First-Principles Investigation of Charge Transfer Mechanism of B-Doped 3C-SiC Semiconductor Material

This study delves into the charge transfer mechanism of boron (B)-doped 3C-SiC through first-principles investigations. We explore the effects of B doping on the electronic properties of 3C-SiC, focusing on a 12.5% impurity concentration. Our comprehensive analysis encompasses structural properties, electronic band structures, and charge density distributions. The optimized lattice constant and band gap energy of 3C-SiC were found to be 4.373 Å and 1.36 eV respectively, which is in agreement with previous research (Bui, 2012;Muchiri et al., 2018). Our results show that B doping narrows the band gap, enhances electrical conductivity, and influences charge transfer interactions. The charge density analysis reveals substantial interactions between B dopants and surrounding carbon atoms. This work not only enhances our understanding of the material’s electronic properties, but also highlights the importance of charge density analysis for characterizing charge transfer mechanisms and their implications in the 3C-SiC semiconductors.

丙烯酰胺基互穿网络的制备及对Fe^(3+)的吸附

以磺酸基甜菜碱为互穿物,以丙烯酰胺(AM)、N-乙烯基吡咯烷酮和苯乙烯为单体,过硫酸铵为引发剂,N,N′-亚甲基双丙烯酰胺为交联剂,通过两步聚合法制备AM基互穿网络。该网络可对Fe^(3+)形成高效且快速的吸附,25℃下用量为0.2 g/50 mL,吸附2.5 h后达到平衡,最大吸附量为1.90 mg/g,此时吸附率可达76%;在50000 mg/L的矿化度下,对Fe^(3+)的吸附量仍能达到1.76 mg/g,在实际应用中,Fe^(3+)去除率可达80%以上。Fe^(3+)与互穿网络中的氨基、羰基和磺酸基形成配位键,吸附后荧光强度明显减小,并以单分子层形式吸附,化学控制为主,符合Langmuir等温吸附模型和准二级动力学模型。

Fe^(3+)掺杂的聚氨基吡咯纳米粒子用于原位乳腺癌的磁共振成像和光热治疗

利用铁离子诱发的氨基吡咯氧化聚合反应及铁离子与聚氨基吡咯间的配位作用制备了尺寸均一的铁离子掺杂聚氨基吡咯纳米粒子(Fe/Ppy-NH_(2)NPs).Fe/Ppy-NH_(2)NPs的胶体稳定性良好,其中铁离子的质量分数高达17.4%.铁离子在Fe/Ppy-NH_(2)NPs中的大量掺杂,一方面,能够增强其在近红外光区的消光能力,Fe/Ppy-NH_(2)NPs的光热转化效率高达37.9%,是一种良好的光热试剂,能够实现对肿瘤的光热治疗;另一方面,铁离子3d轨道中存在的单电子能够降低纵向弛豫时间,Fe/Ppy-NH_(2)NPs能够作为T_(1)加权的磁共振成像造影剂,实现对肿瘤的定位.Fe/Ppy-NH_(2)NPs在对原位乳腺癌的磁共振成像和光热治疗中展现了良好的效果.

基于油茶茶枯的生物质碳点制备及对Fe3+检测研究

以油茶茶枯粉末为碳源,通过一步水热法合成了新型生物质碳点(CDs),研究了油茶茶枯粉末的加入量、水热反应时间、水热反应温度对CDs荧光强度的影响,进而采用透射电子显微镜(TEM)、X射线粉末衍射(XRD)、傅里叶变换红外光谱(FT-IR)、荧光光谱、紫外-可见光吸收光谱(UV-Vis)等对所制备的CDs进行了结构和光学特性表征。实验结果表明,所制备的CDs粒径分布均匀,平均尺寸为1.5 nm,在365 nm的紫外灯照射下呈现出明亮的蓝光发射,且在较宽的pH范围内具有良好的稳定性。Fe^(3+)离子对所制备的油茶茶枯CDs有荧光猝灭作用,CDs的荧光强度与Fe^(3+)在0~30和50~90μmol/L范围内均呈现良好的线性关系。当Fe^(3+)物质的量的浓度为0~30μmol/L时,检出限为5.25μmol/L,相关系数(R^(2))为0.9994,Fe^(3+)物质的量的浓度为50~90μmol/L时,检出限为5.26μmol/L,R^(2)为0.9982,可作为荧光纳米探针检测Fe^(3+)金属离子。

