Meso-macroporous Fe-doped Cu O: Synthesis, characterization, and structurally enhanced adsorption and visible-light photocatalytic activity

The meso-macroporous Fe-doped Cu O was prepared by a simple hydrothermal method combined with post-annealing. The samples were characterized by X-ray powder diffraction(XRD), scanning electron microscopy(SEM), Brunauer-Emmett-Teller N2 adsorption-desorption analyses and UV-vis diffuses reflectance spectroscopy. The Fe-doped Cu O sample shows higher adsorption capacity and photocatalytic activity for xanthate degradation than pure Cu O under visible light irradiation. In addition, the adsorption process is found to fit Langmuir isotherms and pseudo-second-order kinetics. The the first order kinetic Langmuir Hinshelwood model was used to study the reaction kinetics of photocatalytic degradation, and the apparent rate constant( k) was calculated. The value of k for Fe-doped Cu O is 1.5 times that of pure Cu O. The higher photocatalytic activity of Fe-doped Cu O is attributed to higher specific surface area together with stronger visible light absorption.

Phase evolution and room temperature ferroelectric and magnetic properties of Fe-doped BaTiO_3 ceramics

To make the ferroelectric BaTiO3 possess ferromagnetism simultaneously,magnetic Fe was doped into BaTiO3 ceramics at doping levels up to 10%(molar fraction).Both tetragonal and hexagonal phases coexisted in the Fe-doped BaTiO3 ceramics except at 1% doping level.X-ray diffraction analysis indicated that higher doping level of Fe,higher sintering temperature and longer sintering time promoted the formation of hexagonal phases in Fe-doped BaTiO3 ceramics.Ferroelectricity was observed in all samples at room temperature,but it was greatly depressed by Fe doping.Except at doping level of 1%,room-temperature ferromagnetism was observed in the BaTiO3 ceramics.The dependence of the saturation magnetization and coercivities of the Fe-doped BaTiO3 ceramics on doping level was systematically studied.Both the saturation magnetization and magnetic coercivities were found to be dependent on the doping level as well as the fraction of the hexagonal phase in the ceramics.

Synthesis and Room Temperature Ferromagnetism in Fe-Doped CuAlO_2 Semiconductor

The synthesis and characterization of Fe-doped CuA102 semiconductor were reported. The samples were synthesized by a simple and cost effective spin-on technique from solid state reaction of Cu20 and A1203 on sapphire （001） substrate. Appropriate ethyl-cellulose （EC） and terpineol are useful for the formation of Fe-doped CuA102 films. X-ray diffraction （XRD） revealed the growth of pure delafossite CuA102 phase ruled out elemental metallic Fe clusters in all the Fe incorporated CuA102 films. The existence of ferromagnetism at room temperature is evidenced by well-defined hysteresis loops. Specially, the saturation magnetization （Ms） values at room temperature have been monotonously enhanced with the increase of Fe composition from 1% to 5%.

Electron-mediated ferromagnetism in Fe-doped InP:Theory and experiment

We report on the electron-mediated ferromagnetism in Fe-doped InP from both first-principles calculations andexperiments. Theoretically, based on the spin-polarized density functional theory within the Heyd-Scuseria-Ernzerhof （HSE03） approach, we systematically investigate the magnetic properties of Fe-doped InP and predict the existence of electron-mediated ferromagnetism. Experimentally, by diffusing Fe into the n-type InP wafer with thermal annealing at 800 ℃, we observe room-temperature ferromagnetism in InP：Fe, which is in agreement with the theoretical prediction.

Intrinsic relationship between photoluminescence and electrical characteristics in modulation Fe-doped AlGaN/GaN HEMTs

The photoluminescence（PL） and electrical properties of Al GaN/GaN high electron mobility transistors（HEMTs） with different Fe doping concentrations in the GaN buffer layers were studied. It was found that, at low Fe doping concentrations,the introduction of Fe atoms can result in a downward shift of the Fermi level in the GaN buffer layer, since the Fe atoms substitute Ga and introduce an FeGa^3＋/2＋ acceptor level. This results in a decrease in the yellow luminescence（YL） emission intensity accompanied by the appearance of an infrared（IR） emission, and a decrease in the off-state buffer leakage current（BLC）. However, a further increase in the Fe doping concentration will conversely result in the upward shift of the Fermi level due to the incorporation of O donors under the large flow rate of the Fe source. This results in an increased YL emission intensity accompanied by a decrease in the IR emission intensity, and an increase in the BLC. The intrinsic relationship between the PL and BLC characteristics is expected to provide a simple and effective method to understand the variation of the electrical characteristic in the modulation Fe-doped HEMTs by optical measurements.

