Speeding up the prediction of C-O cleavage through bond valence and charge on iron carbides

The activation of CO on iron-based materials is a key elementary reaction for many chemical processes.We investigate CO adsorption and dissociation on a series of Fe,Fe_(3)C,Fe_(5)C_(2),and Fe_(2)C catalysts through density functional theory calculations.We detect dramatically different performances for CO adsorption and activation on diverse surfaces and sites.The activation of CO is dependent on the local coordination of the molecule to the surface and on the bulk phase of the underlying catalyst.The bulk properties and the different local bonding environments lead to varying interactions between the adsorbed CO and the surface and thus yielding different activation levels of the C-O bond.We also examine the prediction of CO adsorption on different types of Fe-based catalysts by machine learning through linear regression models.We combine the features originating from surfaces and bulk phases to enhance the prediction of the activation energies and perform eight different linear regressions utilizing the feature engineering of polynomial representations.Among them,a ridge linear regression model with2nd-degree polynomial feature generation predicted the best CO activation energy with a mean absolute error of 0.269 eV.

Density functional theory for adsorption of HCHO on the FeO(100) surface

The density functional theory （DFT） and periodic slab model were used to get information concerning the adsorption of HCHO on the FeO（100） surface. A preferred η^2-（C,O）-di-σ four-membered ring adsorption conformation on the Fe-top site was found to be the most favorable structure with the predicted adsorption energy of 210.7 kJ/mol. The analysis of density of states, Mulliken population, and vibrational frequencies before and after adsorption showed clear weakening of the carbonyl bond, and high sp^3 character on the carbon atom.

Structure and Coordination Investigation of Iron-ion Tinting Principle in Ferreous Glass

The tinting phenomena of iron oxide contained glasses were studied from aspects of the electronic configuration, the iron ions coordination fields and the ions structure in glass. Several iron ion tinting forms at different redox or COD (chemical oxygen demand) conditions and their influential factors were given necessary explanations. The results reveal that the Fe^(3+)-O-Fe^(2+) structure is the real tinting reason of iron involved glasses, whereas the Si^(4+)-O-Fe^(3+) and Si^(4+)-O-Fe^(2+) formulations modify the glass colours. Under oxidizing melting condition, the amount of 4/6-coordinated Fe^(3+) increases and makes the glass colour yellowish. Conversely, reducing melting condition makes the 6-coordinated Fe^(2+) increased and gives much blue tint to the glass. The conventional tank furnace melting the very strong reducing condition, which is of high COD glass batch, is not suitable. The high ratio of ferrous/ferric in glass can be obtained with a new refining technology which contains no or little amount of refining agent.

Effect of content and spin state of iron on electronic properties and floatability of iron-bearing sphalerite:A DFT+U study

Iron is an impurity widely occurred in sphalerite,and its effect on sphalerite flotation is complex.In this work,the effects of iron content and spin state on electronic properties and floatability of iron-bearing sphalerite are comprehensively studied using density functional theory Hubbard U(DFT+U)calculations combined with coordination chemistry flotation.The band gap of ideal sphalerite is 3.723 eV,and thus electron transition is difficult to occur,resulting in poor floatability.The results suggest the band gap of sphalerite decreases with increasing iron content.For low iron content,the decreased band gap facilitates electron transition;at this case,Fe^(2+)in a high-spin state possesses oneπelectron pair,which can form a weakπ-backbonding with xanthate,causing increasing floatability.However,for medium and high iron-bearing sphalerite,with the further decrease of band gap,Fe^(2+)is oxidized to Fe^(3+)due to electrochemical interaction,and henceπ-backbonding is eliminated,leading to lower floatability of iron-bearing sphalerite,which is consistent with the flotation experimental results.This work could give a deeper understanding of how sphalerite flotation behaviors are affected by iron content.

