Fe Bond Research Articles

Enrichment of cobalt in the Xiarihamu Ni-Co sulfide deposit in the East Kunlun orogenic belt, Western China: Constraints from distribution of cobalt in sulfides and Fe and S isotopes of sulfides

The Xiarihamu Ni-Co sulfide deposit in the East Kunlun orogenic belt (EKOB), western China, is the largest magmatic Ni-Cu-(Co) sulfide deposit found in the orogenic belts worldwide. The geochemical behavior of Co during the evolution of sulfide melt is key to understand the enrichment process of Co in the Xiarihamu deposit, however remains unclear. In this study, the Co contents of sulfide inclusions enclosed within olivine and pyroxene and those of the sulfides interstitial to olivine and pyroxene in the Xiarihamu deposit were examinated by the Scanning Electron Microscopy (SEM) -Energy Dispersive Spectroscopy (EDS) and Electron Probe Microanalyzer (EPMA). The Fe and S isotopic compositions of the sulfides were measured in situ by LA-MC-ICPMS. The results show that Co contents increase from silicate to sulfide and arsenide minerals, and from chalcopyrite to pyrrhotite and pentlandite in the sulfides. High Co contents in pentlandite of pyroxenite (av. 2.79 %) and gabbro (av. 7.34 %) indicate that Co is enriched in the pentlandite of pyroxenite in different stage of magma. The pyrrhotite and pentlandite show positive correlation of Co with Fe and Ni, and suggested isomorphic substitution of Co for Fe and Ni. The δ56Fe values increase from pyrrhotite to pentlandite due to kinetic fractionation of Fe isotopes of Fe valent and bond length/strength, because pyrrhotite has longer bond and weaker bond strength of Fe-S than pentlandite, and display lighter Fe isotopic compositions. The δ56Fe values of pentlandite increase substantially from host peridotite to pyroxenite, which could be related to subsolidus fractional crystallization processes of monosulfide solid solution (MSS). The sulfide segregated and crystallized early from the MSS is richen in light Fe isotope. The sulfides in gabbro have high δ34S values, similar to δ34S of the sulfides in the country rocks of Proterozoic granitic gneiss, indicating a continuous addition of external sulfur into magma chamber. The δ34S and δ56Fe values of the sulfides approximately increase with increasing Co contents. Higher δ56Fe and δ34S values and Co contents of pentlandite in the pyroxenite suggest that the Co enrichment is mainly associated with sulfide saturation of magmas by crustal contamination.

Flexibility Tuning of Dual‐Metal S─Fe─Co─N5 Catalysts with O‐Axial Ligand Structure for Electrocatalytic Water Splitting

AbstractThe electrocatalytic performance of metal–nitrogen–carbon (M─N─C) single‐atom catalysts remains a significant challenge due to their rigid active center. Controllable tuning of the local microenvironment and electronic structure is critical for M─N─C single‐metal site catalysts in improving the electrochemical performance and exploring the reaction mechanism. Herein, Co─N4 is selected as a benchmark among various M─N─C catalysts based on theoretical prediction and experimental studies. A dual‐metal S─Fe─Co─N5 catalyst is constructed by embedding Fe and S into the structure of Co─N4 motifs. Theoretical analysis and in situ characterizations illustrate that the active sites will in situ combine an O‐axial ligand to form S─Fe─Co─N5─O structure during the oxygen evolution reaction (OER), which can reduce the reaction energy of O*→OOH*. The Ab Initio Molecular Dynamics simulations and deformation energy for H*/O* adsorption reveal that the Fe─Co and S─Fe bonds exhibit flexible characteristics compared to the Co/Fe─N bonds. This flexibility of S─Fe─Co─N5─O structure facilitates the OER performance by reducing the OOH*→O2, which is the OER rate‐determining step, resulting in superior performance. The optimized S─Fe─Co─N5─O catalyst exhibits excellent OER (260 mV@50 mA cm−2) and hydrogen evolution reaction (138 mV@10 mA cm−2) performance in alkaline electrolytes. The reported regulation strategy ameliorates the micro‐environment of Co─N4 with tunable flexibility, which helps allow a basic comprehension of the electrochemical reaction mechanism.

