying system,and the inoculating elements depending on the heating temperature.The weight gain increases from 0.001%-0.1%(400°C)to 0.05%-0.70%(600°C)and up to 0.10%-2.15%(800°C).No particular effects of the considered influencing factors are found when heating at 400°C,while at 600°C,mainly the oxidation gas atmosphere type shows a visible influence.At the highest heating temperature of 800°C,a limited increase of the weight gain is found for dry air atmosphere(up to 0.25%),but it drastically increases for combustion atmospheres(0.65%-2.15%).The water vapour presence in the combustion atmosphere is an important oxidising factor at 600-800°C.The alloying system appears to influence the oxidation behavior mainly at a heating temperature of 800°C in the combustion atmosphere,as evidenced by the lower weight gain in 5.25%silicon cast iron.Positive effects of inoculating elements increase with the heating temperature,with Ca and Ba-FeSi inoculation generally showing better performance.Irons inoculated with CaRE-FeSi exhibit a higher degree of oxidation.These results are in good relationship with the previous reported data:Ca-Ba-inoculation system appears to be better than simple Ca for improving the graphite parameters,while RE-bearing inoculant negatively affects the compactness degree of graphite particles in high-Si ductile irons.As the lower compactness degree is typical for graphite nodules in high-Si ductile irons,which negatively affects the oxidation resistance,it is necessary to employ specific metallurgical treatments to improve nodule quality.Inoculation,in particular,is a potential method to achieve this improvement.

A critical review towards the causes of the iron-based catalysts deactivation mechanisms in the selective oxidation of hydrogen sulfide to elemental sulfur from biogas

Hydrogen sulfide(H_(2)S) not only presents significant environmental concerns but also induces severe corrosion in industrial equipment,even at low concentrations.Among various technologies,the selective oxidation of hydrogen sulfide(SOH_(2)S) to elemental sulfur(S) has emerged as a sustainable and environmentally friendly solution.Due to its unique properties,iron oxide has been extensively investigated as a catalyst for SOH_(2)S;however,rapid deactivation has remained a significant drawback.The causes of iron oxide-based catalysts deactivation mechanisms in SOH_(2)S,including sulfur or sulfate deposition,the transformation of iron species,sintering and excessive oxygen vacancy formation,and active site loss,are thoroughly examined in this review.By focusing on the deactivation mechanisms,this review aims to provide valuable insights into enhancing the stability and efficiency of iron-based catalysts for SOH_(2)S.

Efficient degradation of dye pollutants in wastewater via photocatalysis using a magnetic zinc oxide/graphene/iron oxide-based catalyst

In this paper, we present a proof-of-concept study of the enhancement of photocatalytic activity via a combined strategy of fabricating a visible-light responsive ternary heterostructure and improving overall photostability by incorporating magnetic zinc oxide/graphene/iron oxide (ZGF). A solvothermal approach was used to synthesize the catalyst. X-ray diffraction (XRD), scanning electron microscopic, energy dispersive X-ray, transmission electron microscopic, vibrating sample magnetometric, and ultraviolet–visible diffuse reflectance spectroscopic techniques were used to characterize the synthesized samples. The obtained optimal Zn(NO_(3))_(2) concentration, temperature, and heating duration were 0.10 mol/L, 600℃, and 1 h, respectively. The XRD pattern revealed the presence of peaks corresponding to zinc oxide, graphene, and iron oxide, indicating that the ZGF catalyst was effectively synthesized. Furthermore, when the developed ZGF was used for methylene blue dye degradation, the optimum irradiation time, dye concentration, catalyst dosage, irradiation intensity, and solution pH were 90 min, 10 mg/L, 0.03 g/L, 100 W, and 8.0, respectively. Therefore, the synthesized ZGF system could be used as a catalyst to degrade dyes in wastewater samples. This hybrid nanocomposite consisting of zinc oxide, graphene, and iron oxide could also be used as an effective photocatalytic degrader for various dye pollutants.

