Amount Of Fe Doping Research Articles

Boosting the visible light photo-thermal catalytic performance of α-Bi2O3 by tuning Fe doping amount in carbonylation of isobutyl amine with CO2

CO2 capture and utilization are viewed as the attractive route to promote carbon neutrality. The α-Bi2O3 as a high-performance catalyst of the carbonylation of isobutyl amine with CO2 has been reported in our previous work. Herein, Fe-doped α-Bi2O3 with different molar ratios of Fe/Bi (Fex%-Bi2O3, x = 1, 3, 5, and 7:100) are further successfully synthesized and used firstly as photo, thermal and photo-thermal catalysts in the carbonylation of isobutyl amine with CO2 to N,N′-diisobutylurea. The result demonstrates the catalytic abilities of α-Bi2O3 are significantly boosted by Fe doping and follows an order of Fe5%-Bi2O3 > Fe3%-Bi2O3≫Fe1%-Bi2O3 > Fe7%-Bi2O3 > Fe0%-Bi2O3. Such differences in photo-thermal catalytic performances of Bi2O3 with different Fe doping amounts could be closely linked with the content of both oxygen vacancies and new impurity energy levels in Fex%-Bi2O3 based on the further analysis of characterization such as XRD, SEM, Raman, BET, XPS, EPR, UV–vis, PL and TPC.

Study on the preparation of LiMn1-xFexPO4/C from pyrolusite based on first-principles and its electrochemical properties

In this paper, manganese is used as a medium to connect pyrolusite with lithium-ion batteries, which not only meets the needs of comprehensive utilization of global strategic mineral resources, but also maximizes the performance of lithium-ion batteries under the goal of global carbon neutralization and carbon peak. Firstly, the optimum experimental conditions for sulfuric acid roasting of pyrolusite were investigated by single factor experiment and orthogonal experiment: the roasting temperature was 650 °C, the roasting time was 4 h, the acid-to-ore ratio was 2:1, and the water-to-ore ratio was 0.6:1. The roasting temperature plays a major role. Then, LMFxP-C (x = 0, 1/4, 1/8, 1/12, 1/24) cathode materials were prepared by adding different mass Fe elements with manganese element purified from pyrolusite as manganese source. Its electrochemical analysis was carried out: the capacity retention rate of LMF1/4P–C cathode material is 92.54% after 500 cycles. After a total of 150 times of rate tests at different rates, the discharge specific capacity of LMF1/4P–C can still reach 148.5 mAh g−1. At the same time, the EIS results show that the values of Re and Rct of LMF1/4P–C cathode material are the smallest compared with other materials. Finally, the LMFxP-C cathode material was analyzed by first-principles, and the optimal Fe doping amount was theoretically predicted. The crystal structure, bonding and density of states of the LMFxP-C cathode material were calculated and discussed. The results show that when the Fe doping amount is 1/4, the LMFxP-C system has the highest conductivity and the best electrochemical performance. The calculation results are consistent with the experimental results.

Nitrogen‐Enriched Porous Carbon Materials from Expanded Polystyrene Waste for Oxygen Reduction Reaction and Rechargeable Zinc–Air Battery

Transforming discardable solid waste like polystyrene (PS) foams into commercially useful applications like sustainable and eco‐friendly energy materials has attracted considerable attention. Herein, expanded PS waste is subjected to simple reactions (cross‐linking and pyrolysis) to obtain a high‐performing electrocatalyst for the oxygen reduction reaction (ORR). The optimized catalyst polystyrene‐pyrrole (PSP‐800) demonstrates good electrocatalytic ORR activity toward rechargeable zinc–air battery due to its high surface area, copious amount of micropores/mesopores, high nitrogen content, and a trace amount of Fe doping. Accordingly, PSP‐800 delivers a high onset potential (0.99 V) and a half‐wave potential of 0.88 V versus a reversible hydrogen electrode. Moreover, the rechargeable zinc–air battery using PSP‐800 as an ORR catalyst demonstrates improved stability and high‐power density (116 mW cm−2) compared to the standard Pt/C catalyst.