Carbon encapsulated FeS nanosheet-nanoribbon interwoven sandwich structure as efficient sodium-ion battery anodes

Carbon encapsulation and optimization of nanoparticle structure are key strategies in the development of battery electrode materials. Herein, we report a simple, one step chemical vapor deposition-like method to synthesize carbon encapsulated sandwich structured nanosheets/nanoribbons of ferrous sulphide (FeS@C NSRs) as a high performance sodium-ion battery anode material. The structurally advantageous FeS@C NSRs arises from heating Fe foam in the presence of a sulphur-containing resin, which supplies both the sulphur and carbon for the reaction. FeS@C NSRs maintains a high capacity of 582.8 mAh g−1 at 0.1 A g−1 for 120 cycles and a high rate capability of 270 mAh g−1 at 10 A g−1 for 2500 cycles. The impressive cycling performance results from fast electron and ion transfer with low structural strain on the bulk material. Furthermore, in situ Raman spectroscopy and XRD also reveal evidence that FeS@C NSRs cycles via a fully reversible conversion reaction pathway facilitated by the C–S–Fe bond. The efficient synthesis method could also be explored to produce other carbon coated transition metal sulphides for electrochemical applications.

Evolution of medium-range order and its correlation with magnetic nanodomains in Fe-Dy-B-Nb bulk metallic glasses

Fe-based metallic glasses are promising functional materials for advanced magnetism and sensor fields. Tailoring magnetic performance in amorphous materials requires a thorough knowledge of the correlation between structural disorder and magnetic order, which remains ambiguous. Two practical difficulties remain: the first is directly observing subtle magnetic structural changes on multiple scales, and the second is precisely regulating the various amorphous states. Here we propose a novel approach to tailor the amorphous structure through the liquid-liquid phase transition. In-situ synchrotron diffraction has unraveled a medium-range ordering process dominated by edge-sharing cluster connectivity during the liquid-liquid phase transition. Moreover, nanodomains with topological order have been found to exist in composition with liquid-liquid phase transition, manifesting as hexagonal patterns in small-angle neutron scattering profiles. The liquid-liquid phase transition can induce the nanodomains to be more locally ordered, generating stronger exchange interactions due to the reduced Fe–Fe bond length and the enhanced structural order, leading to the increment of saturation magnetization. Furthermore, the increased local heterogeneity at the medium-range scale enhances the magnetic anisotropy, promoting the permeability response under applied stress and leading to a better stress-impedance effect. These experimental results pave the way to tailor the magnetic structure and performance through the liquid-liquid phase transition.

First-principles calculation of bonding and hydrogen trapping mechanism of Fe3C/α-Fe interface

The Fe3C/α-Fe interface in pearlite is the main hydrogen trapping site. The first-principles calculation method based on density functional theory was employed to investigate the bonding and hydrogen trapping mechanism of the Fe3C/α-Fe interface with three different orientation relationships, specifically the Bagaryatsky orientation, Isaichev orientation, and Pitsch-Petch orientation. The results showed that by calculating the interface energy and separation work, the theoretical bonding strength and stability of the three interfaces presented the following order: Isaichev orientation > Pitsch-Petch orientation > Bagaryatsky orientation. Hydrogen segregation energy revealed that H atoms were more likely to be trapped at the Fe3C/α-Fe interface region and the hydrogen trap ability of three interfaces was in the following order: Isaichev orientation > Pitsch-Petch orientation > Bagaryatsky orientation. The maximum absolute value of segregation energy was found at the interface with Isaichev orientation, which was 0.38 eV. The differential charge density, density of states, and Mulliken bond population calculations revealed that the formation of the interface was related to the covalent bond between C atoms in cementite and Fe atoms in ferrite, and affected by the spatial distribution of C atoms. The C atoms also repelled the H atoms, so the strength of H–Fe bond was identified as the dominant factor of hydrogen trapping behavior. Overall, these insights can potentially aid in improving the design and performance of materials with pearlite structures.

