Facile synthesis of Cu-doped manganese oxide octahedral molecular sieve for the efficient degradation of sulfamethoxazole via peroxymonosulfate activation

Advanced processes for peroxymonosulfate(PMS)-based oxidation are efficient in eliminating toxic and refractory organic pol-lutants from sewage.The activation of electron-withdrawing HSO_(5)^(-)releases reactive species,including sulfate radical(·SO_(4)^(-)),hydroxyl radical(·OH),superoxide radical(·O_(2)^(-)),and singlet oxygen(1O_(2)),which can induce the degradation of organic contaminants.In this work,we synthesized a variety of M-OMS-2 nanorods(M=Co,Ni,Cu,Fe)by doping Co^(2+),Ni^(2+),Cu^(2+),or Fe^(3+)into manganese oxide oc-tahedral molecular sieve(OMS-2)to efficiently remove sulfamethoxazole(SMX)via PMS activation.The catalytic performance of M-OMS-2 in SMX elimination via PMS activation was assessed.The nanorods obtained in decreasing order of SMX removal rate were Cu-OMS-2(96.40%),Co-OMS-2(88.00%),Ni-OMS-2(87.20%),Fe-OMS-2(35.00%),and OMS-2(33.50%).Then,the kinetics and struc-ture-activity relationship of the M-OMS-2 nanorods during the elimination of SMX were investigated.The feasible mechanism underly-ing SMX degradation by the Cu-OMS-2/PMS system was further investigated with a quenching experiment,high-resolution mass spec-troscopy,and electron paramagnetic resonance.Results showed that SMX degradation efficiency was enhanced in seawater and tap water,demonstrating the potential application of Cu-OMS-2/PMS system in sewage treatment.

Triboelectric nanogenerator based on electrodeposited Ag octahedral nano-assemblies

The tremendous potential of triboelectric generators-TENGs for converting mechanical energy into electrical energy places them as one of the most promising energy harvesting technologies. In this work, the fabrication of enhanced performance TENGs using Ag octahedron nano-assemblies on ITO as electrodes significantly increases the electric charge collection of the induced tribocharges. Thereby, nanostructured electrical contacts coated with Ag macroscale nano-assemblies with octahedral features were obtained by the electrodeposition technique on flexible PET/ITO substrates. Consequently, the nanostructured triboelectric generator-TENG exhibited 65 times more maximum output power, and almost 10 times more open circuit output voltage than that of a TENG with non-nanostructured contacts passing from μW to m W capabilities, which was attributed to the increment of intrinsic interface states due to a higher effective contact area in the former. Likewise, output performances of TENGs also displayed an asymptotic behavior on the output voltage as the operating frequency of the mechanical oscillations increased, which is attributed to a decrement in the internal impedance of the device with frequency. Furthermore, it is shown that the resulting electrical output power can successfully drive low power consumption electronic devices. On that account, the present research establishes a promising platform which contributes in an original way to the development of the TENGs technology.

Octahedral Cu_2O-modified TiO_2 nanotube arrays for efficient photocatalytic reduction of CO_2

A photocatalyst composed of TiO 2 nanotube arrays（TNTs） and octahedral Cu2 O nanoparticles was fabricated,and its performance in the photocatalytic reduction of CO2 under visible and simulated solar irradiation was studied. The average nanotube diameter and length was 100 nm and 5 μm,respectively. The different amount of octahedral Cu2 O modified TNTs were obtained by varying electrochemical deposition time. TNTs modified with an optimized amount of Cu2 O nanoparticles exhibited high efficiency in the photocatalysis,and the predominant hydrocarbon product was methane. The methane yield increased with increasing Cu2 O content of the catalyst up to a certain deposition time,and decreased with further increase in Cu2 O deposition time. Insufficient deposition time（5 min） resulted in a small amount of Cu2 O nanoparticles on the TNTs,leading to the disadvantage of harvesting light. However,excess deposition time（45 min） gave rise to entire TNT surface being most covered with Cu2 O nanoparticles with large sizes,inconvenient for the transport of photo-generated carriers. The highest methane yield under simulated solar and visible light irradiation was observed for the catalysts prepared at a Cu2 O deposition time of 15 and 30 min respectively. The morphology,crystallization,photoresponse and electrochemical properties of the catalyst were characterized to understand the mechanism of its high photocatalytic activity. The TNT structure provided abundant active sites for the adsorption of reactants,and promoted the transport of photogenerated carriers that improved charge separation. Modifying the TNTs with octahedral Cu2 O nanoparticles promoted light absorption,and prevented the hydrocarbon product from oxidation. These factors provided the Cu2O-modified TNT photocatalyst with high efficiency in the reduction of CO2,without requiring co-catalysts or sacrificial agents.