Persulfate oxidation of tetracycline, antibiotic resistant bacteria, and resistance genes activated by Fe doped biochar catalysts: Synergy of radical and non-radical processes

To reduce the adverse effects of antibiotics and antibiotic resistance genes (ARGs) in the environment, this study employed iron-loaded biochar (Fe-LBH) as an activator in a persulfate (PDS) oxidation system to degrade tetracycline (TC), inactivate antibiotic resistant bacteria (ARB), and remove ARGs. TC was removed efficiently (more than 85%) in the Fe-LBH-PDS system within 30 min, which was higher than that in the pristine biochar-PDS system (15.5%). The Fe doping amount in biochar, PDS, and catalyst dose significantly affected TC degradation. Furthermore, the Fe-LBH-PDS system inactivated 60.4% of ARB (Pseudomonas aeruginosa HLS-6) within 60 min. The removal efficiencies of ARGs (sul1 and sul2) and intI1 were 0.05–0.60- and 1.54–2.74 log2-fold, respectively. Fe (II) and oxygen functional groups (e.g., -C-OH and -C = O) were verified as the reactive sites for PDS activation. In addition, according to the results of electron paramagnetic resonance (EPR) and radical quenching experiments, the radical pathway dominated by OH and the non-radical pathway dominated by singlet oxygen (1O2) play synergistic roles in the Fe-LBH-PDS oxidation process. These findings provide a possible application of Fe-LBH-PDS for TC degradation and hindering antibiotic resistance dissemination in wastewater treatment practice.

Effects of Fe doping on Martensitic Transformation and magnetic properties of Ni-Mn-Ti All-d-metal Heusler Alloy

<sec>Ni-Mn-Ti-based all-d-metal Heusler alloys have become a hot research topic in the field of metal functional materials due to their excellent mechanical properties and elastocaloric effect. However, the relatively large critical stress and transition hysteresis limit its practical applications. Some researchers have found that doping Fe in Ni-Mn-based alloys can not only reduce hysteresis, but also greatly improve the mechanical properties of alloys. Based on this, the effects of Fe doping on phase stability, martensitic transformation and magnetic properties of Ni<sub>50–<i>x</i></sub>Mn<sub>37.5</sub>Ti<sub>12.5</sub>Fe<sub><i>x</i></sub> (<i>x</i> = 3.125, 6.25, 9.375) Heusler alloys are systematically studied by first principles calculation. The corresponding magnetic states of the austenite and martensite of the alloy systems are determined according to the results of the formation energy. The variations of the lattice constants and the phase stability of the austenite and martensite with the increase of Fe content in the alloy systems are revealed, and the associated mechanism is elucidated. The atomic and total magnetic moments of the austenite and martensite in the Ni<sub>50–<i>x</i></sub>Mn<sub>37.5</sub>Ti<sub>12.5</sub>Fe<sub><i>x</i></sub> (<i>x</i> = 3.125, 6.25, 9.375) systems are calculated. Based on the results of electronic structure, the essential reasons for the magnetic state changes of the alloys are further explained.</sec><sec>In the Ni<sub>50–<i>x</i></sub>Mn<sub>37.5</sub>Ti<sub>12.5</sub>Fe<sub><i>x</i></sub> alloy system, the lattice constant of austenite decreases gradually with the increase of Fe doping amount. The stability of austenite phase and martensite phase decrease with the increase of Fe doping amount. Under the different compositions, the formation energy of martensite is always lower than that of austenite, indicating that the alloy can undergo martensite transformation. The energy difference Δ<i>E</i>, electron concentration <i>e</i>/<i>a</i> and density of electrons <i>n</i> of the alloy show a decreasing trend, indicating that the driving force of martensitic transformation decreases, and the corresponding martensitic transformation temperature decreases with the increase of Fe atom doping.</sec><sec>The austenite of the alloy is ferromagnetic and the martensite is antiferromagnetic. After the martensitic transformation, the distance between Mn-Mn atoms decreases, and the magnetic moments of Mn<sub>Mn</sub> and Mn<sub>Ti</sub> atoms are arranged in antiparallel manner, resulting in the total magnetic moments being almost zero. The magnetic properties of the two phases are little affected by the amount of Fe atom doping. The peak density of electronic states in the Fermi surface of martensite phase is lower than that of austenite phase, indicating that martensite phase has a more stable electronic structure than austenite phase. During the transition from austenite to martensite, there is a Jahn-Teller splitting effect at the peak of the down-spin density of states near the Fermi surface. The aim of this paper is to provide guidance for designing the composition design and optimizing the property of the Ni-Mn-Ti-Fe alloy.</sec>

Synchronously boosting microwave-absorbing and heat-conducting capabilities in CeO2/Ce(OH)3 core-shell nanorods/nanofibers via Fe-doping amount control.