Improved Access to ‘Butterfly’ Di‐Iron Dithiolates Fe2(μ‐SR)2(CO)6 and their Mono‐ and Bis(phosphine) Adducts

AbstractA series of Fe2(μ‐SR)2(CO)6 complexes {R=Me (1Me), Et (1Et), Pr (1Pr), iPr (1iPr), tBu (1tBu), PhCH2 (1Bn) and Ph (1Ph)} have been synthesised. Complexes 1Me, 1tBu, 1Bn and 1Ph were produced by addition of S2R2 to Fe3(CO)12, with all but 1tBu giving excellent yields. Two isomers of 1Me and 1Ph were isolated: the anti‐ and ‘open’ syn‐products. Complexes 1Et, 1Pr and 1iPr were synthesised by treatment of RSH with Fe3(CO)12; two isomers of each complex were isolated. Addition of one equivalent of PR’3 (R’=Me, Cy, Ph) yields the corresponding mono(phosphine) adducts, whilst use of two equivalents of the phosphine (under mild condition, reflux, or irradiation using a deep blue LED depending on SR group) affords the corresponding bis(phosphine) adducts in good to excellent yield. Treatment of 1Ph or 1Me with two equivalents of PMe3 gives the corresponding bis‐substituted phosphines when carried out in the absence of light but leads to oxidative cleavage to Fe(μ‐SPh)2(PMe3)2(CO)2 and Fe(μ‐SMe)2(PMe3)2(CO)2, respectively, under blue light irradiation. Treatment of 1Pr with two equivalents of PCy3 under blue light irradiation leads to reductive breakdown of the Fe−Fe bond to yield Fe(CO)3(PCy3)2, but in the dark at room temperature the desired product Fe2(μ‐SPr)2(PCy3)2(CO)4 may be isolated. Single crystal X‐ray structures were obtained for most family members of ‘butterfly’ {Fe2S2} cores. Cyclic voltammetry shows PMe3‐containing complexes undergo irreversible oxidation, whereas both PCy3 and PPh3 complexes show one (quasi)reversible oxidation, IR of in situ protonation showed COv blue shifting around 80–100 cm−1, while 31P{1H} NMR spectroscopy showed shifting to low field.

Atomic-scale wear behaviors of iron oxide through the atom-by-atom attrition and plastic deformation of nano-asperities

Atomic-scale wear, behaving distinctly from macroscale wear, has been gaining significant scientific interest. We previously proposed a semi-empirical wear model for covalent bonding materials, which primarily describes an interfacial-bond-dominant atomic-scale wear process. To assess the model's broader applicability on other material types, herein we selected the iron oxide (Fe2O3) as a representative ionic bonding material and conducted the large-scale atomistic simulations. The simulations unveiled two main atomic-scale wear mechanisms of Fe2O3: plastic deformation/cracking of nano-asperities induced by the asperity collision, and atom-by-atom attrition caused by the interfacial O–Fe bond formation. Crucially, our simulations proved effective in capturing the atom-by-atom attrition wear, thus confirming its validity for ionic materials and expanding its potential usefulness to a broader range of materials.

Synthesis and Electronic Structure of Bimetallic AuFe Nanocomposites

Au, Fe, and AuFe nanoparticles were obtained by metal vapor synthesis using acetone as the dispersion medium. The composition and electronic structure of the particles were studied by TEM, SEM, XPS, XANES, and EXAFS. The Au and Fe particles with average diameters of 5.3 and 1.8 nm, respectively, were obtained. According to X-ray diagnostic methods, gold was in the main Au0 state, and the Au+ and Au3+ states are present in small amounts while iron existed as mixture of non-stoichiometric oxides with states close to Fe2+ and Fe3+. Bimetallic nanoparticles were solid solutions with a disordered structure and Au–Fe–O and Au–O–Fe bonds. A carbon-containing shell was detected for all types of metal particles. The obtained materials may be promising for the development of improved antimicrobial agents and new methods for treating cancer diseases.

