Fe Co-doping Research Articles

Role of oxygen in enhancing magnetism of Fe-doped MoSi2N4 monolayer from first-principles study

MoSi2N4 is a new type of two-dimensional layered material, which is semiconducting with novel valley-physics properties and excellent stability, suggesting its great applications in the field of valleytronics and spintronics. In present work, the spin-polarized electronic structure and magnetic properties of different doping models of MoSi2N4 are investigated based on first principles. The results show that Fe doping presents a semi-metallic band structure, inducing a total magnetic moment of 4.01 μB. For Fe + O co-doping configuration, further introduction of the O atom increases the total magnetic moment to 5.0 μB. The magnetic moments mainly originate from the coupling of Fe-3d and O-2p and Mo-4d and O-2p. Then, the calculations show that the stability of Fe + O + Fe co-doping configuration is enhanced and exhibits antiferromagnetic order with a total magnetic moment of about 0.98 μB. Due to the antiferromagnetic interaction, the magnetic moment is mainly derived from the hybridization of Mo-4d and O-2p states, and a transition from semi-metallic to metallic band structure is observed.

Fe-NiO/MoO2 and in-situ reconstructed Fe, Mo-NiOOH with enhanced negatively charges of oxygen atoms on the surface for salinity tolerance seawater splitting

Seawater electrolysis is a promising technique for H2 production on a large scale. However, the electrocatalytic activity and stability will be deteriorated as the increase of salt concentrations which happened in the seawater splitting. Herein, through the electrodeposition and rapid Joule heating method, the Fe-NiO/MoO2 heterostructure is designed as a highly active bifunctional electrocatalyst. During the OER possess, Fe-NiO/MoO2 is reconstructed to the Fe, Mo-NiOOH with Fe and Mo co-doping. Based on the theoretical analysis, more electrons were transferred to the O atoms on the surface of Fe, Mo-NiOOH, thereby forming a more negatively charged surface. Moreover, that surface is found to repel Cl− ions while enriching H2O molecules to form a thin water layer on Fe, Mo-NiOOH surface based on molecule dynamics (MD) simulation, thereby improving the anti-corrosion capacity of Fe, Mo-NiOOH. The reconstructed Fe, Mo-NiOOH achieved an overpotential of 399 mV at 1000 mA cm−2 in alkaline seawater, and the increase of overpotential for Fe, Mo-NiOOH was about 0.02 V at 500 mA cm−2 from 0 M to 3 M NaCl in 1 M KOH electrolyte. For the HER, Fe-NiO/MoO2 achieved an overpotential of 169 mV and 417 mV at 100 and 1000 mA cm−2 in alkaline seawater, respectively, and the increase of overpotential for Fe-NiO/MoO2 was about 0 mV at 500 mA cm−2 from 0 M to 3 M NaCl in 1 M KOH electrolyte. This work sheds fresh light into the development of efficient electrocatalysts for salinity tolerance seawater splitting.

Modulation of electronic structure of Ni3S2 via Fe and Mo co-doping to enhance the bifunctional electrocatalytic activities for HER and OER

Heazlewoodite nickel sulfide (Ni3S2) is advocated as a promising nonnoble catalyst for electrochemical water splitting because of its unique structure configuration and high conductivity. However, the low active sites and strong sulfur–hydrogen bonds (S–Hads) formed on Ni3S2 surface greatly inhibit the desorption of Hads and reduce the hydrogen and oxygen evolution reaction (HER and OER) activity. Doping is a valid strategy to stimulate the intrinsic catalytic activity of pristine Ni3S2 via modifying the active site. Herein, the Ni foam supported Fe and Mo co-doped Ni3S2 electrocatalysts (Fe-MoS2/Ni3S2@NF) have been constructed using Keplerate polyoxomolybdate {Mo72F30} as precursor through a facile hydrothermal process. Experimental results certificate that Fe and Mo co-doping can effectively tune the local electronic structure, facilitate the interfacial electron transfer, and improve the intrinsic activity. Consequently, the Fe-MoS2/Ni3S2@NF display more excellent HER and OER activity than MoS2/Ni3S2@NF and bare Ni3S2@NF by delivering the 10 and 50 mA cm−2 current densities at ultra-low overpotentials of 74/175 and 80/160 mV for HER and OER. Moreover, when coupled in an alkaline electrolyzer, Fe-MoS2/Ni3S2@NF approached the current of 10 mA cm−2 under a cell voltage of 1.60 V and exhibit excellent stability. The strategy to realize tunable catalytic behaviors via foreign metal doping provides a new avenue to optimize the water splitting catalysts.