To address the electromagnetic interference (EMI) and heat dissipation issues in electronics, we pioneered the synthesis of Fe-doped CeO2/Ce(OH)3 core-shell nanorods/nanofibers (CSNRs/NFs) through a simple one-pot hydrothermal reaction. The growth of core-shell nanofibers was driven by the minimal surface free energy and vacancy formation energy. By controlling the amount of Fe-doping, not simply Fe0 content, crystallite size, defects, impurities, and length/diameter ratios could be modulated, but the electric, magnetic, thermal, and microwave absorption performance. The efficient 3D network constructed by 1D nanofibers in a silicone matrix offered a continuous pathway for electrons/phonon relay transmission, endowing the composites with exceptional heating conductance (3.442 W m-1 K-1) at 20%Fe-doping. An ultrawide absorption band (9.26 GHz) with intense absorption (-42.33 dB) and small thickness (1.7 mm) was achieved at 10%Fe-doping due to excellent matching performance, strong attenuation ability, and large EM parameters. Overall, Fe-doped CeO2/Ce(OH)3 CSNFs are a promising material for next-generation electronics with effective heat dissipation and EM wave absorption due to their straightforward process, mass production, and outstanding comprehensive performance. Beyond providing a deeper insight into the accurate defect modulation in magnetic-dielectric-double-loss absorbents by doping, this paper proposes an electron/phonon relay transmission strategy to improve heat conductance.

Removal and recycling of selenite anions by iron-doped cobalt-based metal organic frameworks for oxygen evolution reaction

As the main form exists in selenium-containing wastewater, selenite (SeO32-) is often produced by human activities and is exceedingly difficult to be removed from wastewater. In this study, five iron-doped (Fe-doped) cobalt-based metal organic frameworks (Co/Fe-MOF) with different metal ratios were prepared to remove SeO32- anions. The prepared Co/Fe-MOF were confirmed by characterization and their adsorption properties experiments. They have excellent SeO32- removal performance at pH of 3–8 with a maximum adsorption capacity of 283.11 mg g−1 of Co-MOF. After uptaking SeO32- by Co/Fe-MOF, the used Co/Fe-MOF (U-Co/Fe) contains CoSeO4 and Fe2(SeO4)3 and can be used as electrocatalytic oxygen evolution catalysts. Their oxygen/selenium vacancies can reduce the overpotential of the oxygen evolution reaction (OER). In 1.0 M KOH, U-Co0.90Fe0.10 displayed the lowest overpotential 326 mV at 10 mA cm−2. This study reveals the mechanism and resource upgrading process of SeO32- removal by Co/Fe-MOF and demonstrates that a small amount of Fe doping could improve the performance of OER.

Preparation of Iron‐Doped Carbon Dots and Their Application in Photocatalytic Reduction of Carbon Dioxide

AbstractPhotocatalytic carbon dioxide (CO2) reduction technology is considered a promising approach to alleviate greenhouse gas emissions in the earth's atmosphere. Carbon dots (CDs), which possess good optical properties, are of keen interest in the field of photocatalysis. Iron (Fe), a transition metal element with vacant 3d orbital that contributes to the electron‐transfer process, is a promising metal dopant for CDs that allows for the preparation of multifunctional CDs. Fe‐doped carbon dots (Fe−CDs) were synthesized using ethylenediamine tetraacetic acid disodium (EDTA‐2Na) and ferric chloride (FeCl3 ⋅ 6H2O) through a simple one‐step hydrothermal method. The chemical structure of the obtained Fe−CDs was studied, and their activity for the photocatalytic reduction of CO2was tested. The results show that Fe doping amount of 13.0 wt.% is the most favorable for the photocatalytic reaction. The maximum photocatalytic reduction of CO2to methanol reaches 654.28 μmol ⋅ g−1 ⋅ h−1within 6 h, which is about 2.6 times of the methanol yield of CDs, which is attributed to high electron transfer rate of Fe dopant.