Iron phthalocyanine-catalyzed radical phosphinoylazidation of alkenes:A facile synthesis of β-azido-phosphine oxide with a fast azido transfer step

Phosphinoylazidation of alkenes is a direct method to build nitrogen-and phosphorus-containing compounds from feed-stock chemicals.Notwithstanding the advances in other phosphinyl radical related difunctionalization of alkenes,catalytic phosphinoylazidation of alkenes has not yet been reported.Here,we describe the first iron-catalyzed intermolecular phosphinoylazidation of styrenes and unactivated alkenes.The method is practically useful and requires a relatively low loading of catalyst.Mechanistic studies confirmed the radical nature of the reaction and disclosed the unusually low activation energy 4.8 kcal/mol of radical azido group transfer from the azidyl iron(III)phthalocyanine species(PcFeulN3)to a benzylic radical.This work may help to clarify the mechanism of iron-catalyzed azidation,inspire other mechanism studies and spur further synthetic applications.

Amino acids modified nanoscale zero-valent iron:Density functional theory calculations,experimental synthesis and application in the Fenton-like degradation of organic solvents

To improve the adsorption and catalytic performance of heterogeneous Fenton-like catalysts for oil wastes,amino acids were used to modify nanoscale zero-valent iron(AA@Fe^(0)),which were applied in the Fenton-like degradation of organic solvents(tributyl phosphate and n-dodecane,named TBP and DD).Twelve amino acids,i.e.,glycine(Gly),alanine(Ala),leucine(Leu),proline(Pro),phenylalanine(Phe),methionine(Met),cysteine(Cys),asparagine(Asn),serine(Ser),glutamic acid(Glu),lysine(Lys)and arginine(Arg),were selected and calculated by density functional theory(DFT).The optimized structure,charge distribution,the highest occupied molecular orbital(HOMO),the lowest unoccupied molecular orbital(LUMO),interaction region indicator(IRI)isosurface map and adsorption energy of AA@Fe^(0),AA@Fe^(0)-TBP and AA@Fe^(0)-DD were studied,which indicated that Fe is more likely to approach and charge transfer with-COO and-NH_(3) on theα-carbon of amino acids.There is strong attraction between Fe and–COO,and Van der Waals force between Fe and-NH_(3),respectively.In the interaction of AA@Fe^(0)with TBP and DD,Van der Waal force plays an important role.AA@Fe^(0)was synthesized in laboratory and characterized to investigate physicochemical properties.In Fenton-like degradation of organic solvents,the change of COD in water phase during the degradation process as well as the volume of the organic phase after the reaction were investigated.The results of calculations combined with experiments showed that Ser-modified Fe^(0)performed the best in these amino acids,with 98%removal of organic solvents.A possible catalytic mechanism was proposed in which amino acids acted a linking role between Fe and organic solvents,activating H_(2)O_(2)to generate hydroxyl radicals for the degradation of organic solvents.

Differences in the adsorption of FePc on coinage metal surfaces

A study of the electronic and structural properties of iron phthalocyanine （FePc） molecules adsorbed on coinage metal surfaces Cu （100） and Cu （110） has been conducted by means of density functional theory calculations. The strength of the molecule-substrate interactions is interpreted in terms of the lateral adsorption geometry and the site specific electronic structure of the molecule. In the case of FePc on a （100）-oriented copper surface, the benzopyrrole leg is found to be oriented at an angle of 9°or 3°from the [01-1] substrate direction. Further, an upward bend in the molecular plane ranging from 7° to 10°is also observed; giving an almost buckled shape to the molecule. However, in the case of FePc on Cu （110）, neither a bend nor a sizable rotation is observed. From the knowledge of the principle structural and electronic properties, it is concluded that FePc-Cu （100） interaction is relatively stronger than FePc-Cu （110） interaction, which is further evidenced by the charge transfer, work function changes, changes in the shape of the adsorbed molecular orbitals, and the orbital shifts. Furthermore, density of states analysis shows that the valence band level shift is surface- and site-dependent.