An amorphous manganese iron oxide hollow nanocube cathode for aqueous zinc ion batteries

Aqueous zinc ion batteries(ZIBs) are attracting considerable attentions for practical energy storage because of their low cost and high safety.Nevertheless,the traditional manganese oxide cathode materials suffer from the low intrinsic electronic conductivity,sluggish ions diffusion kinetics,and structural collapse,hindering their large-scale application.Herein,we successfully developed a latent amorphous Mn_(1.8)Fe_(1.2)O_(4) hollow nanocube(a-H-MnFeO) cathode material derived from Prussian blue analogue precursor.The amorphous nature endows the cathode with lower diffusion barrier and narrower band gap compared with crystalline counterpart,resulting in the superior Zn^(2+) ions and electrons transport kinetics.Hollow structure can furnish abundant surface sites and suppress the structural collapse during the repeated charge/discharge processes.By virtue of the multiple advantageous features,the a-H-MnFeO cathode exhibits exceptional electrochemical performance,in terms of high capacity,excellent rate capability,and prolonged cycle life.This strategy will pave the way for the structural design of emerging cathode materials.

Recent Progress in Superparamagnetic Iron Oxide Nanoparticles

Superparamagnetic iron oxide nanoparticles(SPIONs)have immeasurable potentials in many fields such as nanobiotechnology and biomedical engineering because of their superparamagnetic properties and small particle size.This review introduces the methods for SPIONs synthesis,including co-precipitation,thermal decomposition,microemulsion and hydrothermal reaction,and surface modification of SPIONs with organometallic and inorganic metals,surface modification for targeted drug delivery,and the use of SPIONs as a contrast agent.In addition,this article also provides an overview of recent progress in SPIONs for the treatment of glioma,lung cancer and breast cancer.

Vicious cycle of lipid peroxidation and iron accumulation in neurodegeneration

Lipid peroxidation and iron accumulation are closely associated with neurodegenerative diseases,such as Alzheimer’s,Parkinson’s,and Huntington’s diseases,or neurodegeneration with brain iron accumulation disorders.Mitochondrial dysfunction,lipofuscin accumulation,autophagy disruption,and ferroptosis have been implicated as the critical pathomechanisms of lipid peroxidation and iron accumulation in these disorders.Currently,the connection between lipid peroxidation and iron accumulation and the initial cause or consequence in neurodegeneration processes is unclear.In this review,we have compiled the known mechanisms by which lipid peroxidation triggers iron accumulation and lipofuscin formation,and the effect of iron overload on lipid peroxidation and cellular function.The vicious cycle established between both pathological alterations may lead to the development of neurodegeneration.Therefore,the investigation of these mechanisms is essential for exploring therapeutic strategies to restrict neurodegeneration.In addition,we discuss the interplay between lipid peroxidation and iron accumulation in neurodegeneration,particularly in PLA2G6-associated neurodegeneration,a rare neurodegenerative disease with autosomal recessive inheritance,which belongs to the group of neurodegeneration with brain iron accumulation disorders.

Preparation of Superparamagnetic Dextran-coated Iron Oxide Nanoparticles used as a Novel Gene Carrier into Human Bladder Cancer Cells'