Ultra-sensitive electroanalysis of toxic 2,4-DNT on o-CoxFe1-xSe2 solid solution: Fe-doping-induced c-CoSe2 phase transition to form electron-rich active sites

How to achieve the sensitive electroanalysis of organics pollution in water environment is vital significance, but it is limited by their redox inert and the ambiguous detection mechanism. Herein, Fe-doping-induced structural phase transition engineering is designed to make the cubic (c-) CoSe2 to orthorhombic (o-) CoSe2, accompanying with the formation of o-CoxFe1-xSe2 solid solution. By controlling the Fe doping amount, the fully orthogonalized C1F1 (the mole ratio of Co/Fe is 1:1) electrode acquires a high sensitivity of 0.293 μA μM−1 toward 2,4-Dinitrotoluene (2,4-DNT) detection. Besides, C1F1 exhibits excellent stability, reproducibility and practicality for 2,4-DNT detection. Combined with experimental studies and theoretical calculations, it is shown that during the phase transition, electrons are transferred from Co to Fe, forming electron-rich Fe active sites. The Fe sites can match well with free 2,4-DNT molecules and then accelerate the reduction process of 2,4-DNT. A series of experiments including DFT and electrochemistry demonstrate that the doping-induced structural phase transition strategy can improve the adsorption performance of the material and also enhance the catalytic ability, thereby enhancing the electrochemical sensitivity. The co-engineering of morphology and phase transition of metal selenides by doping will provide inspiration for the design of sensitive sensing interfaces for organic pollutants.

Enriched photocatalysis-Fenton synergistic degradation of organic pollutants and coking wastewater via surface oxygen vacancies over Fe-BiOBr composites

Fe-doped three-dimensional flower-like structures BiOBr (Fe-BiOBr) with rich surface oxygen vacancies (OVs) were prepared by a simple microwave method, and the Fe-BiOBr composites completely degraded phenol solution (20 ppm) after 60 min of visible light irradiation in the presence of H2O2. The degradation activity was 12.32 and 1.46 times that of photocatalytic and Fenton reactions, respectively. The catalytic degradation activity was still as high as 90% after five recycles and had good structural stability. Meanwhile, the Fe-BiOBr composites also exhibited good removal efficiency for other phenolics and coking wastewater, and the chemical oxygen demand (COD) and total organic carbon (TOC) removal efficiency of coking wastewater were 63.6% and 53.8%, respectively. Both theoretical calculations and experimental results showed that oxygen vacancies could effectively promote the photocatalytic Fenton synergistic degradation activity, which not only improved the separation efficiency of photogenerated carriers, promoted the transformation of the Fe ion valence state and realized the cycle of the Fenton reaction but also acted as the adsorption and activation site of H2O2 to produce hydroxyl radicals, the most important active species in the synergistic degradation system, which was confirmed by quenching experiments and EPR results. The effects of the Fe doping amount, H2O2 concentration and other factors on the degradation activity were investigated. Based on the results of the experiment and theoretical calculations, the degradation mechanism of the surface oxygen vacancies enhancing the photocatalysis-Fenton degradation activity was proposed.

Superior indicative and regulative function of Fe doping amount for MnO2 catalyst with an oxygen vacancy in NH3-SCR reaction: A DFT + U study

MnO2 was a promising catalyst in selective catalytic reduction (SCR) reaction at low temperature. In this research, density functional theory calculations were carried out to evaluate the NH3-SCR performance of MnO2 catalyst with an oxygen vacancy (MnO2-x). Results demonstrated that MnO2-x became the thermodynamically most preferred structure after Fe doping, and its structure was kept stable as the doping amount increased. The adsorption behaviors of gaseous molecules on the MnO2-x showed that NH3 and H2O preferred to be adsorbed on the Mn Lewis acid sites, while NO and SO2 preferred O sites. Good SO2-tolerance also exhibited in MnO2-x for its enhanced acidity after Fe doping. Moreover, outstanding linear relationships were emerged in doping ratio with oxygen vacancy formation energy and adsorption energy, suggesting its important role in the balance of redox and acidity properties. Thermodynamic calculation results confirmed the inhibitory effect of temperature on adsorption and found the implication of doping amount to H2O-tolerance. Overall, Fe2-MnO2-x catalyst performed best in our work. Strong indication of doping amount was found by further calculations of four physical quantities. In general, doping amount was an outstanding indicator to reflect the characteristics of catalysts, and can be employed in the future directional catalyst designs.

