Water oxidation electrocatalyzed by an efficient Mn3O4/CoSe2 nanocomposite

The design of efficient, cheap, and abundant oxygen evolution reaction (OER) catalysts is crucial to the development of sustainable energy sources for powering fuel cells. We describe here a novel Mn(3)O(4)/CoSe(2) hybrid which could be a promising candidate for such electrocatalysts. Possibly due to the synergetic chemical coupling effects between Mn(3)O(4) and CoSe(2), the constructed hybrid displayed superior OER catalytic performance relative to its parent CoSe(2)/DETA nanobelts. Notably, such earth-abundant cobalt (Co)-based catalyst afforded a current density of 10 mA cm(-2) at a small overpotential of ~0.45 V and a small Tafel slope down to 49 mV/decade, comparable to the best performance of the well-investigated cobalt oxides. Moreover, this Mn(3)O(4)/CoSe(2) hybrid shows good stability in 0.1 M KOH electrolyte, which is highly required to a promising OER electrocatalyst.     

Hybrid nanonet/nanoflake NiCo2O4 electrodes with an ultrahigh surface area for supercapacitors

An integrated electrode consisting of hybrid nanonet/nanoflake NiCo₂O₄ grown on stainless steel mesh substrates exhibits a high specific capacitance while maintaining high-rate capability and good cycling stability. The specific capacitance reaches a maximum of 911 F g^?1 at a current density of 10 A g^?1, which can still retain 864 F g^?1 (94.8 % retention) after 10,000 cycles. These much-improved electrochemical performances are attributed to the unique architecture of NiCo₂O₄ electrode. The interconnected nanonet NiCo₂O₄ with an ultrahigh surface area significantly facilitates the rapid ion/electron transport and guarantees good mechanical adhesion, while the ultrathin nanoflakes further extend the active sites for fast redox reactions for efficient energy storage. Figure

Hybrid nanonet/nanoflake NiCo₂O₄ grown on stainless steel mesh exhibits superior capacitive performance and long-life stability as an integrated electrode for high-performance supercapacitors.     

Enhanced photocatalytic performance of N-doped RGO-FeWO4/Fe3O4 ternary nanocomposite in environmental applications

Nitrogen doped RGO- FeWO₄/Fe₃O₄ (NRGO-FeWO₄/Fe₃O₄) ternary nanocomposite was synthesized by rapid single step microwave irradiation approach using iron acetate, ammonium tungstate and graphene oxide as precursors. The synthesized materials were thoroughly characterized by diffraction, microscopic and spectroscopic techniques. The materials were tested for their catalytic efficiency in photo degradation of Methylene Blue (MB) dye and in reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). MB was mineralized within 100 minutes of visible light irradiation time in the presence of the ternary composite, apart from excellent stability and efficiency even after 10 consecutive cycles. The composite also had the capacity to convert 4-NP into 4-AP within 45 seconds and showed very good catalytic activity even after 20 cycles. The results revealed that ternary composite has way more efficiency than the component materials and can act as a promising catalyst for various environmental and engineering applications.     

MoO3/TiO2 和WO3/TiO2 光催化分子氧氧化甲烷的活性

以Ｓｏｌ－Ｇｅｌ法制备的、表面积和孔径相近的含水ＭｏＯ３／ＴｉＯ２、ＷＯ３／ＴｉＯ２为催化剂,光催化分子氧氧化甲烷,初步研究表明,催化剂的活性高于ＴｉＯ２,且有少量的甲醇生成。     

Preparation of rGO,Fe2O3, and Fe2O3/rGO for the catalytic thermal decomposition of microspherical TKX-50

Journal of Thermal Analysis and Calorimetry - Dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50), a promising energetic materials (EMs), has attracted intensive attention in...     

Synthesis and properties of magnetically separable Fe3O4/TiO2/Bi2O3 photocatalysts

The Fe₃O₄/TiO₂/Bi₂O₃ composites were synthesized by a sol–gel method and used as improved photocatalysts for the degradation of methyl orange (MO) under simulated sunlight at room temperature. The as-prepared Fe₃O₄/TiO₂/Bi₂O₃ composites were characterized by X-ray diffraction, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and diffuse reflectance spectroscopy (DRS). TEM analysis reveals that the composite has a core–shell structure and diameters of Fe₃O₄ core is about 200 nm. DRS results reveal that all composites showed red shift in optical absorption. TiO₂, Fe₃O₄, and Bi₂O₃ exist mainly as separate phases in the Fe₃O₄/TiO₂/Bi₂O₃ composites based on XPS analysis. The photocatalytic degradation of MO with the prepared photocatalysts was studied under simulated sunlight illumination. Photocatalytic reactivity test indicated that the removal efficiency of MO with the Fe₃O₄/TiO₂/Bi₂O₃ photocatalyst was higher than that of pure TiO₂ and Fe₃O₄/TiO₂. Recovery rate of Fe₃O₄/TiO₂/Bi₂O₃ photocatalysts achieved 80 % after five times reuse.     