NiCo-LDH材料的形貌分析与电化学性能研究

采用一步水热法在泡沫镍上合成镍钴层状双金属氢氧化物(NiCo-LDH)电极材料,用扫描电镜分析电极材料的微观形貌,X射线衍射仪分析电极材料的物相,并在不同扫描速率以及不同电流密度下NiCo-LDH纳米材料进行了电化学性能测试。结果表明:随着尿素含量的增加,NiCo-LDH的形貌由六角片状、草丛状,最后形成片层上带有针状形貌。扫描速率为10 mV·s^(-1)时,在CV曲线中可以清晰地看到氧化还原峰。电极在0.30~0.35V之间的充放电曲线出现对称的充放电平台,说明其充放电容量和充放电时间均较优,该复合材料的电容性能良好。

MnS@NiCo-LDH复合电极材料超级电容性能研究

Mn S作为一种具有宽带隙的半导体材料,在超级电容器领域受到广泛关注。合理设计异质结构复合电极材料是解决超级电容器储能性能差的可行方法。采用水热结合电沉积技术制备了Mn S@Ni Co-LDH薄膜复合电极,并对其结构及电化学性能进行测试分析。MnS@NiCo-LDH薄膜复合电极具有片状多孔隙分层次结构,在1 A/g电流密度下具有高达2 418 F/g的比电容、高的倍率性能(80.89%)及良好的循环稳定性(1 700次循环后电容保持率为79.6%)。结果表明,所设计制备的MnS@NiCo-LDH薄膜复合电极具有满足先进储能器件要求的巨大潜力,为设计其他复合电极材料提供了新思路。

Room Temperature Synthesis of Vertically Aligned Amorphous Ultrathin NiCo-LDH Nanosheets Bifunctional Flexible Supercapacitor Electrodes

Developing a simple scalable method to fabricate electrodes with high capacity and wide voltage range is desired for the real use of electrochemical supercapacitors.Herein,we synthesized amorphous NiCo-LDH nanosheets vertically aligned on activated carbon cloth substrate,which was in situ transformed from Co-metal-organic framework materials nano-columns by a simple ion exchange process at room temperature.Due to the amorphous and vertically aligned ultrathin structure of NiCo-LDH,the NiCo-LDH/activated carbon cloth composites present high areal capacities of 3770 and 1480 mF cm^(-2)as cathode and anode at 2 mA cm^(-2),and 79.5%and 80%capacity have been preserved at 50 mA cm^(-2).In the meantime,they all showed excellent cycling performance with negligible change after>10000 cycles.By fabricating them into an asymmetric supercapacitor,the device achieves high energy densities(5.61 mWh cm^(-2)and 0.352 mW cm^(-3)).This work provides an innovative strategy for simplifying the design of supercapacitors as well as providing a new understanding of improving the rate capabilities/cycling stability of NiCo-LDH materials.

Photocatalytic Degradation of NOx Under Visible Light Irradiation Using Fe-Doped Titanium Dioxide

In order to utilize visible light in photocatalytic conversion of NOx, Fe atoms were doped in commercially available photocatalytic TiO2 powders by impregnating method. The crystal phase of TiO2 was not changed after calcination process. Analysis by both X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) indicated that Fe atoms were incorporated in TiO2 as Ti-O-Fe linkages. One significant shift of the absorption edge to a lower energy and a higher absorption in the visible light region were observed. The Fe-doped TiO2 powder exhibited photocatalytic activity for the degradation of NOx under visible light irradiation. The sample mixed with 0.2 at% Fe3+and calcined at 600 ℃ showed the best photocatalytic activity.