Electrooxidation of ammonia on A-site deficient perovskite oxide La0.9Ni0.6Cu0.35Fe0.05O3-δ for wastewater treatment

Wastewater can contain high amounts of ammonia which can pose as a great safety threat if released into natural waters. The electrochemical oxidation of ammonia offers a viable strategy to remove high concentrations and provides an attractive method for wastewater treatment. However, finding a highly efficient and low-cost catalyst is imperative for overcoming the sluggish nature of ammonia oxidation reaction. Herein, a modified A- and B-site perovskite is proposed as a catalyst for the oxidation of ammonia, making it suitable as an anode in an ammonia electrolyser. A series of La1-yNi0.6Cu0.4-xFexO3-δ (x = 0, 0.05 and 0.10; y = 0, 0.05 and 0.10) perovskite materials were synthesised by a conventional sol–gel method. Amongst those tested oxides, La0.9Ni0.6Cu0.35Fe0.05O3-δ was found to have superior activity towards the electrooxidation of ammonia due to an optimised amount of Fe doping and the presence of oxygen vacancies introduced by an A-site deficiency. Subsequently, La0.9Ni0.6Cu0.35Fe0.05O3-δ was employed as an anode in an ammonia electrolyser where the ammonia removal efficiency reached 95.4 % in simulated wastewater after 80 hr and a substantial reduction in real wastewater was also observed. These results demonstrate that the A-site deficient perovskite materials are a viable electrode for the removal of ammonia in a practical energy setting and paves way for future applications.

Kinetic study on the effect of iron on the grain growth of rutile-type TiO2 under in situ conditions

There have been many studies on the growth kinetics of titanium dioxide and doped titanium dioxide. However, most calculated the grain size after isothermal treatment and cooling to room temperature; thus, the real grain size of titanium dioxide at the real-time temperature during heat treatment could not be obtained. This study thus aimed to obtain accurate grain information during the heat treatment process. In this study, titanium oxysulfate (TiOSO4) and ferric chloride (FeCl3·6H2O) were used to hydrolyze and precipitate TiO2 precursors containing impurity iron. Then, the sample was subjected to high-temperature in situ x-ray diffraction. Using the Williamson–Hall mapping method to process the x-ray diffraction information, the grain size could be used to characterize changes in the grain size, and the change law of TiO2 during the heat treatment process was studied. Furthermore, the effect of Fe doping on the growth of TiO2 crystals was examined through the crystal growth kinetics. The results revealed that when the Fe doping amount reached a certain level, it affected the growth mechanism of the rutile type titanium dioxide grains, thereby causing a change in the growth order. Specifically, an increase in the Fe doping amount increased the growth activation energy; that is, it inhibited the growth of rutile-type titanium dioxide grains.

Doping Ce(OH)CO3 laminated dendrites with Fe, Co and Ni for defect steered wide-frequency microwave absorption

Defect engineering is a key strategy to modulate the properties of dielectric-dominated metal oxides. To ascertain the correlation between lattice/oxygen vacancy defects and microwave absorption properties (MWAPs), we herein developed a one-pot hydrothermal reaction to controllably synthesize Fe/Co/Ni-doped CeOHCO3 laminated dendrites as defects steered wide-frequency absorbers for the first time. The crucial effect of dopants on their MWAPs has been investigated based on the morphology, composition, and defect features. Fe/Co/Ni doping restricts the growth of CeOHCO3 nanosheets along the [1100], [0110], and [1010] directions, causing the morphology evolution from laminated dendrites to spherical aggregates. Meanwhile, the increase of lattice/oxygen vacancy defects with Fe doping amount causes a linear increase in Ms and conductivity. Such changes improve the impedance matching and attenuation ability of CeOHCO3 owing to the enhanced permeability and multiple polarizations. The optimal comprehensive MWAPs are achieved by 10%Fe-doped CeOHCO3 laminated dendrites with an RLmax of −47.22 dB at 2.4 GHz and an EABmax/d of 3.47 GHz/mm, much superior to those of most other absorbers. Our work not only enlightens the precise defect modulation in dielectric-type absorbers via metal atomic doping but creates a new research methodology to develop advanced microwave absorbents.