TiO2包覆对LiCO1/3Ni1/3Mn1/3O2材料的表面改性

为了提高材料LiCo1/3Ni1/3MnO2的循环件能,采用浸渍-水解法对其进行TiO2包覆.用X射线衍射(XRD)、电化学交流阻抗谱(EIS)、电感耦合等离子体发射光谱(ICP-OES)和恒流允放电测试研究包覆材料的结构和电化学性能.TiO2仅在材料表面形成包覆层,并未改变材料的结构.TiO2包覆能提高材料LiCo1/3Ni1/3Mn1/3O2的倍率性能和循环性能,TiO2包覆后的材料在5.0C(1.0C=160 mA·g-1)下的放电容量达到0.2C下的66.0%,而包覆前的材料在5.0C下的放电容量仅为其0.2C下的31.5%.包覆后的材料在2.0C下循环12周后的容最没有衰减,而未包覆的材料容量保持率仅为94.4%.EIS测试表明包覆材料性能的提高是由于循环过程中材料的界面稳定性得到了提高.循环后材料的XRD和ICP-OES测试表明,包覆层能提高材料LiCo1/3Ni1/3Mn1/3O2的结构稳定性.     

In3+-doped TiO2 and TiO2/In2S3 nanocomposite for photocatalytic and stoichiometric degradations

A novel In(3+)-doped TiO(2) and TiO(2)/In(2)S(3) nanocomposites for photocatalytic degradation of environmental pollutants and stoichiometric degradation of warfare agents were prepared by a homogeneous hydrolysis with urea and thioacetamide, respectively. The prepared samples series TiInTAA were annealed at 600°C. The prepared samples were characterized by X-ray powder diffraction, IR spectroscopy, Raman spectroscopy, specific surface area (BET) and porosity determination. The method of UV-Vis diffuse reflectance spectroscopy was employed to estimate band-gap energies. The photocatalytic activity (PCA) was tested by degradation of Orange dye, whereas stoichiometric activity was studied by degradation of sulfur mustard. Incorporation of In(3+) into titania lattice increases PCA of TiO(2) in the visible light and increases stoichiometric decomposition of sulfur mustard against nondoped TiO(2) as well. PCA of TiO(2)/In(2)S(3) composite depends on the optimal ratio of TiO(2):In(2)S(3) in composite, while the activity for stoichiometric decomposition of sulfur mustards depends on the content of In(2)S(3) in nanocomposite.     

Strong Morphological Effect of Mn3O4 Nanocrystallites on the Catalytic Activity of Mn3O4 and Au/Mn3O4 in Benzene Combustion

Gold nanoparticles (3–4 nm) were deposited on Mn₃O₄ nanocrystallites with three distinct morphologies (cubic, hexagonal, and octahedral). The resulting structures were characterized, and their activities for benzene combustion were evaluated. The dominant exposed facets for the three kinds of Mn₃O₄ polyhedrons show the activity order: (103)≈(200)>(101). A similar activity order was derived for the interfaces between the Au and the Mn₃O₄ facet: Au/(200)≈Au/(103)>Au/(101). The metal–support interactions between the Au nanoclusters and specific facets of the Mn₃O₄ polyhedrons lead to a unique interfacial synergism in which the electronic modification of the Au nanoparticles and the morphology of the Mn₃O₄ substrate have a joint effect that is responsible for a significant enhancement in the catalytic activity of the Au/Mn₃O₄ system.     

Carbon coated nano-LiTi2(PO4)3 electrodes for non-aqueous hybrid supercapacitors

The Pechini type polymerizable complex decomposition method is employed to prepare LiTi(2)(PO(4))(3) at 1000 °C in air. High energy ball milling followed by carbon coating by the glucose-method yielded C-coated nano-LiTi(2)(PO(4))(3) (LTP) with a crystallite size of 80(±5) nm. The phase is characterized by X-ray diffraction, Rietveld refinement, thermogravimetry, SEM, HR-TEM and Raman spectra. Lithium cycling properties of LTP show that 1.75 moles of Li (~121 mA h g(-1) at 15 mA g(-1) current) per formula unit can be reversibly cycled between 2 and 3.4 V vs. Li with 83% capacity retention after 70 cycles. Cyclic voltammograms (CV) reveal the two-phase reaction mechanism during Li insertion/extraction. A hybrid electrochemical supercapacitor (HEC) with LTP as negative electrode and activated carbon (AC) as positive electrode in non-aqueous electrolyte is studied by CV at various scan rates and by galvanostatic cycling at various current rates up to 1000 cycles in the range 0-3 V. Results show that the HEC delivers a maximum energy density of 14 W h kg(-1) and a power density of 180 W kg(-1).     

