Preparation of Al2O3 nanowires on 7YSZ thermal barrier coatings against CMAS corrosion

The commonly-employed material for thermal barrier coatings(TBCs)is 7 wt.%Y2O3 ZrO2(7YSZ),generally deposited by electron beam-physical vapor deposition(EB-PVD).Due to the increasing demand for higher operating temperature in aero-derivative gas turbines,a lot of effort has been made to prevent the premature failure of columnar 7YSZ TBCs,which is induced by the microstructure degradation,sintering and spallation after the deposition of infiltrated siliceous mineral(consisting of calcium magnesium aluminum silicate(CaO MgO Al2O3 SiO2,i.e.,CMAS)).A new method called Al-modification for columnar 7YSZ TBCs against CMAS corrosion was present.The Al film was magnetron-sputtered on the surface of the columnar 7YSZ TBCs,followed by performing vacuum heat treatment of the Al-deposited TBCs.During the heat treatment,the molten Al reacted with ZrO2 to formα-Al2O3 overlay that effectively hindered CMAS infiltration.Moreover,the Al film could evaporate and re-nucleate,leading to the generation of Al2O3 nanowires,which further restrained the moving of molten CMAS.

Realizing super-long Cu_2O nanowires arrays for high-efficient water splitting applications with a convenient approach

Nanowire(NW) structures is an alternative candidate for constructing the next generation photoelectrochemical water splitting system, due to the outstanding optical and electrical properties. NW photoelectrodes comparing to traditional semiconductor photoelectrodes shows the comparatively shorter transfer distance of photo-induced carriers and the increase amount of the surface reaction sites, which is beneficial for lowering the recombination probability of charge carriers and improving their photoelectrochemical(PEC) performances. Here, we demonstrate for the first time that super-long Cu_2O NWs, more than 4.5 μm,with highly efficient water splitting performance, were synthesized using a cost-effective anodic alumina oxide(AAO) template method. In comparison with the photocathode with planar Cu_2O films, the photocathode with Cu_2O NWs demonstrates a significant enhancement in photocurrent, from –1.00 to –2.75 mA/cm^2 at –0.8 V versus Ag/AgCl. After optimization of the photoelectrochemical electrode through depositing Pt NPs with atomic layer deposition(ALD) technology on the Cu_2O NWs, the plateau of photocurrent has been enlarged to –7 mA/cm^2 with the external quantum yield up to 34% at 410 nm. This study suggests that the photoelectrode based on Cu_2O NWs is a hopeful system for establishing high-efficiency water splitting system under visible light.

Porous NiCo_2O_4 nanowires supported on carbon cloth for flexible asymmetric supercapacitor with high energy density

Recently, binary metal oxides have been considerably researched for energy storage since it can provide higher electrical conductivity and electrochemical activity than single components. Besides, rational arrays structure design can effectively enhance the utilization of active material. In this article, we synthesis a porous NiCo_2O_4 nanowires arrays, which were intimate contact with flexible carbon cloth（CC）by a facile hydrothermal reaction and calcination treatment. The rational array structures of NiCo_2O_4 facilitate the diffusion of electrolyte and effectively increase the utilization of active material. The asobtained NiCo_2O_4@CC electrode exhibits a high capacitance of 1183 mF cm^（-2） and an outstanding capacitance retention of 90.4% after 3000 cycles. Furthermore, a flexible asymmetric supercapacitor（ASC）using NiCo_2O_4@CC as positive electrode and activated carbon cloth（ACC） as negative electrode was fabricated, which delivers a large capacitance of 750 mF cm^（-2）（12.5 F cm^（-3））, a high energy density of 0.24 mWh cm^（-2）（3.91 mWh cm^（-3））, as well as excellent cycle stability under different bending states.These remarkable results suggest that as-assembled NiCo_2O_4@CC//ACC ASC is a promising candidate in flexible energy storage applications.

Synthesis and characterization of β-Ga_2O_3@GaN nanowires

In this work, we prepared the β-Ga_2O_3@GaN nanowires(NWs) by oxidizing GaN NWs. High-quality hexagonal wurtzite GaN NWs were achieved and the conversion from GaN to β-Ga_2O_3 was confirmed by x-ray diffraction, Raman spectroscopy and transmission electron microscopy. The effect of the oxidation temperature and time on the oxidation degree of GaN NWs was investigated systematically. The oxidation rate of GaN NWs was estimated at different temperatures.