改性Fe_(3)O_(4)@MIL-100(Fe)对Cu(Ⅱ)的吸附研究

传统液相吸附材料在吸附Cu(Ⅱ)时存在吸附性能差、难分离回收等问题,而金属有机框架(MOF)在重金属离子吸附领域极具发展潜力。基于此,研究通过经济环保低能耗的室温水相法以Fe_(3)O_(4)为核制备Fe_(3)O_(4)@MIL-100(Fe)磁性材料,通过合成后修饰的方法改性得到NH2-Fe_(3)O_(4)@MIL-100(Fe),采用XRD、FT-IR、SEM、TEM、VSM和EA等对改性前后材料进行表征,探究pH、时间、浓度、温度对改性前后材料吸附Cu(Ⅱ)性能的影响。结果表明,由于NH2-Fe_(3)O_(4)@MIL-100(Fe)与Cu(Ⅱ)之间的配位和静电作用,其对Cu(Ⅱ)的吸附容量(46.77 mg/g)显著高于改性前。改性前后材料对Cu(Ⅱ)的吸附均符合伪二级动力学模型和Freundlich吸附模型;热力学研究表明,改性后材料对Cu(Ⅱ)的吸附为自发吸热过程,而改性前为自发放热过程。此外,经过5次吸附-解吸循环后,NH2-Fe_(3)O_(4)@MIL-100(Fe)对Cu(Ⅱ)的吸附容量仍略高于Fe_(3)O_(4)@MIL-100(Fe)。

Self-assembled S-scheme In_(2.77)S_(4)/K^(+)-doped g-C_(3)N_(4)photocatalyst with selective O_(2) reduction pathway for efficient H_(2)O_(2) production using water and air

The development of an efficient artificial H_(2)O_(2) photosynthesis system is a challenging work using H_(2)O and O_(2) as starting materials.Herein,3D In_(2.77)S_(4) nanoflower precursor was in-situ deposited on K^(+)-doped g-C_(3)N_(4)(KCN)nanosheets using a solvothermal method,then In_(2.77)S_(4)/KCN(IS/KCN)het-erojunction with an intimate interface was obtained after a calcination process.The investigation shows that the photocatalytic H_(2)O_(2) production rate of 50IS/KCN can reach up to 1.36 mmol g^(-1)h^(-1)without any sacrificial reagents under visible light irradiation,which is 9.2 times and 4.1 times higher than that of KCN and In_(2.77)S_(4)/respectively.The enhanced activity of the above composite can be mainly attributed to the S-scheme charge transfer route between KCN and In_(2.77)S_(4) according to density functional theory calculations,electron paramagnetic resonance and free radical capture tests,leading to an expanded light response range and rapid charge separation at their interface,as well as preserving the active electrons and holes for H_(2)O_(2) production.Besides,the unique 3D nanostructure and surface hydrophobicity of IS/KCN facilitate the diffusion and transportation of O_(2) around the active centers,the energy barriers of O_(2) protonation and H_(2)O_(2) desorption steps are ef-fectively reduced over the composite.In addition,this system also exhibits excellent light harvesting ability and stability.This work provides a potential strategy to explore a sustainable H_(2)O_(2) photo-synthesis pathway through the design of heterojunctions with intimate interfaces and desired reac-tion thermodynamics and kinetics.

球磨制备磁性Fe_(3)O_(4)/Fe-藻渣碳基功能材料及其对养殖废水中铜和锌的吸附

本文以藻渣为原材料制备磁性Fe_(3)O_(4)/Fe-藻渣碳基功能材料,及其对养殖废水中铜和锌的吸附效果。通过改变铜和锌模拟废水初始浓度、初始pH值、吸附时间、磁性Fe_(3)O_(4)/Fe-藻渣碳基功能材料投加量,得到最佳吸附条件,结合吸附动力学模型和吸附等温模型拟合参数,分析磁性Fe_(3)O_(4)/Fe-藻渣碳基功能材料对铜和锌的吸附性能和机理。当pH为5.0、磁性Fe_(3)O_(4)/Fe-藻渣碳基功能材料投加量为0.5 g/L时,对Cu^(2+)的去除率(99.88%)与吸附量(19.98 mg/g)均达到最大值;相同pH条件下,磁性Fe_(3)O_(4)/Fe-藻渣碳基功能材料投加量为1.5 g/L时,对Zn^(2+)的去除率(99.73%)达到最大值,此时吸附量为7.979 mg/g;当pH为6.0、藻渣碳基功能材料投加量为0.5 g/L时,对Zn^(2+)的吸附量(19.91 mg/g)达到最大值,此时去除率为82.98%。吸附动力学模型和吸附等温模型拟合参数显示,藻渣碳基功能材料吸附Cu^(2+)和Zn^(2+)的吸附过程更加符合准一级动力学方程和Freundlich模型,其吸附过程为物理作用主导的多分子层吸附。磁性Fe_(3)O_(4)/Fe-藻渣碳基功能材料吸附处理养殖废水中铜和锌的效果显著,可作为高效的吸附剂应用于养殖废水中重金属的去除。