Role of Ga-doping in iron-gallium alloy clusters

The structural and magnetic properties of Fen-mCam （n = 3 - 6, m = 0 - 2; n = 13, m = 0 - 3） alloy clusters have been studied using density functional theory. The substitutional doping is favourable for small clusters with up to six atoms at low Ga concentration and substitutional Ga atoms in 13-atom clusters prefer surface sites. The Ca-doping generally could reduce the energetic stability but enhance the electronic stability of Fe clusters, along with a decrease of the local magnetic moments of Fe atoms around Ca dopants. These findings provide a microscopic insight into Fe-Ga alloys which are well：known magnetostriction materials.

Comparison of band structure and superconductivity in FeSe_(0.5)Te_(0.5) and FeS

The isovalent iron chalcogenides, FeSe0.5Te0.5 and FeS, share similar lattice structures but behave very differently in superconducting properties. We study the underlying mechanism theoretically. By first principle calculations and tight-binding fitting, we find the spectral weight of the dX2-Y2 orbital changes remarkably in these compounds. While there are both electron and hole pockets in FeSe0.5Te0.5 and FeS, a small hole pocket with a mainly dX2-Y2 character is absent in FeS. We find the spectral weights of dX2-Y2 orbital change remarkably, which contribute to electron and hole pockets in FeSe0.5Te0.5 but only to electron pockets in FeS. We then perform random-phase-approximation and unbiased singular-mode functional renormalization group calculations to investigate possible superconducting instabilities that may be triggered by electron-electron interactions on top of such bare band structures. For FeSe0.5Te0.5, we find a fully gapped s-wave pairing that can be associated with spin fluctuations connecting electron and hole pockets. For FeS, however, a nodal dxy （or dx2-y2 in an unfolded Broullin zone） is favorable and can be related to spin fluctuations connecting the electron pockets around the corner of the Brillouin zone. Apart from the difference in chacogenide elements, we propose the main source of the difference is from the dX2-Y2 orbital, which tunes the Fermi surface nesting vector and then influences the dominant pairing symmetry.

Fuzzy TOPSIS method to primary crusher selection for Golegohar Iron Mine(Iran)

Selection of the crusher required a great deal of design regarding to the mine planning. Selection of suitable primary crusher from all of available primary crushers is a multi-criterion decision making(MCDM) problem. The present work explores the use of technique for order performance by similarity to ideal solution(TOPSIS) with fuzzy set theory to select best primary crusher for Golegohar Iron Mine in Iran. Gyratory, double toggle jaw, single toggle jaw, high speed roll crusher, low speed sizer, impact crusher, hammer mill and feeder breaker crushers have been considered as alternatives. Also, the capacity, feed size, product size, rock compressive strength, abrasion index and application of primary crusher for mobile plants were considered as criteria for solution of this MCDM problem. To determine the order of the alternatives, closeness coefficient is defined by calculating the distances to the fuzzy positive ideal solution(FPIS) and fuzzy negative ideal solution(FNIS). Results of our work based on fuzzy TOPSIS method show that the gyratory is the best primary crusher for the studied mine.

High-resolution angle-resolved photoemission study of oxygen adsorbed Fe/MgO(001)

We have investigated the electronic states of clean Fe(001) and oxygen adsorbed Fe(001)–p(1 × 1)-O films epitaxially grown on MgO(001) substrates by means of polarization-dependent angle-resolved photoemission spectroscopy(ARPES)and extensive density-functional theory(DFT) calculations. The observed Fermi surfaces and band dispersions of pure Fe near the Fermi level were modified upon oxygen adsorption. By the detailed comparison of ARPES and DFT results of the oxygen adsorbed Fe surface, we have clarified the orbital-dependent p–d hybridization in the topmost and second Fe layers.Furthermore, the observed energy levels and Fermi wave numbers for the oxygen adsorbed Fe surface were deviated from the DFT calculations depending on the orbital characters and momentum directions, indicating an anisotropic interplay of the electron correlation and p–d hybridization effects in the surface region.