Facile Preparation of Mn_2O_3 Nanowires by Thermal Decomposition of MnCO_3

Mn2O3 nanowires with diameters of about 130 nm and lengths up to tens of micrometers were synthesized by the thermal decomposition of MnCO3 precursors. It was identified that the growth of the cubic Mn2O nanowires was preferential along the [001] direction. The intermediate stage containing melting state and the particles of manganese oxide played an important role for the formation of Mn2O3 with one-dimensional structure. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used to characterize the morphology and crystal structure of the precursors and final products. Thermogravimetry analysis was also carried out to find the mechanism for the formation of Mn2O3 nanowires. The growth of the nanowires was proposed to be dominated by the conventional melt-growth mechanism.

Comparable Studies of Adsorption and Magnetic Properties of Ferrite MnFe_2O_4 Nanoparticles,Porous Bulks and Nanowires

The spinel ferrites MnFe2O4 nanowires were synthesized by hydrothermal route,porous MnFe2O4 and nanoparticles morphologies were synthesized by sol-gel method with egg white.The structures,morphologies,magnetic properties and adsorption properties of these obtained ferrites with different morphologies were studied contrastively.Results show that the obtained samples exhibit ferromagnetic properties.This realizes convenient magnetic separation from solution when they are used in the treatment of organic dyes wastewater.However,the contrastive studies show that the saturation magnetizations（Ms） of MnFe2O4 with different morphologies are different and the Ms follows the order：Ms（porous）〈Ms（nanoparticles）〈Ms（nanowires）.In addition,the adsorptions of methylene blue（MB） onto these ferrites depend on ferrites＇ morphologies seriously.The adsorption rate of MB on the porous MnFe2O4 is much higher than those onto the other two samples because the porous structure can provide high efficient mass transport through the pores.

An improved sensitivity non-enzymatic ascorbic acid sensor based on a Ag_2O nanowire modified Ag electrode

In this paper, the Ag2O nanowires had been prepared and applied for the fabrication of ascorbic acid sensors with high enhanced sensitivity by using self-assembly technology. The structures and morphologies of Ag2O nanowires were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The direct electrocatalytic oxidation of ascorbic acid in alkaline medium at Ag2O nanowires modified electrodes had been investigated in detail and the condition for determination of ascorbic acid was optimized, such as support-electrolyte, pH and scan speed. The oxidation peak current changed linearly with the concentration of ascorbic acid over the range from 2.0×10-8 mol/L to 1.0 mmol/L, and the detection limit can reach 1.0×10-8mol/L. Compared to a bare Ag electrode, a substantial decrease in the overvoltage of the ascorbic acid oxidation was observed at the Ag nanowires electrodes with oxidation starting at ca. 0.7V vs. Ag/AgCl (saturated KCl). The Ag2O nanowires modified electrode allows highly sensitive, low working potential, stable, and fast amperometric sensing of ascorbic acid, thus is promising for the future development of non-enzymatic ascorbic acid sensors.

Thermal Stability of Fe_2O_3 Nanowires

The thermal stability of α-Fe203 and γ-Fe2O3 nanowires was studied by post annealing the samples at different temperatures. Before and after annealing, the samples were characterized by X-ray diffraction and scanning electron microscopy. The α-Fe2O3 nanowires are stable at the temperatures up to 600℃, and the crystalline structure becomes more perfect after annealing. This behavior supplies a way to improve the quality of the α-Fe2O3 nanowires. The γ-Fe2O3 nanowires become unstable when annealed at 350℃. Raman spectra of both nanowires have been measured, which also indicate that the γ-Fe203 nanowires are transformed into α-Fe2O3 under the strong laser beam.

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.

High Purity and Large-scale Preparation of β-Ga_2O_3 Nanowires and Nanosheets by CVD and Their Raman and Photoluminescence Characteristics

Ga2O3 nano-structures, nanowires and nanosheets are produced on Au pre-coated(111) silicon substrates with chemical vapor deposition(CVD) technique. By evaporating pure Ga powder in the H2O atmosphere under ambient pressure the large-scale preparation of β-Ga2O3 with monoclinic crystalline structure is achieved. The crystalline structures and morphologies of produced Ga2O3 nano-structures are characterized by means of scanning electron microscope(SEM), X-ray diffraction(XRD), selected area electron diffraction(SAED) and transmission electron microscope(TEM). Raman spectrum reveals the typical vibration modes of Ga2O3. The vibration mode shifts corresponding to Ga2O3 nano-structures are not found. Two distinguish photoluminescence(PL) emissions are found at about 399 nm and 469 nm owing to the VO-VGa excitation and VO-VGa-O excitation, respectively. The growth mechanisms of Ga2O3 nanowires and nanosheets are discussed with vapor-liquid-solid(VLS) and vapor-solid(VS) mechanisms.