Facile preparation of N-doped corncob-derived carbon nanofiber efficiently encapsulating Fe2O3 nanocrystals towards high ORR electrocatalytic activity

Facile preparation of cost-effective and durable porous carbon-supported non-precious-metal/nitrogen electrocatalysts for oxygen reduction reaction(ORR)is extremely important for promoting the commercialized applications of such catalysts.In this work,the FeCl3-containing porphyrinato iron-based covalent porous polymer(FeCl3·FeP or-CPP)was fabricated in-situ onto porous corncob biomass supports via a simple one-pot method.Subsequent thermal-reduction pyrolysis at 700℃-900℃with CO2 gas as an activating agent resulted in Fe2O3-decorated and N-doped graphitic carbon composite Fe2O3@NC&bio-C with a high degree of graphitization of Fe-involved promotion during pyrolysis(Fe2O3=FeCl3·FePor-CPP derived Fe2O3;NC=N-doped graphene analog;bio-C=the corncob-derived hierarchically porous graphitic biomass carbon framework).The derivedα-Fe2O3 andγ-Fe2O3 nanocrystals(5-10 nm particle diameter)were all immobilized on the N-doped bio-C micro/nanofibers.Notably,the Fe2O3@NC&bio-C obtained at the pyrolysis temperature of 800℃(Fe2O3@NC&bio-C-800),exhibited unusual ORR catalytic efficiency via a 4-electron pathway with the onset and half-wave potentials of 0.96 V and 0.85 V vs.RHE,respectively.In addition,Fe2O3@NC&bio-C-800 also exhibited a high and stable limiting current density of-6.0 mA cm-2,remarkably stability(larger than 91%retention after 10000 s),and good methanol tolerance.The present work represents one of the best results for iron-based biomass material ORR catalysts reported to date.The high ORR activity is attributed to the uniformly distributedα-Fe2O3 andγ-Fe2O3 nanoparticles on the N-enriched carbon matrix with a large specific surface area of 772.6 m^2 g^-1.This facilitates favor faster electron movement and better adsorption of oxygen molecules on the surface of the catalyst.Nevertheless,comparative studies on the structure and ORR catalytic activity of Fe2O3@NC&bioC-800 with Fe2O3@bio-C-800 and NC&bio-C-800 clearly highlight the synergistic effect of the coexisting Fe2O3 nanocrystals,NC,and bio-C on the ORR performance.

Promotional effect for SCR of NO with CO over MnO_(x)-doped Fe_(3)O_(4) nanoparticles derived from metal-organic frameworks

MnO_(x)-Fe_(3)O_(4) nanomaterials were fabricated by using the innovative scheme of pyrolyzing manganesedoped iron-based metal organic framework in inert atmosphere and exhibited extraordinary performance of NO reduction by CO(CO-SCR).Multi-technology characterizations were conducted to ascertain the properties of fabricated materials(e.g.,TGA,XRD,SEM,FT-IR,XPS,BET,H_(2)-TPR and O_(2)-TPD).Moreover,the interaction between reactants and catalysts was ascertained by in situ FT-IR.Experimental results demonstrated that Mn was an ideal promoter for iron oxides,resulting in decrease of crystallite size,improve reducibility property,enhance the mobility and the amount of lattice O^(2-) species,as well as strength the adsorption ability of active NO and CO to form multiple species(e.g.,nitrate and carbonate).The unprecedented enhancement of CO-SCR activity over Mn-Fe nanomaterials follows the Eley-Rideal(E-R)and Langmuir-Hinshelwood(L-H)reaction pathway.

Three-photon-excited fluorescence of Tb^(3+)-doped CaO-Al_2O_3-SiO_2 glass by femtosecond laser irradiation

A near infrared to visible blue, green, and red upconversion luminescence in a Tb^3＋-doped CaO-Al2O3-SiO2 glass was studied, which was excited using 800 nm femtosecond laser irradiation. The upconversion luminescence was attributed to ^5D3→^7F5, ^5D3→^7F4, ^5D3→^7F3, ^5D4→^7F6, ^5D4→^7F5, ^5D4→^7F4, and ^5D4→^7F3 transitions of Tb^3＋. The relationship between upconversion luminescence intensity and the pump power indicated that a three-photon simultaneous absorption process was dominant in this upconversion luminescence. The intense red, green, and blue upconversion luminescence of Tb^3＋-doped CaO-Al2O3-SiO2 glass may be potentially useful in developing three-dimensional display applications.