Revealing promotion of interfacial Pt–O–Fe oxygen bridge structure in PtFe/graphene synthesized by a four-electrode electrochemical system on water splitting

To promote kinetic rate of half reactions in water splitting, we synthesized a bifunctional PtFe/graphene with dual active sites by a facile self-designed four-electrode electrochemical method. Characterization data indicate interfacial oxygen bridge structure of Pt–O–Fe is expectedly formed and electrons transfer from Fe to Pt via this bridge structure. This unique interfacial structure not only regulates electronic structure of Pt and Fe, but also offers interfacial electron-transfer channel to improve overall conductivity, which essentially enhances intrinsic activity towards acidic HER and alkaline OER. For HER, the best Pt–Fe/G shows the mass activity of 4239.3 mA mg−1 at −0.063 V, 3.79 times higher than that of Pt/G (1118.5 mA mg−1) and 5.02 times higher than that of commercial Pt/C (843.1 mA mg−1) catalyst, respectively. Introduction of Fe to Pt decreases the energy barrier of HER process (ΔG∗), and results in conversion of rate-limiting step from H+ adsorption (Volmer step) to H∗ desorption (Tafel step). For OER, the greatest PtFe/G exhibits an overpotential of lower 26 mV (10 mA cm-2) than commercial RuO2 and its mass activity is 16.7 times higher than Fe/G. The formed Pt–O–Fe bond effectively elevates the electrophilic properties and facilitates adsorption of OH−, contributing to the change of rate-limiting step and enormous decrease of reaction activation energy (Ea). This work inspires researchers to construct efficient interfacial oxygen bridge structure to enhance electrocatalytic performance for water splitting and design novel electrochemical method for synthesis of graphene-based composites.

Large remnant polarization and improved dielectric, magnetic properties of Te-modified 0.7BiFeO3–0.3BaTiO3 ceramics

BiFeO3–BaTiO3 (BF–BT) ceramics, as a kind of binary ferroelectric material with excellent properties, have a wide range of applications. A novel Te-doped 0.7BiFe1−xTexO3–0.3BaTiO3 (x = 0–0.07) ceramics with enhanced ferroelectric properties were designed and synthesized via a solid-phase reaction. Results of X-ray diffraction and Rietveld refinement revealed a phase transition from the rhombohedra and tetragonal phases to a single tetragonal phase with increasing Te content, indicating the formation of a morphotropic phase boundary (MPB) in samples with x = 0–0.03. The fitting results of the X-ray photoelectron spectra showed that the Te introduction reduced the Fe2+ concentration and improved the insulating performance. Due to the Te-induced structure distortion of the rhombohedral phase and tetragonal phase, a large remnant polarization of 51 μC/cm2 is obtained at x = 0.01, which is superior to those reported in many studies on BF–BT bulk materials. The dielectric properties revealed that Te addition effectively adjusted the relaxation degree of the ceramics, showing an ideal relaxor ferroelectric behavior in samples with x = 0.05 and 0.07. Additionally, Te substitution reduced the Fe–O–Fe bond angle and the grain size, achieving enhanced ferromagnetism and affording the largest remnant magnetization in the case of x = 0.03, which is around six times that of the pure BF–BT ceramic.