Selective Lattice Doping Enables a Low-Cost, High-Capacity and Long-Lasting Potassium Layered Oxide Cathode for Potassium and Sodium Storage.

Layered transition metal oxides are highly promising host materials for K ions, owing to their high theoretical capacities and appropriate operational potentials. To address the intrinsic issues of KxMnO2 cathodes and optimize their electrochemical properties, a novel P3-type oxide doped with carefully chosen cost-effective, electrochemically active and multi-functional elements is proposed, namely K0.57Cu0.1Fe0.1Mn0.8O2. Compared to the pristine K0.56MnO2, its reversible specific is increased from 104 to 135 mAh g-1. In addition, the Cu and Fe co-doping triples the capacity under high current densities, and contributes to long-term stability over 500 cycles with a capacity retention of 68 %. Such endeavor holds the potential to make potassium-ion batteries particularly competitive for application in sustainable, low-cost, and large-scale energy storage devices. In addition, the cathode is also extended for sodium storage. Facilitated by the interlayer K ions that protect the layered structure from collapsing and expand the diffusion pathway for sodium ions, the cathode shows a high reversible capacity of 144 mAh g-1, fast kinetics and a long lifespan over 1000 cycles. The findings offer a novel pathway for the development of high-performance and cost-effective sodium-ion batteries.

Synthesis, characterization, and dielectricity performance of bulk pristine Fe3+ and Li+ Co-substituted wurtzite ZnO

High dielectric constant materials are of technological importance as they lead to the miniaturization of electronic devices. The permittivity of a material determines the relative speed that an electrical signal can travel in that material. The dielectric properties of pure ZnO are developed due to the defects of zinc excess at the interstitial position and the lack of oxidation. Fe and Li co-doping in ZnO are envisaged here to develop high dielectric materials by converting the material into a p-type semiconductor without creating stoichiometric oxygen defects in the lattice and making it robust against the oxidizing atmosphere. The formation of single-phase Fe and Fe/Li co-doped wurtzite ZnO samples is confirmed by X-ray diffraction analysis. The Fe and Fe/Li doping depresses the concentration of the intrinsic donor and impedes the conduction mechanism resulting in the highest dielectric constant (ɛr′) equivalent to 612 and 90,000 are found for bulk pristine Zn0.9Fe0.1O and Zn0.8Li0.1Fe0.1O at 400oC with 1000 ​Hz applied frequency. Also with an increase in frequency, the dielectric constant and dielectric loss are found to decrease. This behavior is attributed to different hopping mechanisms and defects formed during synthesis.

Effect of Fe and Zn co-doping on LiCoPO4 cathode materials for High-Voltage Lithium-Ion batteries

Lithium cobalt phosphate (LiCoPO4) has great potential to be developed as a cathode material for lithium-ion batteries (LIBs) due to its structural stability and higher voltage platform with a high theoretical energy density. However, the relatively low diffusion of lithium ions still needs to be improved. In this work, Fe and Zn co-doped LiCoPO4: LiCo0.9-xFe0.1ZnxPO4/C is utilized to enhance the battery performance of LiCoPO4. The electrochemical properties of LiCo0.85Fe0.1Zn0.05PO4/C demonstrated an initial capacity of 118 mAh/g, with 93.4 % capacity retention at 1C after 100 cycles, and a good capacity of 87 mAh/g remained under a high current density of 10C. In addition, the diffusion rate of Li ions was investigated, proving the improvement of the materials with doping. The impedance results also showed a smaller resistance of the doped materials. Furthermore, operando X-ray diffraction displayed a good reversibility of the structural transformation, corresponding to cycling stability. This work provided studies of both the electrochemical properties and structural transformation of Fe and Zn co-doped LiCoPO4, which showed that 10 % Fe and 5 % Zn co-doping enhanced the electrochemical performance of LiCoPO4 as a cathode material in LIBs.