Synthesis and characterization of ternary nanocomposites of TiO2/rGO/CdS as an efficient catalyst for photo-degradation of methyl orange

Novel ternary composite photocatalysts have been successfully prepared by TiO₂ nanofibers, reduced graphene oxide, and CdS nanoparticles (TiO₂/rGO/CdS) by using electrospinning technique with easy chemical methods. The structures and their properties are examined by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and field-emission scanning electron microscope (FESEM). The structural characterization of the composite reveals that pure TiO₂ NFs and CdS NPs crystalline very well and the reduced graphene oxide is tightly composed with TiO₂ NFs and CdS Nps. The photodegradation of methyl orange (MO) under UV light illumination is significantly enhanced compared with that of bare materials. This ternary composite degrades methyl orange within 75 min. The enhanced photocatalytic degradation performance resulted from effective separation of e–h pairs with rGO sheets and also contributed for high rate degradation efficiency. This novel ternary composite has a potential application of wastewater purification and utilization for energy conversions.     

Ag/Fe_3O_4/rGO纳米复合材料的制备及抗菌性能

以四水合氯化亚铁和硝酸银为原料,硼氢化钠为还原剂,氧化石墨烯(GO)为载体,通过原位还原法制备了具有磁分离功能的银/四氧化三铁/还原氧化石墨烯(Ag/Fe_3O_4/rGO)纳米复合抗菌材料.采用X射线粉末衍射仪(XRD)、X射线光电子能谱仪(XPS)、透射电子显微镜(TEM)等对复合材料进行了表征.结果显示,Fe_3O_4和Ag纳米颗粒均匀分布在rGO片层上.复合材料的饱和磁化率(Ms)为40.5 A·m~2·kg·(-1),表明其具有较强的磁性,将其与菌液混合后,在磁场作用下10 min即可吸附沉降完成磁分离.以大肠杆菌(E.coli)和金黄色葡萄球菌(S.aureus)为实验菌株,通过琼脂扩散法评价了复合材料的抗菌性能.结果表明,该复合材料具有良好的抗菌效果,对E.coli和S.aureus的抑菌圈直径分别为18 mm和13 mm,最低抑菌浓度值(MIC)分别为50 mg/L和80 mg/L,最低杀菌浓度值(MBC)分别为30 mg/L和50 mg/L.     

TiO2/SiO2/Fe3O4的制备及其光催化性能

TiO2/SiO2/Fe3O4的制备及其光催化性能;磁栽;光催化;脱色作用;Oraange     

One-step synthesis of an octahedral Mn3O4/rGO composite for use as an electrocatalyst in the oxygen reduction reaction

Journal of Solid State Electrochemistry - The development of low-cost, high-performance, non-precious-metal catalysts for the oxygen reduction reaction (ORR) is highly desirable. In this work, a...     

Facile preparation of MgAl2O4/CeO2/Mn3O4 heterojunction photocatalyst and enhanced photocatalytic activity

Novel Mn₃O₄-promoted double p?n junction MgAl₂O₄/CeO₂/Mn₃O₄ heterojunction photocatalyst was constructed by one-step synthesis method and two-step synthesis method. The X-ray powder diffraction, Fourier transform infrared spectrum, X-ray photoelectron spectroscopy, optical and photoluminescence demonstrated that the MgAl₂O₄/CeO₂/Mn₃O₄ heterojunction photocatalyst was synthesized by the two-step synthesis method comprehends a high crystallinity, charge carrier migration and separation efficiency, and relatively low optical absorption coefficient. The MgAl₂O₄/CeO₂/Mn₃O₄ heterojunction photocatalysts were efficiently used as simulated sunlight-driven n-n and p-n double junction photocatalyst for the simultaneous degradation of methylene blue (MB) dye. The continuous double p?n junction MgAl₂O₄/CeO₂/Mn₃O₄ heterojunctions strengthened the function of single n-n or p-n junction and guided the charge carrier migration and separation direction; thus, the oxidation and reduction reactions occur at the active site of spatial separation and prevent the recombination of electrons and holes. The results suggest that the continuous double p?n junction MgAl₂O₄/CeO₂/Mn₃O₄ heterojunctions are very promising candidate material for enhancing the photocatalytic activity in the photocatalytic degradation of MB dye.     