Objective: Application of magnetic nanoparticles as gene carrier in gene therapy has developed quickly. This study was designed to investigate the preparation of superparamagnetic dextran-coated iron oxide nanoparticles (SDION) and the feasibility of SDION used as a novel gene carrier for plasmid DNA in vitro. Methods: SDION were prepared by chemical coprecipitation and separated by gel filtration on Sephacryl S-300HR, characterized by TEM, laser scattering system and Vibrating Sample Magnetometer Signal Processor. The green fluorescent protein (pGFP-C2) plasmid DNA was used as target gene. SDION-pGFP-C2 conjugate compounds were produced by means of oxidoreduction reaction. The connection ratio of SDION and pGFP-C2 DNA was analyzed and evaluated by agarose electrophoresis and the concentration of pGFP-C2 in supernatant was measured. Using liposome as control, the transfection efficiency of SDION and liposome was respectively evaluated under fluorescence microscope in vitro. Results: The diameter of SDION ranges from 3 nm to 8 nm, the effective diameter was 59.2 nm and the saturation magnetization was 0.23 emu/g. After SDION were reasonably oxidized, SDION could connect with pGFP-C2 to a high degree. The transfection efficiency of SDION as gene carrier was higher than that of liposome. Conclusion: The successes in connecting SDION with pGFP-C2 plasmid by means of oxidoreduction reaction and in transferring pGFP-C2 gene into human bladder cancer BIU-87 cells in vitro provided the experimental evidence for the feasibility of SDION used as a novel gene carrier.

Effect of competing solutes on arsenic(Ⅴ) adsorption using iron and aluminum oxides

The study focused on the effect of several typical competing solutes on removal of arsenic with Fe2O3 and Al2O3. The test results indicate that chloride, nitrate and sulfate did not have detectable effects, and that selenium（Ⅳ） （Se（Ⅳ）） and vanadium（Ⅴ） （V（Ⅴ）） showed slight effects on the adsorption of As（Ⅴ） with Fe2O3. The results also showed that adsorption of As（Ⅴ） on A12O3 was not affected by chloride and nitrate anions, but slightly by Se（Ⅳ） and V（Ⅴ） ions. Unlike the adsorption of As（Ⅴ） with Fe2O3, that with Fe2O3 was affected by the presence of sulfate in water solutions. Both phosphate and silica have significant adverse effects on the adsorption of As（Ⅴ） adsorption with Fe2O3 and Al2O3. Compared to the other tested anions, phosphate anion was found to be the most prominent solute affecting the As（Ⅴ） adsorption with Fe2O3 and Al2O3. In general, Fe2O3 has a better performance than Al2O3 in removal of As（Ⅴ） within a water environment where multi competing solutes are present.

Mutual effects of nitric oxide and iron on the growth of marine algae

Experiments on the effects of nitric oxide （NO） and iron on the growth of marine microalgae Skeletonema costatum were conducted. The results are as follows： exogenous NO could increase the growth rate of marine algae and raise the biomass remarkably under iron-deficient conditions. But it was a complicated process that the phytoplankton growth was influenced by NO and iron, which was controlled by the NO concentration, the nutrition level of the culture medium and the iron concentration, etc. Meanwhile, the iron concentration in the medium also has a direct influence on the growth and NO release capacity of the algae. Therefore, the effects of NO and iron on the growth of marine phytoplankton were mutual.

Selective catalytic oxidation of NO over iron and manganese oxides supported on mesoporous silica

The selective catalytic oxidation （SCO） of NO was studied on a catalyst consisting of iron-manganese oxide supported on mesoporous silica （MPS） with different Mn/Fe ratios. Effects of the amount of manganese and iron, oxygen, and calcination temperature on NO conversion were also investigated. It was found that the Mn-Fe/MPS catalyst with a Mn/Fe molar ratio of 1 showed the highest activity at the calcination temperature of 400 °C. The results showed that over this catalyst, NO conversion reached 70% under the condition of 280 °C and a space velocity of 5000 h-1. SO2 and H2O had no adverse impact on the reaction activity when the SCO reaction temperature was above 240 °C. In addition, the SCO activity was suppressed gradually in the presence of SO2 and H2O below 240 °C, and such an effect was reversible after heating treatment.