Invigorating active sites for amorphous/crystalline heterophased co-based oxyhydroxide/tungstate toward enhanced electrocatalytic oxygen evolution: Trimetallic codoping-achieved synergistic regulation

Designing high-efficiency multimetal-based catalysts for oxygen evolution reaction at low overpotential is a grand challenge in alkaline water splitting due to the elusive synergistic effect between metal atoms. Blind pursuit of polymetallic miscibility cannot linearly enhance catalytic activity; instead, it incurs increased costs. Herein, we reported a facile trimetallic (Cu, Fe and La) codoping approach to tailor the electronic structure of Co-based oxyhydroxide/tungstate for boosting OER reaction. It was found that a better synergistic effect with Co can be exhibited only when Cu, Fe and La were coexisted in the catalyst. By virtue of this, the catalyst developed numerous oxygen vacancies, enhancing favorability for OER reaction and demonstrating high intrinsic activity. Systematic experiments additionally verified its improved reaction kinetics and optimized adsorption to intermediates. Ultimately, the prepared CoCuFeLa significantly reduced overpotential, decreasing by a minimum of 50 mV compared to monometallic doping. The alkaline electrolyzer based on the CoCuFeLa anode exhibited a low cell voltage of 1.53 V for water splitting. Remarkably, it experienced a substantial attenuation of 3.54 % after 150 h of continuous operation, attributing to the changes in the surface structure of the catalyst. This work provides a viable pathway for improving catalytic activity through multimetallic codoping, further promoting the design of more valuable multimetallic catalysts for hydrogen market.

Enhanced electrical and energy storage performances of Fe, Sb co-doped BNBCTS ceramics synthesized via the solid-state combustion technique

In this study BNBCTS ceramics were co-doped with Fe and Sb to form (Bi0.5Na0.5)0.93(Ba0.945Ca0.055)0.07(Ti(0.9946-x)Sn0.0054)(Fe0.5Sb0.5)xO3 ceramics (denoted as BNBCTS-xFS) with various x content and were prepared via the solid-state combustion technique to enhance the electrical and energy storage performance. The effect of co-doping Fe and Sb on the phase formation, defect dipole, microstructure, electrical and energy storage properties of BNBCTS-xFS ceramics was studied. When x content increased from 0.0 to 0.030, the amount of the rhombohedral (R) phase decreased from 51 to 24 % while the tetragonal (T) phase increased from 49 to 76 %. The increased Fe and Sb content increased the defect dipole of singly/doubly charged oxygen-vacancies (VO∙/ VO∙∙) and caused more Ti4+ to transition to Ti3+, which caused the transition temperature of the ferroelectric phase to relaxor state (TF-R) in the ceramics to drop to below room temperature and it exhibited relaxor characteristics at room temperature. The ceramic with an x content of 0.010 had the largest grain size (3.06 μm), excellence ferroelectric properties (Pr ∼31.04 μC/cm2, Pm ∼38.98 μC/cm2 and Ec ∼18.28 kV/cm), the largest electro strain (∼0.175 %) and a large d33* of 350 pm/V. Moreover, when x = 0.020, the ergodic relaxor ceramic showed the smallest grain size (1.03 μm), the lowest remanant polarization (Pr) of 4.52 μC/cm2 and the lowest coercive field (Ec) of 8.37 kV/cm, at an electric field of 60 kV/cm. More importantly, energy storage properties at the electric breakdown strength (Eb = 120 kV/cm) of the ceramics with an x content of 0.020 exhibited a recoverable energy storage density (Wrec) of 1.81 J/cm3, a total energy storage density (Wtotal) of 2.95 J/cm3 and an efficiency (η) of 61.30%, with excellent thermal (∼25–150 °C) and frequency stability (∼1–100 Hz). This study provides new insights into the modulation of BNBCTS ceramics with Fe and Sb co-doping, which could effectively improve the electrical properties and energy storage properties of BNBCTS-xFS ceramics.