The Cluster Fe₂Si₁₈as the New Quantum Bit System

Multiconfiguration quantum chemical calculation of geometry and electron properties of Fe2Si18 cluster indicates on the predictable change of spin states as a function of the excitation energy beginning from ground state with the total spin S = 4. The charges on the two Fe atoms are quite different as well as the charge distribution on the surrounding Si atoms. Nevertheless the total dipole moment of the cluster is a monotonically decreasing function of the excitation energy and it reaches practically zero value in the first singlet state in which the cluster represents a new version of a quibit system.

硫掺杂铁基单原子催化剂结构与催化活性的密度泛函理论研究

通过密度泛函理论计算研究了硫原子掺杂对铁基单原子催化剂结构稳定性和催化活性的影响.采用结构优化和自由能计算的方法,评估了硫掺杂构型的热力学和电化学稳定性.结果表明:硫原子呈卫星式排布环绕单原子催化剂活性位点,形成稳定的催化剂结构,并对活性位点的电子结构进行调控.进一步比较了硫掺杂前后的催化活性,结果显示硫掺杂能够显著降低氧还原反应的过电势,特别是对称性破缺的体系表现出最低的过电势.

Phosphorus Removal of High Phosphorus Iron Ore by Gas-Based Reduction and Melt Separation

A new method （gas-based separation plus melt separation） has been proposed to remove phosphorus of the high phosphorus iron ore which was 1.25 % of phosphorus content and 50. 0% of iron content. HSC chemistry package and the coexistence theory of slag structure were adopted for theoretical analysis. The gas-based reduction was carried out using a fixed bed reactor and the ore sample of 80 g with an average particle size of 2 mm were reduced using CO or H2 at temperature of 1 073 K for 5 hours. 50 g of the reduced sample with 3.0% CaO as additive was then subjected to melt separation in an electric furnace at temperature of 1 873 K under Ar atmosphere. In each run, SEM, EDS, optical microscopic examination and chemical analysis of the reduced ore sample, the metal sample and the slag sample were conducted. Results of all gas-based reduction experiments showed that iron metallization ratios were some 65% and the phosphorus compounds in the ore remained unchanged. It was agreed well with the simula- tions except for the iron metallization rate being less than predicted value; this difference was attributed to kinetics. Results of melt separation experiments showed that P content in metal samples is 0.33% （metal sample from H2 reduction product） and 0.27% （metal sample from CO reduction product）. The phosphorus partition ratios of both cases were less than predicted values. Some P in the metal samples existed as slag inclusion was considered to be the reason for this discrepancy.

轴向配体对铁卟啉催化氧化环己烷和苯C—H键的影响

采用密度泛函理论方法系统研究了带有不同轴向配体(F^(-)、Cl^(-)、CH_(3)COO^(-)、SCH^(-)_(3))的铁卟啉作为仿生催化剂催化氧化环己烷和苯C—H键的反应,重点考察了轴向配体对高价铁-氧卟啉几何结构和电子结构的影响,以及轴向配体影响高价铁-氧卟啉氧化环己烷和苯C—H键反应活性的本质差异。相较于其他轴向配体,F^(-)作为轴向配体使高价铁-氧卟啉具有更高的活性,更易于氧化环己烷和苯的C—H键。与苯环C—H键氧化反应相比,改变轴向配体对环己烷C—H键氧化反应的活性影响更大,且轴向配体主要通过影响过渡态结构中环己烷的形变能来改变环己烷C—H键氧化反应的活化能。而在苯环C—H键氧化反应中,轴向配体主要影响过渡态结构中高价铁-氧卟啉与苯的相互作用能以及苯分子的形变能。

基于UbD理论的化学逆向教学设计--以“铁及其化合物”单元教学为例

以铁及其化合物为例,基于UbD理论进行了单元教学设计。以元素观为大概念,明确学习优先次序,增设表现性任务,融合WHERETO要素,构建分类观-转化观-元素观的元素化合物分析模型,得到元素化合物的单元教学启示:聚焦核心大概念,建立认知模型;注重理解多维度,培育高阶思维;评价融入教与学,落实“教、学、评”一体化。