Activation of peroxymonosulfate by FeVO3-x for the degradation of carbamazepine: Vanadium mediated electron shuttle and oxygen vacancy modulated interface chemistry

Fast Fe(III)/Fe(II) circulation in heterogeneous peroxymonosulfate (PMS) activation remains as a bottleneck issue that restricts the development of PMS based advanced oxidation processes. Herein, we proposed a facile ammonia reduction strategy and synthesized a novel FeVO3-x catalysts to activate PMS for the degradation of a typical pharmaceutical, carbamazepine (CBZ). Rapid CBZ removal could be achieved within 10 min, which outperforms most of the other iron or vanadium-based catalysts. Electron paramagnetic resonance analysis and chemical probe experiments revealed SO4•−, •OH, O2•− and high valent iron (Fe(IV)) were all generated in this system, but SO4•− and Fe(IV) primarily contributed to the degradation of CBZ. Besides, X-ray photoelectron spectroscopy and X-ray adsorption spectroscopy indicated that both the generated low-valent V provides and oxygen vacancy acted as superior electron donors and accelerated internal electron transfer via the unsaturated V−O−Fe bond. Finally, the proposed system also exhibited satisfactory performance in practical applications. This work provides a promising platform in heterogeneous PMS activation.

Mg-Fe Bonding in the MgFe(CO)n+ (n = 4-9) Cation Complexes: An Infrared Photodissociation Spectroscopic and Theoretical Study.

Heteronuclear magnesium-iron carbonyl cation complexes MgFe(CO)n+ (n = 4-9) are prepared in the gas phase and are detected by mass-selected infrared photodissociation spectroscopy in the carbonyl stretching frequency region. The geometric structures and the metal-metal bonding are discussed with the aid of quantum chemical calculations. The MgFe(CO)9+ cation is a coordinatively saturated complex. Each complex is characterized to contain more than one isomer. The small complexes (n = 4-6) possess the Mg-Fe bonded [(OC)n-4Mg-Fe(CO)4]+ and/or [(OC)n-5Mg-Fe(CO)5]+ structures with all the carbonyl ligands terminally bonded. For the larger complexes with n = 7-9, the [(OC)n-4Mg-Fe(CO)4]+ structure is the major isomer experimentally observed. In addition, the [(OC)n-5Mg-OC-Fe(CO)4]+ isomer involving a linear bridging carbonyl ligand is also characterized. Bonding analyses indicate that each [(OC)n-4Mg-Fe(CO)4]+ complex contains a Mg-Fe electron-sharing σ bond. The metal-metal bond is described as a Mg(+I)-Fe(0) bond in MgFe(CO)4+ and as a Mg(+II)-Fe(-I) bond in the larger n = 5-9 complexes.

Effect of air annealing on properties of maghemite nanoparticles produced by radiation-chemical method

Amorphous-crystalline nanoparticles (NPles) of maghemite (γ-Fe2O3) were successfully prepared by a radiation-chemical method using a precursor-heptahydrate of iron (II) sulfate. Synthesized NPles were quasi-spherical agglomerates 200–300 nm in size with an uneven surface covered with thin, porous, randomly oriented, elongated plates of irregular shape, with sharp vertices. The amorphous component of NPles included ultra-fine NPles maghemite about 2 nm in size. Stepwise annealing of the original nanopowder (NP) in air showed a phase transformation of NPles along the following path: maghemite + amorph (RT-150 °C) →amorph (200–500 °C) →hematite (570–1050 °C). The hematite NP produced after annealing at a temperature of 575 °C showed good texture characteristics: the specific surface area (SSA) increased from 21 to 36.8 m2/g, the pore volume increased from 0.04 to 0.15 cm3/g, while maintaining the particle nanosize of not more than 38 nm. X-ray photoelectron spectroscopy (XPS) showed the presence of the following elements on the surface of the synthesized NPles –S, C, O, Fe and N (N only in the original sample S0) and increased O–Fe bond with an increase in annealing temperature. The paramagnetic properties of the studied NPles indicate the prospect of their use as contrast agents in magnetic resonance imaging (MRI).

Engineering CSFe Bond Confinement Effect to Stabilize Metallic-Phase Sulfide for High Power Density Sodium-Ion Batteries.