Impact of morphology and oxygen vacancy content in Ni, Fe co-doped ceria for efficient electrocatalyst based water splitting.

Designing a highly efficient, low-cost, sustainable electrocatalyst for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) through water splitting is a current challenge for renewable energy technologies. This work presents a modified sol-gel route to prepare metal-ion(s) doped cerium oxide nanostructures as an efficient electrocatalyst for overall water splitting. Nickle (Ni) and iron (Fe) co-doping impacts the morphology in cerium oxide resulting in 5 nm nanoparticles with a mesoporous-like microstructure. The high level 20 mol% (1 : 1 ratio) of Ni + Fe bimetal-ion(s) doped CeO2 shows excellent HER and OER activities compared to the monodoped Fe/Ni and pristine CeO2. The co-doped catalysts required a low overpotential of 104 mV and 380 mV for HER and OER, respectively, in 1 M KOH, at a current density of 10 mA cm-2. The Tafel slopes of 95 mV dec-1 and 65 mV dec-1 were measured for HER and OER with the same representative samples which demonstrated excellent stability even after continuous operation for 20 hours in the alkaline medium. The unique morphology, enhanced oxygen vacancy (Ov) content and the synergistic effects of dopants in CeO2 play essential roles in enhancing the activities of Ni + Fe doped samples.

Hole-states in Li doped NiO: doping dependence of Zhang-Rice spectral weight.

We report on structural evolution and a dynamical transfer of spectral weight as observed in O K-edge X-ray absorption (XA) spectra upon hole doping in LixNi1-xO (0 ≤ x ≤ 0.24). We find that the unit cell of doped NiO evolves in a specific way up to an intermediate doping level (x = 0.12) and then follows a different trend. A double peak structure (one is localized and the other is more delocalized) of low energy spectral weight (LESW) at the O K-edge is identified and quantified. Normalized LESW is found to increase linearly with an effective doping concentration (∼x/(1 - 2x)) with a change in slope at x = 0.12, which is correlated to the observed structural evolution. Doping dependence of Ni L3-edge XA spectral shape closely follows the localized peak of LESW at the O K-edge. Our observations strongly support the Zhang-Rice (ZR) picture, confirming that doped holes in NiO are of primarily ZR character. Furthermore, we find that Fe co-doping destroys the ZR spectral weight and recovers the spectral shapes to that of NiO.

Sustainable conversion of agricultural biomass waste into electrode materials with enhanced energy density for aqueous zinc-ion hybrid capacitors

Herein, we demonstrate the facile, economic and highly scalable conversion of (N, O and Fe)-self-doped heteroatom Solanum melongena (SM) biomass into highly electro-active carbon material for symmetric supercapacitor and zinc-ion hybrid capacitor (ZIHC) applications. The SM is ubiquous agri-bio-waste that inherently possess electro-active constituents and upon conversion resulted in high surface area, self-doped heteroatoms (N, O and Fe) through one step pyrolysis. A synergetic combination of N, O and Fe co-doping and relatively high-surface-area features that offers widespread interfacial active sites for charge storage and fast kinetics of electrochemical reactions in both supercapacitor and battery-type capacitor to maximize energy and power output. The symmetric supercapacitor is fabricated using 6 M KOH, delivering high specific capacitance of 154.64 F/g at 0.1 A/g current density. Long cycling performance of device exhibits 99 % retention over 50,000 charge and discharge cycles at 10 A/g. While SM carbon as the cathode in zinc ion hybrid capacitor (ZIHC) endows excellent Zn2+ ion storage capacity with 2 M ZnSO4·7H2O as electrolyte. The ZIHC delivered an excellent specific capacitance of 313.08 F/g, a substantial energy density output of 141.35 W h/kg and a power density of 6935.38 W/kg. In addition, ZIHC exhibited better cyclic stability with 1.92 % loss over 20,000 charge and discharge cycles at 4 A/g. The ZIHC device delivered excellent output in wearable devices and in lightning the LED (25.04 min). This study provides ubiquitous agri-waste-derived carbon that can be outstanding electrode material in energy storage devices owing to their hierarchal pore configuration, graphitization degree and self-doping of heteroatoms.