Unveiling structure–property relationships of Fe-promoted Rh-Mn/UiO-66-drived catalysts for C2 oxygenates formation from syngas

The effect of iron promoter on the catalytic performance of Rh-Mn/UiO-66-drived catalyst was studied by syngas conversion. The catalysts were completely characterized by means of X-ray diffraction (XRD), N2 sorption, transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), diffuse reflectance infrared Fourier transform spectra (DRIFTS), and temperature-programmed surface reaction (TPSR). When the amount of Fe doping reached 0.3 wt%, the catalyst has the excellent catalytic activity with the highest C2+ oxygenates yield of 300.1 g/(kg·h). The results indicated that the appropriate addition of iron can enhance the Rh-Fe interaction, which promote the reduction of Rh active sites. The Rh0-rich state would be observed on the catalysts doped by the appropriate amount of Fe, resulting in the enhancement of CO dissociation ability and strength of the Rh-CO bond, which should be responsible for the higher conversion rate and selectivity of C2+ oxygenates.

Preparation of phosphorylated iron-doped ZIF-8 and their adsorption application for U(VI)

In this study, a 10%Fe-ZIF-8-300-PO4 adsorbent was synthesized and its adsorption performance for U(VI) was investigated comprehensively. It was found that after a series of operations such as Fe doping, thermal activation and phosphorylation, the adsorption performance for U(VI) can be significantly improved on the basis of maintaining the skeleton characteristics of ZIF-8. The results showed that the optimal Fe-doping amount and thermal activation temperature was 10% and 300°C, respectively. The adsorption of U(VI) on 10%Fe-ZIF-8-300-PO4 reached equilibrium within 60 ​min, and conformed to pseudo-second-order kinetic equation. Furthermore, a maximum saturated adsorption capacity of 691.83 ​mg/g was achieved. The above results demonstrated that 10%Fe-ZIF-8-300-PO4 may be used to efficiently remove U(VI) from uranium-containing radioactive waste water.

Low-Temperature Hydrogenation of Toluene Using an Iron-Promoted Molybdenum Carbide Catalyst

As an alternative to noble metal hydrogenation catalysts, pure molybdenum carbide displays unsatisfactory catalytic activity for arene hydrogenation. Precious metals such as palladium, platinum, and gold are widely used as additives to enhance the catalytic activities of molybdenum carbide, which severely limits its potential applications in industry. In this paper, iron-promoted molybdenum carbide was prepared and characterized by various techniques, including in situ XRD, synchrotron-based XPS and TEM. while the influence of Fe addition on catalytic performance for toluene hydrogenation was also studied. The experimental data disclose that a small amount of Fe doping strongly enhances catalytic stability in toluene hydrogenation, but the catalytic performance drops rapidly with higher loading amounts of Fe.

Praperation of magnetic Fe,N co-doped nano-sized graphitized carbon aerogel with hierarchical porous structure and its electrochemical and adsorption performance