Metallic-phase iron sulfide (e.g., Fe7 S8 ) is a promising candidate for high power density sodium storage anode due to the inherent metal electronic conductivity and unhindered sodium-ion diffusion kinetics. Nevertheless, long-cycle stability can not be achieved simultaneously while designing a fast-charging Fe7 S8 -based anode. Herein, Fe7 S8 encapsulated in carbon-sulfur bonds doped hollow carbon fibers (NHCFs-S-Fe7 S8 ) is designed and synthesized for sodium-ion storage. The NHCFs-S-Fe7 S8 including metallic-phase Fe7 S8 embrace higher electron specific conductivity, electrochemical reversibility, and fast sodium-ion diffusion. Moreover, the carbonaceous fibers with polar CSFe bonds of NHCFs-S-Fe7 S8 exhibit a fixed confinement effect for electrochemical conversion intermediates contributing to long cycle life. In conclusion, combined with theoretical study and experimental analysis, the multinomial optimized NHCFs-S-Fe7 S8 is demonstrated to integrate a suitable structure for higher capacity, fast charging, and longer cycle life. The full cell shows a power density of 1639.6Wkg-1 and an energy density of 204.5Whkg-1 , respectively, over 120 long cycles of stability at 1.1Ag-1 . The underlying mechanism of metal sulfide structure engineering is revealed by in-depth analysis, which provides constructive guidance for designing the next generation of durable high-power density sodium storage anodes.

Effect of La3+ substitution on structural, microstructure, magnetic properties, and microwave absorbing ability of yttrium iron garnet

Synthesis and characterization of lanthanum-doped yttrium iron garnet (YIG) in the compositional series of Y(3-x)La(x)Fe5O12 (x = 0.0, 0.1, 0.3, and 0.5) were carried out. All compositions were made by using solid state reaction method with ball-milling technique. The phase formation, surface morphology, magnetic properties, and microwave absorbing ability of all compositions were characterized by using X-ray diffractometer, scanning electron microscope, vibrating sample magnetometer, and Vector network analyzer. The results reveal that all compositions are crystallized into Y3Fe5O12 phase (space group Ia-3d (230). It was observed that the lattice constant is increased from 1.2373 to 1.2421 nm with the increase of lanthanum substitution level from x = 0.0 to 0.5. The crystallite size of Y(3-x)La(x)Fe5O12 series calculated by Scherrer method is found to decrease from 78 nm in x = 0.0 to 63 nm in x = 0.5. The particle size distribution from the surface morphology image analysis is shifted to lower-range number with the increase of lanthanum substitution level from x = 0.0 to 0.5. The substitution process also affects the lattice distortion in La-doped samples and changes the bond angles and bond lengths of the YIG structure. As the results, a linear correlation between the Fe'–O–Fe bond angle with magnetic properties parameters of saturation magnetization (Ms) and remanence magnetization (Mr) was studied. Due to the lanthanum substitution process, all La3+-doped samples possess higher Ms and Mr values compared to the original composition. The results of Vector network analyzer show that the improvement of the Ms and Mr plays an important role in enhancing the microwave absorbing ability of the materials. The minimum RL changed from –8.22 dB (∼ 85.22% microwave absorption) in x = 0.0 to -14.21 dB (∼ 96.25% microwave absorption) in x = 0.5. The enhancement mainly ascribed to the natural magnetic resonance loss and dipole-polarization loss due to the substitution process. The decreasing particle size also enhanced the microwave absorbing ability of the La-doped samples via multiple-reflections mechanism.