Flower-shaped 1 T/2H-phase molybdenum disulfide co-doped with nickel and iron grown on carbon cloth for enhanced water splitting

The development of an efficient, bifunctional, and affordable catalyst has emerged as a valuable approach for electrocatalysis, as it enhances the charge transfer capability and the number of active sites of the catalyst. Herein, we synthesized a flower-like structure of nickel and iron co-doped molybdenum disulfide on carbon cloth (Ni/Fe-MoS2/CC) using a facile hydrothermal method. The Ni/Fe-MoS2/CC sample exhibited remarkable activity towards the hydrogen evolution reaction, with low overpotentials of −116 mV and a Tafel slope of 43 mV/dec at −10 mA/cm2. It also showed excellent performance in the oxygen evolution reaction with an overpotential of 202 mV and a Tafel slope of 65 mV/dec to afford a current density of + 10 mA/cm2 along with high stability. This study illustrates the beneficial effect of Ni and Fe co-doping on the synthesized flower-shaped MoS2 with the formation of 1 T phase on MoS2/CC, demonstrating significant potential in the field of electrocatalysis.

First-principles prediction of enhanced photocatalytic activity in La-X (X = Sc, V, Cr, Mn, Fe, Co, Ni, or Cu) Co-doped SrTiO3

The influence of La-X (X = Sc, V, Cr, Mn, Fe, Co, Ni, or Cu) co-doping on the electronic structure and photocatalytic activity of SrTiO3 system was investigated using the open-source software package Quantum Espresso (QE) based on density functional theory. Defect formation energy calculations showed an energy advantage for co-doped systems under Ti-poor and O-rich conditions. The La-V, La-Cr, La-Mn, La-Fe, and La-Ni co-doped systems showed magnetic properties with corresponding total magnetization of 0.08 µB, 2.97 µB, 3.30 µB, 1.00 µB and 1.00 µB, respectively. The La-X (X = V, Cr, Mn, Fe, Ni, or Cu) co-doped system exhibits photoabsorption activity in the visible region as compared to the pure SrTiO3. The La-X (X = Cr, Fe, Ni, or Cu) co-doped SrTiO3 exhibits a long carrier lifetime, especially the La-Fe co-doped system with a high effective mass ratio of holes to electrons of 5.79. However, the redox potential of the water decomposition reaction of the La-Cu co-doped system is too large, making it unsuitable for water splitting. In summary, the La-X (X = Cr, Fe, or Ni) co-doped systems exhibited intermediate states in the band structure and density of states, which better meet the specific requirements for photocatalysis compared to systems without intermediate states, showing superior photocatalytic potential. The band edge alignment of the three co-doped systems with water redox potentials demonstrated good matching. These findings suggest that La-X (X = Cr, Fe, or Ni) co-doped SrTiO3 is a promising candidate material for solar-driven water splitting.

Manipulation of magnetocaloric and elastocaloric effects in Ni–Mn–In alloys by lattice volume and magnetic variation: Effect of Co and Fe co-doping

The effects of Co and Fe co-doping Ni–Mn–In alloy on the phase stability, lattice parameters, magnetic properties, and electronic structures are systematically investigated by using the first-principles calculations. Results indicate that Fe atoms replace the excess Mn2 atoms by direct and indirect coexistence (Fe→Mn2 and Fe→In→Mn2); Co substitutes the Ni atoms by direct substitution (Co→Ni) for the Ni–Mn–In alloy. The austenites all exhibit the ferromagnetic (FM) state for the studied compositions. The NM martensites are in the ferrimagnetic (FIM-1) state for the Ni2Mn1.5In0.5, Ni2Mn1.25In0.5Fe0.25, Ni1.75Mn1.5In0.5Co0.25, and Ni1.75Mn1.25In0.5Co0.25Fe0.25 alloys, while the other compositions are in the FM state. The phase stability of austenite and martensite decreases with increasing Co and Fe co-doping. A magnetic-structural coupling transition occurs at x < 0.25 and y < 0.25. The Ni1.91Mn1.5In0.5Co0.08 and Ni1.91Mn1.42In0.5Co0.08Fe0.08 alloys exhibit an A→6M→NM transformation, accompanied by a magnetic transition. When Co and Fe are co-doped, the hybridization strength between Co and Fe is greater than that between Co/Fe and Mn. The enhancement of magnetocaloric and elastocaloric effects is favored by larger magnetization difference (∆M) and lattice volume change (∆V/V0). Based on the calculated phase stability, magneto-structure coupling, ∆V/V0 and c/a ratio, one can predict that the Ni2-xMn1.5-yIn0.5CoxFey alloy with Co content 0 ≤ x ≤ 0.25 and Fe content 0 ≤ y ≤ 0.05 is predicted to have good magneto-controlled functional behavior.