Detection of Fe 3d electronic states in the valence band and magnetic properties of Fe-doped ZnO film

Fe-doped ZnO film has been grown by laser molecular beam epitaxy（L-MBE） and structurally characterized by X-ray diffraction（XRD） and scanning electron microscopy（SEM）,all of which reveal the high quality of the film.No secondary phase was detected.Resonant photoemission spectroscopy（RPES） with photon energies around the Fe 2p-3d absorption edge is performed to detect the electronic structure in the valence band.A strong resonant effect at a photon energy of 710 eV is observed.Fe3＋ is the only valence state of Fe ions in the film and the Fe 3d electronic states are concentrated at binding energies of about 3.8 eV and 7 eV～8 eV.There are no electronic states related to Fe near the Fermi level.Magnetic measurements reveal a typical superparamagnetic property at room temperature.The absence of electronic states related to Fe near the Fermi level and the high quality of the film,with few defects,provide little support to ferromagnetism.

Fe-doped ZnS film fabricated by electron beam evaporation and its application as saturable absorber for Er:ZBLAN fiber laser

High-quality Fe-doped Zn S films have been fabricated by electron beam evaporation.After the doping,the fabricated films still maintain the preferential crystalline orientation and phase purity of the host Zn S.According to the observation of surface morphology,the root mean-square roughness of the samples increases slightly with the increase of doping content.All of the prepared samples are in cubic zinc blende structure of Zn S.Transmission spectrum confirms a more obvious dip near 3μm with higher dopant concentration and it can be attributed to the typical^(5)E→^(5)T_(2)transition of Fe^(2+).Fe-doped Zn S film is also successfully used for Q-switched Er:ZBLAN fiber laser.

Self-template synthesis of hollow Fe-doped CoP prisms with enhanced oxygen evolution reaction activity

The development of efficient, durable and low cost electrocatalysts is crucial but extremely challenging for the oxygen evolution reaction (OER). Herein, we develop a self-template strategy to synthesize hollow Fe-doped CoP prisms (Fe-CoP) via ion exchange of cobalt acetate hydroxide with [Fe(CN)_(6)]^(3-) and phosphorization-induced transformation of CoFe-PBA (Co/Fe-containing prussian blue analogue) prisms in N2 atmosphere. The obtained Fe-CoP not only inherits the hollow prism-like morphology of CoFe-PBA, but also forms rich mesoporous channel. The Fe-CoP prisms exhibit extraordinary OER performances in 1.0 M KOH, with a low overpotential of 236 mV to deliver a current density of 10 mA cm^(−2) and a low Tafel slope of 32.9 mV dec^(–1). Moreover, the presented electrocatalyst shows good long-term operating durability and activity. The XPS and TEM analysis confirm that Fe-CoP has undergone surface reconstruction in the process of electrocatalytic OER, and the in situ formed oxides and oxyhydroxides are the real active species to boost OER. This work provides a promising pathway to the design and synthesis of efficient and robust electrocatalysts with hierarchical hollow structure for boosting OER.

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.

Optimization of Conditions for the Photocatalytic Degradation of EDTA in Aqueous Solution with Fe-Doped Titanium Dioxide

The conditions for photocatalytic degradation of ethylenediaminetetraacetic acid (EDTA) in aqueous solution with Fe-doped titanium dioxide (TiO2) were optimized. The degradation efficiencies with Fe-doped TiO2 were better, compared with those obtained with bare TiO2 and Pt-doped TiO2. The effect of various experimental factors, such as photocatalytic dosage, temperature, solution pH and light intensity on the photocatalytic degradation of EDTA by Fe-doped TiO2 was investigated. The photocatalytic degradation treatment for the wastewater containing EDTA is simple, easy handling and low cost.

偏钒酸根掺杂的NiCo-LDH电极的制备及性能研究

超级电容器是近年来电化学储能器件研发的热点之一,其电极材料对其性能起决定性作用。为了合成具有优异超电容性能的NiCo基二维层状双氢氧化物(LDH)电极材料,首先通过一步水热法在泡沫镍网表面制备NiCo-LDH纳米阵列;然后在水-乙二醇体系下,通过二次溶剂热反应,制备偏钒酸根掺杂的NiCo-LDH纳米阵列;最后,通过碱转化得到性能优异的电极材料。用此电极与活性碳组装成全固态不对称超级电容器件,在电压为0~1.8 V、功率密度为9 mW/cm^(2)时,器件的能量密度达0.416 mW·h/cm^(2),且具有良好的循环稳定性。