Isolation of dissolved organic matter from aqueous solution by precipitation with FeCl3: mechanisms and significance in environmental perspectives

Ferric ions can bind strongly with dissolved organic matter (DOM), including humic acids (HA), fulvic acids (FA), and protein-like substances, whereas isolation of Fe-DOM precipitates (Fe-DOMP) and their biochemical characteristics remain unclear. In this work FeCl3 was used to isolate DOM components from various sources, including river, lake, soil, cow dung, and standard tryptophan and tyrosine, through precipitation at pH 7.5–8.5. The Fe-DOMP contribute to total DOM by approximately 38.6–93.8% of FA, 76.2% of HA and 25.0–30.4% of tryptophan and tyrosine, whilst fluorescence spectra allowed to monitor/discriminate the various DOM fractions in the samples. The relative intensity of the main infrared peaks such as 3406‒3383 cm−1 (aromatic OH), 1689‒1635 cm−1 (‒COOH), 1523–1504 cm−1 (amide) and 1176–1033 cm−1 (‒S=O) show either to decline or disappear in Fe‒DOMP. These results suggest the occurrence of Fe bonds with various functional groups of DOM, indicating the formation of π–d electron bonding systems of different strengths in Fe‒DOMP. The novel method used for isolation of Fe-DOMP shows promising in opening a new frontier both at laboratory and industrial purposes. Furthermore, results obtained may provide a better understanding of metal–organic complexes involved in the regulation of the long-term stabilization/sequestration of DOM in soils and waters.

Stabilizing Single-Atomic Pt by Forming PtFe Bonds for Efficient Diboration of Alkynes.

Precisely tailoring the oxidation state of single-atomic metal in heterogeneous catalysis is an efficient way to stabilize the single-atomic site and promote their activity, but realizing this approach remains a grand challenge to date. Herein, a class of stable single-atomic catalysts with well-tuned oxidation state of Pt by forming PtFe atomic bondsisreported, which are supported by defective Fe2 O3 nanosheets on reduced graphene oxide (PFARFNs). These as-synthesized materials can greatly enhance the catalytic activity, stability, and selectivity for the diboration of alkynes. The PFARFNs exhibit high conversion of 99% at 100°C with an outstanding turnover frequency (TOF) of 545h-1 , and a relatively high conversion of 58% at room temperature (25°C) with a TOF of 310h-1 , which has beenhardly achieved previously. Through both experimental and theoretical investigation, it is demonstrated that the fast electron transfer from Fe to Pt in Fe-Pt-O atomic sites in PFARFNs can not only stabilize the single-atomic Pt, but also significantly improve their catalytic activity.

Utilizing Fe2O3 in phosphate-based glasses to enhance biocompatibility and gamma-ray absorption characteristics: A step towards understanding of Na2O/Fe2O3 translocation in P2O5–CaO–Na2O glass system

In recent years, bioactive glasses have been used in several different contexts, from dental applications to FDA-approved bone augmentation treatments. We report the incorporation consequences of Fe2O3 into P2O5–CaO–Na2O glasses to enhance the biocompatibility and gamma-ray absorption characteristics for potential medical and dental application. Phosphate-based glasses with a composition of 50P2O5·30CaO·(20-x)Na2O.(x)Fe2O3 were prepared using the melt-quenching process; x varies from 0 to 5 mol% with 1 mol% incremental increase. The fundamental biological and physical properties such as cell viability, attachment, and gamma-ray absorption of these glasses were investigated. The number and spreading of human dental pulp stem cells and human fetal osteoblasts, indicated by the density of actin-stained cytoplasm, increased on glasses with more Fe2O3 content particularly for those with 4 and 5 mol%. Incorporation of Fe2O3 into the glass system provided a significant improvement in hDPSCs and hFOBs viability. The improved cell attachment and viability with increasing the Fe2O3 content could be attributed to the enhanced durability of glasses with the formation of more hydration resistant P–O–Fe bonds. The mass attenuation coefficient values of the 50P2O5·30CaO·15Na2O·5Fe2O3 glass with a 5% Fe2O3 contribution are found to be the highest over the whole investigated energy range. The half value layer values of the 50P2O5·30CaO·15Na2O·5Fe2O3 glass are the lowest and hence more favorable. It can be concluded that increasing the Fe2O3 mol% in the P2O5–CaO–Na2O glass system is a useful method for increasing the biocompatibility and gamma-ray attenuation characteristics of P2O5–CaO–Na2O bioactive glasses for medical and dental applications.