<p indent=0mm>Nano-sized carbon materials have received intensive preoccupation owing to their extraordinary properties such as high specific surface area, abundant porous structure, and excellent electronic properties. Doping non-metallic element N can effectively modulate the electronic properties of graphene, and doping metallic element Fe can further improve their catalytic activity. To date, applications of Fe-N/C materials are mostly concentrated in supercapacitors, electrochemical double layer electrode materials or adsorption. In this communication, we present a novel route for fabricating Fe,N co-doped nano-sized graphitized carbon materials (FeNC aerogels) by a chelate-carbonization-activation process using chitosan-Fe³⁺ chelate and KOH as precursor and activator respectively. Chitosan-Fe³⁺ chelate aerogel was first formed via sol-gel process, and Fe³⁺ was chelated by chitosan and evenly distributed in 3D networks of aerogel. Then in a nitrogen atmosphere, Chitosan-Fe³⁺ chelate aerogel was pyrolyzed at elevated temperature, and Fe³⁺ was reduced to Fe nanoparticles under the control of chitosan molecular in this carbonization process. At the last stage of KOH activation process, most of the amorphous carbon was etched, and abundant nanoscale pores appeared. Upon mild heating at 70°C in air, core@shell Fe@Fe₃O₄ nanoparticles were formed due to the reaction of Fe nanoparticles inside the Fe-N/C aerogels with oxygen in air. The morphology, structure, and properties of the obtained FeNC aerogels were characterized using field emission scanning electron microscope (FESEM), high-resolution transmission electron microscope (HRTEM), element mapping, Raman spectra, X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), and vibrating-sample-magnetometer (VSM). FeNC aerogels were confirmed to be Fe,N-contained carbon aerogels with 3D hierarchical porous scaffold including macropores, micropores and mesopores, displayed low density and good magnetic response. The as-prepared FeNC(1-100)-K800 showed extremely large specific surface area <sc>(3103 m²/g),</sc> low density <sc>(27 mg/cm³),</sc> and high nitrogen content (4%). The magnetic response ability of FeNC aerogels increased with the increase of Fe content, and Fe was doped as Fe@Fe₃O₄ and Fe-N. FeNC aerogels exhibited good electrocatalytic oxidation-reduction activity, which increased with the increase of Fe doping amount, graphitization degree, and specific surface area. The obtained FeNC(1-20)-K800 with the highest Fe doping amount showed the highest initial potential of <sc>0.98 V,</sc> half-wave potential of <sc>0.82 V</sc> in<sc>0.1 mol/L</sc> KOH electrolyte saturated with O₂, and the highest initial potential of <sc>0.92 V,</sc> half-wave potential of <sc>0.62 V</sc> in<sc>0.05 mol/L</sc> H₂SO₄ electrolyte, respectively. Meanwhile, FeNC aerogels showed good performance of the electric double layer capacity and good cycling stability, and the specific capacitance enhanced with the increase of specific surface area. The specific capacitance, energy density, and power density of FeNC(1-40)-K800 was <sc>253 F/g,</sc> 35.1 W h/kg, and <sc>249.7 W/kg</sc> respectively. And its specific capacitance retention rates were 92.9% and 88.6% respectively after 6000 times and 10000 times continuous charge-discharge cycles at a current density of <sc>10 A/g.</sc> Furthermore, The saturated adsorption capacities of four kinds of dyes: Methyl orange (anionic dye), Rhodamine B (neutral dye), crystal violet and malachite green (cationic dyes), on FeNC(1-20)-K800 all exceeded <sc>400 mg/g,</sc> and the saturated adsorption capacity of malachite green reached up to <sc>816 mg/g.</sc> FeNC aerogel prepared here is a new type of carbon materials with application potential in the field of new energy and environmental remediation. The novel aerogel preparation process we preposed is suitable for large-scale industrial preparation without environmental risks because complex nitrogen and iron treatment steps and expensive equipments are not needed.

Fe-doping effect on magnetic properties of La2CoMnO6 ceramics prepared by Plasma Activated Sintering

Fe doped La2CoMnO6 perovskite La2Co(1-x)FexMnO6 (abbreviated as LCFxMO, x = 0.1˜0.4) ceramics exhibiting P21/n phase and dense structure with micron grains resulted from the lower sintering temperature of 930 °C were fabricated by plasma activated sintering. The Co2+/Mn4+ concentration in LCFxMO ceramics gradually increased with the increase of Fe doping, then decreased due to excessive doping, reflecting the change of order degree of B-site cations. The Co2+/Mn4+ concentration reached the highest value in LCF0.2MO, which proved the ascendant B-site cations ordering degree of LCF0.2MO. Moreover, the smaller grains resulted from rapid sintering period was also one of another cause of high order degree. It was found that the saturation magnetization was greatly enhanced by a small amount of Fe doping. Comparing to other Fe doped content of LCFxMO ceramics, the LCF0.2MO ceramic also had the largest saturation magnetization (57.05 emu/g).

In situ synthesis of Fe-doped CrOOH nanosheets for efficient electrocatalytic water oxidation

The oxygen evolution reaction (OER) is a process in electrochemical water splitting with sluggish kinetics that needs efficient non-noble-metal electrocatalysts. There have been few studies of CrOOH electrocatalysts for water oxidation due to their low performance. Herein, in situ synthesized Fe-doped CrOOH nanosheets on Ni foam (Fe-CrOOH/NF) were designed as electrocatalysts and performance in the OER was obviously improved. The effect of the amount of Fe doping was also investigated. Experiments revealed that the best performance of Fe-CrOOH/NF requires low overpotentials of 259 mV to reach 20 mA cm−2 together with a turnover frequency of 0.245 s−1 in 1.0 M KOH, which may suggest a new direction for the development of Fe-doped OER electrocatalysts.