Reduction kinetics of iron oxide pellets with H_2 and CO mixtures

Reduction of hematite pellets using H2-CO mixtures with a wide range of H2/CO by molar （1：0, 3：1, 1：1, 1：3, and 0：1） at different reducing temperatures （1073, 1173, and 1273 K） was conducted in a program reducing furnace. Based on an unreacted core model, the effective diffusion coefficient and reaction rate constant in several cases were determined, and then the rate-control step and transition were analyzed. In the results, the effective diffusion coefficient and reaction rate constant increase with the rise in temperature or hydrogen content. Reduction of iron oxide pellets using an H2-CO mixture is a compound control system; the reaction rate is dominated by chemical reaction at the very beginning, competition during the reduction process subsequently, and internal gas diffusion at the end. At low hydrogen content, increasing temperature takes the transition point of the rate-control step to a high reduction degree, but at high hydrogen content, the effect of temperature on the transition point weakens.

Ceramsite Containing Iron Oxide and its Use as Functional Aggregate in Microwave Absorbing Cement-based Materials

Electromagnetic（EM） wave absorbing cement-based composite has promising applications in protecting civil and military buildings from electromagnetic interferences. A new idea of preparing EM wave absorbing cement-based composite is proposed by using ceramsite containing iron oxide as EM wave absorbing functional aggregate. The ceramsite was synthesized by adding 10 wt% Fe3O4 into clay and sintering at 1 200 ℃, which shows obvious dielectric and magnetic loss properties for electromagnetic wave. The maximum reflection loss（RL） of the concrete specimens prepared with the ceramsite is between-10.2--10.7 dB（corresponding to absorption greater than 90% EM energy） in the bandwidth of 8-18 GHz. In addition, the compressive strength at 28 days age of the concrete is 46 MPa, showing the potentiality of being used as structural components in buildings.

Characterization of Iron Oxide Generated in Ruthner Plant of Pickling Unit in Mobarakeh Steel Complex

Reducing the chloride content in regenerated iron oxides (RIO) from steel-pickling acid waste economically treated by Ruthner process is the most critical issue for the development of RIO as a useful raw material resource. In this paper, the results of a new method for characterization and modification of RIO produced in Mobarakeh Steel Complex were reported.

Staged reaction kinetics and characteristics of iron oxide direct reduction by carbon

Staged reduction kinetics and characteristics of iron oxide direct reduction by carbon were studied in this work. The characteristics were investigated by simultaneous thermogravimetric analysis, X-ray diffraction（XRD）, and quadrupole mass spectrometry. The kinetics parameters of the reduction stages were obtained by isoconversional（model-free） methods. Three stages in the reduction are Fe2O3→Fe3O4, Fe3O4→Fe O, and Fe O→Fe, which start at 912 K, 1255 K, and 1397 K, respectively. The CO content in the evolved gas is lower than the CO2content in the Fe2O3→Fe3O4stage but is substantially greater than the CO2 contents in the Fe3O4→Fe O and Fe O→Fe stages, where gasification starts at approximately 1205 K. The activation energy（E） of the three stages are 126–309 k J/mol, 628 k J/mol, and 648 k J/mol, respectively. The restrictive step of the total reduction is Fe O→Fe. If the rate of the total reduction is to be improved, the rate of the Fe O→Fe reduction should be improved first. The activation energy of the first stage is much lower than those of the latter two stages because of carbon gasification. Carbon gasification and FexOy reduction by CO, which are the restrictive step in the last two stages, require further study.

The production of iron oxide during peridotite serpentinization:Influence of pyroxene