Cu_(2)O纳米线阵列的制备与表征

Cu_(2)O纳米线阵列既保留了纳米线长径比高、比表面积大等优点,又具有规模效应及协同效应,在气敏、光伏等领域具有广阔的应用前景。以泡沫铜为基体,通过化学法制备Cu(OH)_(2)纳米线阵列为前驱体,并在N_(2)气氛中采用两步加热法制备Cu_(2)O纳米线阵列,利用X射线衍射(XRD)、扫描电镜(SEM)对Cu_(2)O纳米线阵列结构进行表征。结果表明:只需控制、优化Cu基底的曲率半径和弧度,就能制备出Cu_(2)O纳米线阵列,这为制备Cu_(2)O纳米线阵列薄膜提供了新的思路。

累托石/δ-MnO_2颗粒吸附剂的制备及其应用研究

以海藻酸钠为包埋剂,氯化钙为交联剂,包埋制备了钠基累托石/δ型二氧化锰球形颗粒吸附剂(Na-REC/δ-Mn O_2)。采用傅里叶红外光谱(FTIR)、X射线衍射仪(XRD)和扫描电镜(SEM)对球形颗粒吸附剂进行了表征。研究了海藻酸钠(SA)、钠基累托石/δ型二氧化锰粉末(Na-REC/δ-Mn O_2-F)添加量和氯化钙质量浓度对吸附剂成球性能的影响。探讨了Na-REC/δ-Mn O_2添加量,溶液p H值和吸附时间对吸附结晶紫的影响。结果表明,当添加聚乙二醇2 g,海藻酸钠0.6 g,钠基累托石/δ型二氧化锰粉末3 g,氯化钙质量浓度为1%时,球形颗粒吸附剂的散失率最低,吸附性能最好。在Na-REC/δ-Mn O_2的添加量为30 g/L,溶液p H=7,吸附时间为100 min时,Na-REC/δ-Mn O_2对结晶紫的最大吸附量为122.56 mg/g,吸附过程符合Lagergren准二级动力学方程,膜扩散过程为该吸附过程的控制步骤。球形颗粒吸附剂具有较好的重复使用性能,最优条件下重复使用5次时,对结晶紫的吸附率为61.34%。

水热氧化法制备γ-Mn_2O_3

用水热氧化法制备出γＭｎ２Ｏ３粉末，并在不同温度下进行烧结．采用ＸＲＤ，ＴＥＭ，ＸＰＳ，ＩＲ及紫外分光光度法等表征产物．结果表明，未烧结产物即为单相纳米晶，大部分近似球形，有轻微团聚．产物于空气中１００～５５０℃范围内烧结时热稳定性好．随烧结温度的升高粉末的平均粒子尺寸增大，产物中锰以Ｍｎ（Ⅲ）状态存在．

β-MnO_2和α-Mn_2O_3纳米棒的自牺牲模板法制备、表征和应用

在150℃下,仅以高锰酸钾溶液和无水乙醇为原料,通过水热反应合成前驱体γ-Mn OOH纳米棒.以γ-Mn OOH纳米棒为自牺牲模板,分别在350和600℃下煅烧90 min,制备出高纯度的β-Mn O2和α-Mn2O3纳米棒.采用X射线粉末衍射（XRD）、扫描电子显微镜（SEM）及热重分析（TGA）等对所制备的样品进行表征.结果表明,前驱物γ-Mn OOH为高纯度的纳米棒状晶体,直径约100-300 nm,长度可达数微米,且终产物β-Mn O2和α-Mn2O3均具有较高的纯度,也很好地保持了前驱物的纳米棒状结构.以二者为锰源,通过固相反应合成出尖晶石Li Mn2O4正极材料.当充放电倍率为0.5 C时,其首次放电比容量分别可达到120.4和123.9 m A·h/g,而且表现出良好的循环性能和倍率性能。

溶胶—凝胶法合成棒状β-Mn_2V_2O_7锂电池负极材料

采用溶胶—凝胶法成功制备了棒状β-Mn2V2O7锂电池负极材料。结果表明,合成的β-Mn2V2O7的纯度高、形貌规整有序,首次放电比容量达590mAh/g,40圈内容量较第二圈基本没有衰减。