NiCo-LDH与醋糟衍生碳复合材料的制备及其在超级电容器中的应用

以废弃醋糟为碳源,通过氢氧化钾活化制备多孔性、高比表面积的醋糟衍生碳,再采用水热法制备出双金属氢氧化物/醋糟衍生碳(NiCo-LDH/C)复合电极材料。利用循环伏安(CV)、恒流充放电(GCD)、XRD以及场发射扫描电镜(SEM)等测试方法表征复合材料的形貌和性能。结果表明,在10 A/g的电流密度下该材料的比电容可达915 F/g;1000次充放电后电容量仍保持82.5%。NiCo-LDH/C复合材料在能量存储领域具有巨大应用潜力。

NiCo-LDH电极材料的合成及其超级电容性能综合实验设计

本实验采用水热法及不同沉淀剂,在泡沫镍表面原位生长出不同形貌的镍钴层状双金属氢氧化物(NiCo-LDHs)电极材料,通过X射线衍射仪和扫描电子显微镜对样品进行物相及形貌表征,利用电化学工作站对电极材料的超级电容性能进行评价。实验结果表明,在其他反应条件相同情况下,以六亚甲基四胺(HMT)和尿素作为沉淀剂,所得产物形貌分别为纳米片和纳米线,而NiCo-LDH纳米片的超级电容性能优于纳米线。该实验设计简单,涵盖纳米材料合成、表征及电化学性能评价等诸多知识点,有助于学生理解纳米材料形貌与性能间的关系,提升学生的科研意识和综合实践能力。

超级电容器用NiCo-LDH电极材料研究进展

镍钴层状双金属氢氧化物(NiCo-LDH)具有理论比电容大、成本低等优势,作为超级电容器电极材料得到广泛研究,但导电性能和电化学性能较差,限制了实际应用。简要介绍NiCo-LDH电极材料的储能原理、电化学性能影响因素(如比表面积、孔径和导电性等)和制备方法,其中包括水热法(溶剂热法)、微波法、电化学沉积法、化学共沉淀法和牺牲模板法等。重点介绍NiCo-LDH电极材料的改性研究(如改变形貌、制备复合材料等),并对研究方向进行展望。

三维花状NiCo-LDHs对染料废水的吸附性能研究

层状双金属氢氧化物(LDHs)材料对阴离子废水具有优异的吸附作用。以三乙醇胺为碱源,通过水热法合成了3种花簇状NiCo-LDHs材料,并讨论了3种材料对甲基橙(MO)废水的吸附性能,结果表明,3种材料对MO具有快速吸附能力,最大吸附量分别为1001.64、1142.07、1003.18 mg/g。吸附过程符合准二级动力学方程,吸附等温线符合Langmuir方程,表明了该吸附过程为单层吸附。Ni Co-LDHs可以作为一种高效的吸附材料,去除染料废水中的MO。

NiCo-LDH/Ti3C2 MXene hybrid materials for lithium ion battery with high-rate capability and long cycle life

Nickel/cobalt-layered double hydroxides(Ni Co-LDH) have been attracted increasing interest in the applications of anode materials for lithium ion battery(LIB), but the low cycle stability and rate performance are still limited its practice applications. To achieve high performance LIB, the surface-confined strategy has been applied to design and fabricate a new anode material of NiCo-LDH nanosheet anchored on the surface of Ti3C2 MXene(Ni Co-LDH/Ti3C2). The ultra-thin, bended and wrinkled α-phase crystal with an interlayer spacing of 8.1 ? can arrange on the conductive substrates Ti3C2 MXene directly, resulting in high electrolyte diffusion ability and low internal resistance. Furthermore, chemical bond interactions between the highly conductive Ti3C2 MXene and Ni Co-LDH nanosheets can greatly increase the ion and electron transport and reduce the volume expansion of NiCo-LDH during Li ion intercalation. As expected,the discharge capacity of 562 m Ah g-1 at 5.0 A g-1 for 800 cycles without degradation can be achieved,rate capability and cycle performance are better than that of NiCo-LDH(~100 mAh g-1). Furthermore, the density function theory(DFT) calculations were performed to demonstrate that Ni Co-LDH/Ti3C2 system can be used as a highly desirable and promising anode material for lithium ion battery.