Serpentinization produces molecular hydrogen(H2)that can support communities of microorganisms in hydrothermal fields;H2 results from the oxidation of ferrous iron in olivine and pyroxene into ferric iron,and consequently iron oxide(magnetite or hematite)forms.However,the mechanisms that control H2 and iron oxide formation are poorly constrained.In this study,we performed serpentinization experiments at 311℃ and 3.0 kbar on olivine(with <5% pyroxene),orthopyroxene,and peridotite.The results show that serpentine and iron oxide formed when olivine and orthopyroxene individually reacted with a saline starting solution.Olivine-derived serpentine had a significantly lower FeO content(6.57±1.30 wt.%)than primary olivine(9.86 wt.%),whereas orthopyroxene-derived serpentine had a comparable FeO content(6.26±0.58 wt.%)to that of primary orthopyroxene(6.24 wt.%).In experiments on peridotite,olivine was replaced by serpentine and iron oxide.However,pyroxene transformed solely to serpentine.After 20 days,olivine-derived serpentine had a FeO content of 8.18±1.56 wt.%,which was significantly higher than that of serpentine produced in olivine-only experiments.By contrast,serpentine after orthopyroxene had a slightly higher FeO content(6.53±1.01 wt.%)than primary orthopyroxene.Clinopyroxene-derived serpentine contained a significantly higher FeO content than its parent mineral.After 120 days,the FeO content of olivine-derived serpentine decreased significantly(5.71±0.35 wt.%),whereas the FeO content of orthopyroxene-derived serpentine increased(6.85±0.63 wt.%)over the same period.This suggests that iron oxide preferentially formed after olivine serpentinization.Pyroxene in peridotite gained some Fe from olivine during the serpentinization process,which may have led to a decrease in iron oxide production.The correlation between FeO content and SiO_2 or AI_2 O_3 content in olivine-and orthopyroxene-derived serpentine indicates that aluminum and silica greatly control the production of iron oxide.Based on our results and data from natural serpentinites reported by other workers,we propose that aluminum may be more influential at the early stages of peridotite serpentinization when the production of iron oxide is very low,whereas silica may have a greater control on iron oxide production during the late stages instead.

Effects of Catalyst and Additive Containing Li, Na, or Ca on Reduction of Iron Oxide/Carbon Composite Pellets

The catalyst containing 0.69% (mass fraction) of Li+, Na+, or Ca2+ were synthesized, and the catalytic effect on the reduction of iron oxide/carbon composite pellets were investigated by comparing with that of additive at 850 degreesC. The effect of the catalyst was greater than that of the additive, it can be considered that catalyst promoted the formation of iron nucleus early on reduction processes of iron oxide/carbon composite pellets. In addition, both effects of catalyst and additive increased after added carbon powder into the pellets, but the extent of increase decreased when the carbon powder exceeded a suitable content (about 4%), this amount is less than that of carbon needed theoretically on the reduction from hematite to iron.

Study on Kinetics of Iron Oxide Reduction by Hydrogen

Kinetics parameters of iron oxide reduction by hydrogen were evaluated by the isothermal method in a differential micro-packed bed. Influence of external diffusion, internal diffusion and heat transfer on the intrinsic reaction rate was investigated and the conditions free of internal and external diffusion resistance have been determined. In the experiments, in order to correctly evaluate the intrinsic kinetics parameters for reducing Fe203 to Fe3O4, the reaction temperatures were set between 440 ℃ and 490 ℃. However, in order to distinguish the reduction of Fe304 to FeO from that of FeO to Fe, the reaction temperature in the experiment was set to be greater than 570 ℃. Intrinsic kinetics of iron oxide reduction by hydrogen was established and the newly established kinetic models were validated by the experimental data.

Exogenous Nitric Oxide Alleviated the Inhibition of Photosynthesis and Antioxidant Enzyme Activities in Iron-Deficient Chinese Cabbage (Brassica chinensis L.)

The effects of exogenous nitric oxide （NO） on plant growth, chlorophyll contents, photosynthetic and chlorophyll fluorescence parameters as well as lipid peroxidation and activities of antioxidant enzymes were investigated in Chinese cabbage plants exposed to iron （Fe） deficiency. Iron deficiency led to serious chlorosis in Chinese cabbage leaves, and resulted in significant decrease in plant growth, photosynthetic pigments, net photosynthetic rate, Fv/Fm, Ф ps Ⅱ and activities of antioxidant enzymes, and increase in lipid peroxidation. While treatment with SNP, a NO donor, it could revert the iron deficiency symptoms, increased photosynthetic rate as well as activities of antioxidant enzymes, and protected membrane from lipid peroxidation, as a result, the growth inhibition of Chinese cabbage by Fe deficiency was alleviated.