有机前驱体制备纳米γ-Mn_2O_3块体的研究

以氯化锰、甘油与六次甲基四胺为原料进行发泡制得锰酸酯前驱物,经高温热分解前驱物制得了纳米γ-Mn2O3块体,使用XRD和SEM对块体进行了表征。结果表明:发泡有机前驱物在450℃马弗炉中焙烧2.0h得纳米γ-Mn2O3块体,块体由200nm左右粒子堆积构成二级粒子,二级粒子由粒径为8.3nm的纳米粒子构成。

Structures and magnetic anisotropy of β-Mn_2V_2O_7 crystals synthesized by the molten salt method

β-Mn2V2O7 crystals with strip shape are successfully prepared by the molten salt method in a closed crucible, and are characterized by x-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, selected area of electron diffraction （SAED） and high-resolution transmission electron microscopy （HRTEM）. The results indicate that the sample is of the β-Mn2V2O7 crystal with monoclinic symmetry, level natural cleavage facets and directional growth. Magnetic properties are measured by vibration sample magnetometry （VSM） at room temperature, and the magnetic hysteresis loop indicates that the β-Mn2V2O7 has anti-ferromagnetic properties with low coercive force and remnant magnetization. The magnetic measurement results in different directions exhibit that the β-Mn2V2O7 has magnetic anisotropy, which is due to the fact that the magnetic interaction energy of the β-Mn2V2O7 is lowest only when the electron configuration is in a certain direction.

纳米二氧化锰负载钴锰催化K_2S_2O_8/NaHCO_3降解甲基橙

为了去除碱性水溶液中的染料,采用纳米二氧化锰负载钴锰(Co(Ⅱ)-Mn(Ⅱ)-MnO_2)催化K_2S_2O_8/NaHCO_3氧化降解染料。对Co(Ⅱ)-Mn(Ⅱ)-MnO_2催化剂进行形貌和结构表征。考察了溶液初始pH值、反应温度、催化剂投加量、甲基橙(MO)、过硫酸钾摩尔比及碳酸氢钠浓度等因素对Co(Ⅱ)-Mn(Ⅱ)-MnO_2催化氧化MO的影响,并对MO氧化过程结构变化进行分析。实验结果表明:在优化条件下Co(Ⅱ)-Mn(Ⅱ)-MnO_2催化MO(40mg/L)的降解率达到82.61%,MO降解反应动力学为一级反应。该体系适合处理中性和弱碱性MO废水。

铜(Ⅱ)-锰(Ⅱ)-氧化锌协同催化H_2O_2-HCO_3^-体系降解阳离子蓝X-GRRL

以硝酸铜和硫酸锰为原料,利用Zn O对Cu(Ⅱ)、Mn(Ⅱ)的吸附作用制备了Cu(Ⅱ)-Mn(Ⅱ)-Zn O(CMZ)非均相催化剂。运用X射线光电子能谱(XPS)和原子吸收分光光度计(AAS)对产物结构和组成进行表征。考察了溶液初始p H、不同金属离子催化剂及用量对催化性能的影响,探讨了降解反应机制。通过监测反应过程中IR和UV谱的变化,对染料降解过程进行初步分析。研究结果表明,在碱性条件下,CMZ非均相催化氧化阳离子蓝X-GRRL效果很好,催化剂可循环使用3次;适合处理阳离子蓝X-GRRL染料废水。

Charge storage mechanism of MOF-derived Mn2O3 as high performance cathode of aqueous zinc-ion batteries

Aqueous Zinc-ion batteries(ZIB) are attracting immense attention because of their merits of excellent safety and quite cheap properties compared with lithium-ion batteries(LIB).Manganese oxide is one of the most important cathode materials of ZIB.In this paper,α-Mn2O3 used as cathode of ZIB is synthesized via Metal-Organic Framework(MOF)-derived method,which delivers a high specific capacity of225 mAh g^(-1) at 0.05 A g^(-1) and 92.7 mAh g^(-1) after 1700 cycles at 2 A g^(-1).The charge storage mechanism of α-Mn2O3 cathode is found to greatly depend on the discharge current density.At lower current density discharging,the H+ and Zn2+ are successively intercalated into the α-Mn2O3 before and after the "turning point" of discharge voltage and their discharging products present obviously different morphologies changing from flower-like to large plate-like products.At a higher current density,the low-voltage plateau after the turning point disappears due to the decrease of amount of Zn2+ intercalation and the H+intercalation is dominated in α-Mn2 O3.This study provides significant understanding for future design and research of high-performance Mn-based cathodes of ZIB.