Modulation of the electronic structure of Co2P by Mo, Fe co-doping for efficient urea electrolysis

Hydrogen production by urea splitting not only plays an energy-saving role in the production of hydrogen energy, but also can purify wastewater containing urea, which has great advantages compared with hydrogen production by water splitting. In this study, Mo, Fe co-doped bifunctional Co2P electrodes were prepared through hydrothermal and moderate-temperature phosphating methods. Under the synergistic effect of bimetallic cations, the electronic structure of Co2P is effectively modulated, thus showing excellent electrochemistry performance in urea splitting. In the electrolyte solution of 1 M KOH and 0.5 M urea, the potential of urea oxidation reaction (UOR) is 1.26V, 1.316 V and 1.336V for driving current density of 10, 50 and 100 mA cm−2, and the overpotential of hydrogen evolution reaction (HER) is 194 mV, 244 mV and 268 mV for driving current density of 10, 50 and 100 mA cm−2. The overall urea electrolysis only requires a voltage of 1.415 V and 1.686 V to drive a current density of 10 and 50 mA cm−2, which is one of the best catalytic activities reported to date. The experimental results show that the increased activity is assigned to the rapid charge transfer, the exposure of more active sites and the improved conductivity due to the doping of bimetallic ions. Density functional theory (DFT) demonstrates that the prepared Mo, Fe co-doped Co2P electrodes has the smallest Gibbs free energy for hydrogen adsorption compared with Fe co-doped Co2P electrodes. This work laid a new foundation for the synthesis of bimetallic cation-doped transition metal phosphide (TMP) for urea-assisted water splitting.

Non-radical dominated degradation of chloroquine phosphate via Fe-based O-doped polymeric carbon nitride activated peroxymonosulfate: Performance and mechanism

The utilization of peroxymonosulfate (PMS)-based advanced oxidation process as a proficient approach for treating wastewater has garnered significant attention. However, the activation of PMS and the degradation of contaminants are highly dependent on or severely limited by the design and structured active sites of catalysts. Herein, an Fe-based O-doped polymeric carbon nitride catalyst, namely Fe-ONLH, was synthesized to activate PMS for the efficient removal of model pollutant chloroquine phosphate (CQP) via a non-radical dominant pathway with singlet oxygen (1O2). The rapid degradation of CQP in the developed Fe-ONLH/PMS system was achieved by the optimum degradation conditions predicted by Response Surface Method (RSM) and the catalyst dosage was considered to have the highest relative importance among the variables. Particularly, the ability of Fe and oxygen co-dopants to generate non-radical active species is mainly attributed to the various active sites on Fe-ONLH (e.g., Fe-O, graphite N, CO and NC-N2), which also exhibited advantages in adaptability of wide pH range, catalyst reusability, stability in complicated ionic environmental or water matrixes. Besides, probable intermediates and decomposition pathways of CQP attacked by non-radicals and radicals were analyzed. The current study provides new insights of Fe-base heterogeneous catalysts for PMS activation and non-radical pathway degradation of pollutants during wastewater treatment.