CoAl2O4包覆LiNi1/3Co1/3Mn1/3O2的电化学性能

通过共沉淀法制得类球形锂离子电池正极材料LiNi_1/3Co_1/3Mn_1/3O₂,并用非水相共沉法对其进行CoAl₂O₄包覆得到LNCMO(x). 采用X射线衍射（XRD）、扫描电子显微术（SEM）和透射电子显微术（TEM）测试材料的结构和观察材料形貌. 结果表明,CoAl₂O₄在材料表面形成8 nm均匀包覆层,未改变主体材料的结构. 电化学性能测试表明,1%（by mass）CoAl₂O₄包覆量的LiNi1/3Co1/3Mn1/3O2材料（LNCMO(1)）高充电电压（3.0 ~ 4.6 V,150 mA·g^-1）100周期循环放电容量保持率为93.7%（无包覆LNCMO(0)保持率为74.4%）;55 °C高温100周期循环容量保持率为77%（无包覆LNCMO(0)保持率17%）. XRD和电感耦合等离子体原子发射光谱（ICP-AES）测试表明,CoAl₂O₄包覆的LNCMO(x)材料可有效地减缓材料中Mn离子在电解液的溶解,提高材料结构稳定性和热稳定性.     

Mixed phase Fe2O3/Mn3O4 magnetic nanocomposite for enhanced adsorption of methyl orange dye: Neural network modeling and response surface methodology optimization

In this research, a novel magnetic mesoporous adsorbent with mixed phase of Fe₂O₃/Mn₃O₄ nanocomposite was prepared by a facile precipitating method and characterized extensively. The prepared nanocomposite was used as adsorbent for toxic methyl orange (MO) dye removal from aqua matrix considering its high surface area (178.27 m²/g) with high saturation magnetization (23.07 emu/g). Maximum dye adsorption occurs at solution pH 2.0 and the electrostatic attraction between anionic form of MO dye molecules and the positively charged nanocomposite surface is the main driving force behind this adsorption. Response surface methodology (RSM) was used for optimizing the process variables and maximum MO removal of 97.67% is obtained at optimum experimental condition with contact time, adsorbent dose and initial MO dye concentration of 45 min, 0.87 g/l and 116 mg/l, respectively. Artificial neural network (ANN) model with optimum topology of 3–5–1 was developed for predicting the MO removal (%), which has shown higher predictive ability than RSM model. Maximum adsorption capacity of this nanocomposite was found to be 322.58 mg/g from Langmuir isotherm model. Kinetic studies reveal the applicability of second‐order kinetic model with contribution of intra‐particle diffusion in this process.     

RuO2/Co3O4 thin films prepared by spray pyrolysis technique for supercapacitors

RuO₂/Co₃O₄ thin films with different RuO₂ content were successfully prepared on fluorine-doped tin oxide coated glass plate substrates by spray pyrolysis method, and their capacitive behavior was investigated. Electrochemical property was performed by cyclic voltammetry, constant current charge/discharge, and electrochemical impedance spectra. The capacitive performance of RuO₂/Co₃O₄ thin films with different RuO₂ content corresponded to a contribution from a main pseudocapacitance and an additional electric double-layer capacitance. The specific capacitance of pure Co₃O₄, 15.5%, 35.6%, and 62.3% RuO₂ composites at the current density of 0.2 A g⁻¹ were 394 ± 8, 453 ± 9, 520 ± 10, and 690 ± 14 F g⁻¹, respectively; 62.3% RuO₂ composite presented the highest specific capacitance value at various current densities, whereas 35.6% RuO₂ composite exhibited not only the largest specific capacitance contribution from RuO₂ (C _sp ^RuO2) at the current density of 0.5, 1.0, 1.5, and 2.0 A g⁻¹ but also the highest specific capacitance retention ratio (46.3 ± 2.8%) at the current density ranging from 0.2 to 2.0 A g⁻¹. Electrochemical impedance spectra showed that the contact resistance dropped gradually with the decrease of RuO₂ content, and the charge-transfer resistance (R _ct) increased gradually with the decrease of RuO₂ content.     

Surface phases and photocatalytic activity correlation of Bi2O3/Bi2O4-x nanocomposite

UV-visible irradiation induces surface alteration of Bi2O3 leading to Bi2O3/Bi2O4-x nanocomposites with excellent photocatalytic activity.