Fe3C-N-doped carbon modified separator for high performance lithium-sulfur batteries

A new Fe3C-N-doped reduced graphene oxide(Fe3C-N-rGO)prepared by a facile method is used as a separator for high performance lithium-sulfur(Li-S)batteries.The Fe3C-N-rGO is coated on the surface of commercial polypropylene separator(Celgard 2400)close to the sulfur cathode.The special nanotubes are in-situ catalyzed by Fe3C nanoparticles.They could entrap lithium polysulfides(Li PSs)to restrain the shuttle effect and reduce the loss of active material.The battery with the modified separator and sulfur cathode shows an excellent cycle performance.It has a high rate performance,580.5 mAh/g at the high current rate of 4 C relative to 1075 mAh/g at 0.1 C.It also has an initial discharge capacity of 774.8 m Ah/g measured at 0.5 C and remains 721.8 mAh/g after 100 cycles with a high capacity retention of 93.2%.The outstanding performances are notable in recently reports with modified separator.

Preparation and Characterization of Fe^(3+)-doped Nanometer TiO_2 Photocatalysts

Fe^3＋ -doped nanometer TiO2 photocatalysts were prepared by sol-gel technique. TiO2 powders with different Fe^3＋ / Ti^4 ＋ molar ratios ranging from 0. 05% to 25% were synthesized by calcinating the gels in the temperature range of 200-600 ℃ . The effects of the content of iron ions and calcination temperature on the physical properties of the powders and their photocatalytic activities were examined by the photodecorapositon of methyl orange in sunlight. The results show that Fe dopant can decrease the temperature of nanatase-ratile transformation. The ideal photocatalytic property was achieved when the sample with an Fe^3＋ / Ti^4＋ ratio of 20 at% was calcined at about 300 ℃ for an hour, which is superior to that of commercial Degussa P-25. The optimum microstructure of the Fe-doped TiO2 for a high photocatalytic activity in sunlight is consisted of nanatase and ratile.

High efficient oxygen reduction performance of Fe/Fe3C nanoparticles in situ encapsulated in nitrogen-doped carbon via a novel microwave-assisted carbon bath method

Fe-based carbon materials are widely considered promising to replace Pt/C as next-generation electrocatalysts towards oxygen reduction reaction (ORR). However, the preparation of Fe-based carbon materials is still carried out by conventional heating method (CHM). Herein, a novel microwave-assisted carbon bath method (MW-CBM) was proposed, which only took 35 min to synthesize Fe/Fe3C nanoparticles encapsulated in N-doped carbon layers derived from Prussian blue (PB). The catalyst contained large specific surface area and mesoporous structure, abundant Fe-Nx and C–N active sites, unique core-shell structure. Due to the synergistic effects of these features, the as-prepared Fe/Fe3C@NC-2 displayed outstanding ORR activity with onset potential of 0.98 VRHE and halfwave potential of 0.87 VRHE, which were more positive than 20 wt.% Pt/C (0.93 VRHE and 0.82 VRHE). Besides, Fe/Fe3C@NC-2 gave a better stability and methanol tolerance than Pt/C towards ORR in alkaline media, too.

Synthesis of Fe^(3+)-doped Aminated Lignin as A Peroxidase Mimic for Colorimetric Detection of H_(2)O_(2) and Glucose

Peroxidase plays an important role in living systems;however,its storage difficulty and easy inactivation have limited its applications in complex environments.To address these problems,herein,we proposed a method to synthesize peroxidase mimics by amination,carbonization,and Fe^(3+)-doping of industrial alkali lignin.The Fe^(3+)-doped lignin-based peroxidase mimic(Fe-LPM),with active centers of coordination between Fe^(3+)and N atoms,showed higher tolerance to pH value and temperature than natural peroxidase.Using Fe-LPM,10-100 mmol/L of H_(2)O_(2) and glucose could be colorimetrically detected with the lowest detection limits of 80μmol/L and 1.5 mmol/L and visual detection limits of 1.0 mmol/L and 10 mmol/L,respectively.The Fe-LPM maintained peroxidase-like activity after 10 cycles and could even be used for H_(2)O_(2) detection in practical samples.This work not only provides a new approach to synthesize peroxidase mimics using biomass materials but also promotes the high-value utilization of lignin.