Dielectric polarization in MgFe2O4 coating and bulk doping to enhance high-voltage cycling stability of Na2/3Ni1/3Mn2/3O2 cathode material

Charging P2-Na2/3Ni1/3Mn2/3O2 to 4.5 V for higher capacity is enticing. However, it leads to severe capacity fading, ascribing to the lattice oxygen evolution and the P2-O2 phase transformation. Here, the MgFe2O4 coating and Mg, Fe co-doping were constructed simultaneously by Mg, Fe surface treatment to suppress lattice oxygen evolution and P2-O2 phase transformation of P2-Na2/3Ni1/3Mn2/3O2 at deep charging. Through ex-situ X-ray diffraction (XRD) tests, we found that the Mg, Fe bulk co-doping could reduce the repulsion between transition metals and Na+/vacancies ordering, thus inhibiting the P2-O2 phase transition and significantly reducing the irreversible volume change of the material. Meanwhile, the internal electric field formed by the dielectric polarization of MgFe2O4 effectively inhibits the outward migration of oxidized Oα− (α < 2), thereby suppressing the lattice oxygen evolution at deep charging, confirmed by in situ Raman and ex situ XPS techniques. P2-NaNM@MF-3 shows enhanced high-voltage cycling performance with capacity retentions of 84.8% and 81.3% at 0.1 and 1 C after cycles. This work sheds light on regulating the surface chemistry for Na-layered oxide materials to enhance the high-voltage performance of Na-ion batteries.

Influence of Sm and Fe Co-doping on Structural and Electrical Features of Yttrium Chromite Nanoparticles

Influence of Sm and Fe Co-doping on Structural and Electrical Features of Yttrium Chromite Nanoparticles

Removal of Sulfide Ions from Kraft Washing Effluents by Photocatalysis with N and Fe Codoped Carbon Dots.

N and Fe codoped carbon dots (N,Fe-CDs) were fabricated from citric acid, L-glutamic acid and ferric chloride via a hydrothermal method for the photocatalytic removal of S2- from kraft washing effluents (KWE). The N,Fe-CDs were fluorescent nanoparticles (average size of 3.18 nm) and catalyzed the oxidation of S2- following a first-order kinetic model with an activation energy of 33.77 kJ/mol. The N,Fe-CDs tolerated elevated temperatures as high as 80 °C without catalyst deactivation. The N,Fe-CDs catalysts were reusable for at least four cycles, preserving over 90% of the activity. In the treatment of KWE from the kraft pulping of eucalyptus, the concentration of S2- was decreased by the N,Fe-CDs from 1.19 to 0.41 mmol/L in 6 h. Consequently, near complete remediation was obtained in 24 h. In addition, half of the chemical oxygen demand was removed after treatment with 500 mg/L of the N,Fe-CDs. In addition, the present photocatalyst was safe within a concentration of 200 mg/L, as indicated by the acetylcholinesterase inhibition test. Our findings may help develop a cleaner production process for kraft brownstock washing.

Effect of Sm and Fe co-doping on structural, dielectric and magnetic properties of YCrO3 perovskite

In this report, impact of co-doping of samarium (Sm3+) and iron (Fe3+) on structural, dielectric and magnetic properties of YCrO3 compound has been investigated. Here, YCrO3 and Y1-xSmxCr1-yFeyO3 (x = 0.3, y = 0.1) compounds are synthesized successfully through sol–gel auto combustion route. The synthesized samples are characterized through X-ray diffraction (XRD), surface electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), impedance analyzer and vibrating sample magnetometer (VSM) techniques. Rietveld refinement of XRD analysis reveals that both the compounds are crystallized in distorted orthorhombic structure belongs to Pnma space group. It is observed that with co-doping of both Sm3+ and Fe3+, lattice unit cell volume increases. SEM micrograph shows that the grains are slightly elongated as compared to the undoped sample. The temperature variation of real part of dielectric permittivity (εr) and tangent loss (tan δ) are analyzed over a frequency range 40 KHz − 500 KHz at a temperature range 300 K − 523 K. The temperature dependent dielectric permittivity reveals that both εr and tan δ decrease with co-doping. Moreover, both the compounds show relaxor like ferroelectric transition. Room temperature field dependent magnetization analysis shows that maximum magnetization value increases with co-doping. The result reveals that the enhanced properties with co-doping can be useful for practical device applications.