Nitrogen reduction reaction on small iron clusters supported by N-doped graphene:A theoretical study of the atomically precise active-site mechanism

Nonprecious metal catalysts are known of significance for electrochemical N2 reduction reaction(NRR)of which the mechanism has been illustrated by ongoing investigations of single atom catalysis.However,it remains challenging to fully understand the size-dependent synergistic effect of active sites inherited in substantial nanocatalysts.In this work,four types of small iron clusters Fen(n=1–4)supported on nitrogen-doped graphene sheets are constructed to figure out the size dependence and synergistic effect of active sites for NRR catalytic activities.It is revealed that Fe3 and Fe4 clusters on N4G supports exhibit higher NRR activity than single-iron atom and iron dimer clusters,showing lowered limiting potential and restricted hydrogen evolution reaction(HER)which is a competitive reaction channel.In particular,the Fe4-N4G displays outstanding NRR performance for“side-on”adsorption of N2 with a small limiting potential(−0.45 V).Besides the specific structure and strong interface interaction within the Fe4-N4G itself,the high NRR activity is associated with the unique bonding/antibonding orbital interactions of N-N and N-Fe for the adsorptive N2 and NNH intermediates,as well as relatively large charge transfer between N2 and the cluster Fe4-N4G.

Fabrication of highly effective electrodes for iron chromium redox flow battery

Iron-chromium redox flow batteries(ICRFBs)have emerged as promising energy storage devices due to their safety,environmental protection,and reliable performance.The carbon cloth(CC),often used in ICRFBs as the electrode,provides a suitable platform for electrochemical processes owing to its high surface area and interconnected porous structure.However,the CC electrodes have issues,such as,insufficient electron transfer performance,which limits their industrial application.Here,we employed silicic acid etching to carve dense nano-porous structures on the surface of CC electrodes based on the favorable design of ICRFBs and the fundamental principles of electrode polarization losses.As a result,we developed a multifunctional carbon cloth electrode with abundant vacancies,notably enhancing the performance of the battery.The fabricated electrode showcased a wealth of defect sites and superior electronic transport properties,offering an extensive and effective reaction area for rapidly flowing electrolytes.With an electrode compression ratio of 40%and the highest current density in ICRFBs so far(140 mA·cm^(-2)),the battery achieved the average energy efficiency of 81.3%,11.24%enhancement over the previously published work.Furthermore,throughout 100 charge-discharge cycles,the average energy efficiency degradation was negligible(~0.04%),which has the potential to become the most promising candidate for large-scale and long-term electrochemical energy storage applications.

基于混沌理论与麻雀优化K-means算法的变压器铁心松动缺陷分析方法

为了更加有效地对变压器铁心状态进行分析,提出一种基于混沌理论与麻雀优化K-means算法的变压器铁心松动缺陷特征分析方法。首先,运用C-C法求解重构相空间的嵌入维数与延迟时间,重构变压器振动信号的相空间。其次,计算变压器振动信号的最大Lyapunov指数来判断系统是否具有混沌特性,选取关联维数、Kolmogorov熵作为一组混沌特征以识别铁心的松动程度。再次,将麻雀搜索算法引入K-means聚类算法优化初始中心簇的选取并使用簇中心与簇类点的位移平均值作为描述变压器铁心松动状态的定量特征。最后,将两组特征结合起来形成变压器铁心松动故障的诊断指标,为变压器铁心的松动故障诊断提供理论依据,并投入分类器进行故障诊断,验证两组特征结合的优越性。

基于“扶阳”理论应用砭石熨摩中药透入法联合八段锦治疗1例胃痞病患者的护理体会

本文总结基于“扶阳”理论应用砭石熨摩中药透入法联合八段锦治疗1例胃痞病患者的护理经验。在常规护理基础上,通过对该患者进行症状、心理、睡眠等评估,在“扶阳”理论指导下,实施砭石熨摩中药透入法联合八段锦中医护理技术,旨在缓解患者上腹胀满症状,改善健康状况。