Enhanced Water Oxidation Activity on Ni, Co-Doped Fe2O3 （0001） Surface

Fe based oxides are considered as a promising catalyst for the oxygen evolution reaction （OER） due to their low cost and high stability. Here, based on density functional theory calculations, the electrocatalytic behaviors of pure and metal （Ni, Co） doped Fe-terminated Fe2O3（0001） are investigated. The potential-limiting step for OER is determined as the formation of O＊ by dehydrogenating surface hydroxyl and it is suggested that the doping enhances the catalytic activity of Fe2O3（0001） by reducing the free energy change of rate limiting step on doped Ni or Co atom. Especially, the calculated over-potential of Co-doped Fe2O3 （0001） surface is about 0.63 eV on Co site, which is comparable with the theoretical over-potential of 0.56 eV for RuO2.

Studies of Photorefractive Crystals of Double-Doped Ce,Fe:LiNbO_3

In this paper, photorefractive crystals of Ce, Fe:LiNbO 3 are systematically studied. The crystals have been grown by Czochralski method. The samples with different doping concentrations and oxidation/reduction treatments have been fabricated. Their photorefractive properties were experimentally investigated by using two beam coupling. The results show that the photorefractive efficiency depends on the dopant concentration, oxidation/reduction treatment, and light wavelength. The doping mechanism is also discussed here.

Investigation of Mechanism of Co-doped Zn^(2+) and In^(3+) Influence on Optical Properties of Fe∶LiNbO_3

Doping Zn with the concentration of 3mol% and In 2O 3 with different concentrations in Fe∶LiNbO 3, Zn∶In∶ Fe∶ LiNbO 3 crystals were grown. The infrared spectra of the crystals were measured and the mechanism of the OH-, absorption peak shifting was studied. The diffraction efficiency, response time and photoconduction of the crystals were measured. The mechanisms of the photoconduction increasing, diffraction efficiency decreasing and response time shorting for those crystals were studied.

First-principles study on electronic structure, magnetic and dielectric properties of Cr-doped Fe_3C

The first-principles calculations were performed to investigate the electronic structure, magnetic and dielectric properties of Cr-doped Fe_3C, in comparison to those of pure Fe_3C and Cr_3C. The obtained results show that the thermodynamic stability of Crdoped Fe_3C becomes weaker in terms of the larger formation enthalpy, on the contrary, the metallicity and covalency are found to strengthen to some extent. The magnetic moments of Fe_3C, Fe_(11)CrC_4(g), and Fe_(11)CrC_4(s) are respectively 21.36 μB/cell, 16.92 μB/cell, and 17.62 μB/cell, and in Fe_(11)CrC4(g) and Fe_(11)CrC_4(s), the Fe of Wyckoff positions of 8d and 4c is substituted by Cr. The local magnetic moment of Cr at 8d site is larger than that at 4c site in the doped structure, which is opposite to that of Fe. In low frequency band, the permittivity follows the ranking of Fe_(11)Cr C_4(s)>Cr_3C>Fe_(11)Cr C_4(g)>Fe_3C. Once exceeding a certain frequency, the sequence will be broken. Besides the electron transition, the polarization of atoms also makes a contribution to the dielectric properties.

High index of refraction via quantum interference in a three-level system of Er^3＋-doped yttrium aluminium garnet crystal

A simple three-level system is proposed to produce high index of refraction with zero absorption in an Er^3＋-doped yttrium aluminium garnet （YAG） crystal, which is achieved for a probe field between the excited state 4I13/2 and ground state 4I15/2 by adjusting a strong coherent driving field between the upper excited state 4I11/2 and 4I15/2. It is found that the changes of the frequency of the coherent driving field and the concentration of Er^3＋ ions in the YAG crystal can maximize the index of refraction accompanied by vanishing absorption. This result could be useful for the dispersion compensation in fibre communication, laser particle acceleration, high precision magnetometry and so on.

Fabrication and Characterization of Fe-Doped In2O3 Dilute Magnetic Semiconducting Nanowires

Fe-doped In2O3 dilute magnetic semiconducting nanowires are fabricated on A u-deposited Si substrates by the chemical vapor deposition technique. It is confirmed by energy dispersive x-ray spectroscopy （EDS）, x-ray photoelectron spectroscopy （XPS） and Raman spectroscopy that Fe has been successfully doped into lattices of In2O3 nanowires. The EDS measurements reveal a large amount of oxygen vacancies existing in the Fe-doped In2O3 nanowires. The Fe dopant exists as a mixture of Fe2＋ and Fe3＋, as revealed by the XPS. The origin of room-temperature ferromagnetism in Fe-doped In2O3 nanowires is explained by the bound magnetic polaron model.