Efficacious Reduction of Ferric Ions by Molybdenum Carbide in the Peroxydisulfate Fenton-Like Reaction for Dexamethasone Degradation

The tardy Fe2+ regeneration and the limited pH range confine the practical application of Fe-based homogenous Fenton-like reaction performance. To surmount the abovementioned obstacles, we applied molybdenum carbide (β-Mo2C) as the cocatalyst to boost Fe3+ reduction in the activation of peroxydisulfate (PDS) for the efficient degradation of dexamethasone (DXM). The proposed Fe3+/PDS/β-Mo2C can remove more than 90% DXM in the wide pH range (3.4 to 9.4). Electron spin resonance analysis and probe and quenching tests comprehensively demonstrated that a series of reactive species (•OH, SO4•–, O2•–, 1O2, and Fe(IV)) were formed during the synergistic process, and SO4•– was the leading role. The circulation of Fe3+/Fe2+ was driven by the exposed sites of Mo2+/Mo4+ on the β-Mo2C, which further promoted the PDS activation. The reaction mechanism was clarified by various characterizations and density functional theory calculation, which indicated that the adsorption between Fe3+ and β-Mo2C could form Mo–Fe bonds and lengthen Fe–O and then improve the electron transport from β-Mo2C to Fe3+ and boost Fe3+ reduction. The reactivity and stability of β-Mo2C was higher than those of popular Mo-based materials. This work represents an attempt and possibility for Mo-based inorganic cocatalysis of advanced oxidation processes.

Iron-Rich Biochar to Adsorb Volatile Organic Compounds Emitted from Asphalt-Surfaced Areas

This study introduces iron-rich biochar to selectively adsorb some volatile organic compounds (VOCs) emitted from asphalt-surfaced areas. Adsorption and retention of VOCs can improve the air quality while reducing asphalt’s mass loss which compromises asphalt’s durability. The iron-rich biochar was made from a hybrid feedstock of Cyanidioschyzon merolae (CM) algae and swine manure (SM) with a blend of 20:80 CM/SM, showing the highest biochar yield of 27 wt % and the highest metal content of Fe (21.8 g kg–1). Comparison of VOC adsorption of iron-rich biochar and low-iron biochar shows the significant role of Fe content in adsorption of VOCs. When the iron-rich biochar was introduced to asphalt, a total emission reduction of 76% was observed; this number was only 59% when low-iron biochar was used. The superiority of iron-rich biochar over low-iron biochar in adsorbing volatiles is observed for some specific volatiles such as non-polar aromatics in our experiment. The dominant contribution of lightweight cyclic aromatics and alkanes in bitumen emissions indicates that minimizing the VOC emissions from saturate and aromatic fractions of bitumen could be a key factor in reducing the VOCs from asphalt. The hybrid biomass feedstock used here is also a nitrogen-rich substance containing abundant N sites to coordinate with Fe to form −C–N–Fe bonds. To understand the role of N–Fe functionals in the higher efficacy of Fe-rich biochar, density functional theory (DFT) calculations were performed on three O-containing compounds (benzoic acid, benzofuran, and hexanal) and three S-containing compounds (dibenzothiophene, 3-pentylthiophene, and hexanethiol). Based on DFT results, the adsorption energies of VOCs on active sites of Fe–biochar (containing −N–Fe functionals) are 8 to 10 times higher than those for pristine biochar (containing just N groups). It was also found that the presence of iron stimulates the catalytic performance of biochar, as evidenced by our DFT results, indicating degradation of dibenzothiophene and hexanethiol on the N–Fe active zones of iron-rich biochar. Application of iron-rich biochar can suppress the volatiles emitted from asphalt-surfaced areas; this in turn can improve the air quality and extend the service life of roadway infrastructures. Therefore, the study outcomes can promote built environment’ sustainability and public health.