Pt supported on octahedral Fe_3O_4 microcrystals as a catalyst for removal of formaldehyde under ambient conditions

Several catalysts comprising Pt supported on octahedral Fe3O4（Pt/Fe3O4） were prepared by a facile method involving co-precipitation followed by thermal treatment at different temperatures. A variety of characterization results revealed that this preparation process afforded highly crystalline octahedral Fe3O4 with a uniform distribution of Pt nanoparticles on its surface. The thermal-treatment temperature significantly influenced the redox properties of the Pt/Fe3O4 catalysts. All the Pt/Fe3O4 catalysts were found to be catalytically active and stable for the oxidation of low-concentration formaldehyde（HCHO） with oxygen. The catalyst prepared by thermal treatment at 80 °C（labelled Pt/Fe3O4-80） exhibited the highest catalytic activity, efficiently converting HCHO to CO2 and H2 O under ambient temperature and moisture conditions. The excellent performance of Pt/Fe3O4-80 was mainly attributed to beneficial interactions between the Pt and Fe species that result in the formation a higher density of active interface sites（e.g., Pt-O-FeO x and Pt-OH-FeO x）. The introduction of water vapor improves the catalytic activity of the Pt/Fe3O4 catalysts as it participates in a water-assisted dissociation process.

Evaluation of metal-doped manganese oxide octahedral molecular sieves in catalytic reduction of NO_x from cigarette mainstream smoke

A series of Ag,Cu and Co-doped manganese oxide octahedral molecular sieves(OMS-2) were synthesized and evaluated to remove nitrogen oxides(NOx) from cigarette mainstream smoke.The three kinds of catalysts were added to cigarettes for studying the capabilities of reducing NOx from cigarette mainstream smoke.The catalysis and reduction of NO in laboratory were studied.A mechanism for NOx catalytic reduction from burning cigarettes with the catalysts adding to cigarettes was described.The catalysts show excellent catalytic activity for NOx removal,especially the Ag-doped OMS-2 catalyst.0.5%(mass fraction) Ag-doped OMS-2 catalyst has the best ability to remove NOx from cigarette mainstream smoke.The use of Ag-doped OMS-2 as catalyst for removing carcinogenic compounds from cigarette smoke will be an effective strategy to protect the environment and public health.

One-pot Synthesis of Hollow Octahedral Cu_2O Nanostructures at Room Temperature

Homogeneous hollow Cu20 octahedral nanostructures have been fabricated by a facile onepot reduction reaction at roomtemperature. The microscope analysis revealed that the edges of as-prepared hollow structures were around 200 nm with a wall thickness of about 20 nm. To investigate the influence factors and formation mechanism of the hollow octahedral structure, samples subjected to different reaction conditions were studies. The results showed that the morphology and structures of Cu20 particles were greatly affected by the concentration of pH value of the reaction environment and the reaction time. Ostwald ripening process is orooosed to exolain the growth mechanism of the hollow octahedral nanostructures.

Magnetic properties of a mixed spin-3/2 and spin-2 Ising octahedral chain

Using an effective field theory with correlations, magnetic properties of an octahedral chain described by a mixed spin Ising model are investigated. Unique phenomena such as multiple hysteresis loops, saturation magnetization, and reverse flip of the magnetization plateaus occur when certain typical parameters are applied. These results may be helpful to further investigate the magnetic properties of one-dimensional systems and could potentially be utilized in the design of spin devices.

Magnetic and Electronic Properties of Double Perovskite Ba2SmNbO6 without Octahedral Tilting by First Principle Calculations

The structural, magnetic and electronic properties of the double perovskite Ba2SmNbO6 （for the simple cubic structure where no octahedral tilting exists anymore） are studied using the density functional theory within the generalized gradient approximation as well as taking into account the on-site Coulomb repulsive interaction. The total energy, the spin magnetic moment, the band structure and the density of states are calculated. The optimization of the lattice constants is 8.5173 A, which is in good agreement with the experimental value 8.5180 A. The calculations reveal that Ba2SmNbO6 has a stable ferromagnetic ground state and the spin magnetic moment per molecule is 5.00μB/f.u. which comes mostly from the Sin3＋ ion only. By analysis of the band structure, the compound exhibits the direct band gap material and half-metallic ferromagnetic nature with 100% spin-up polarization, which implies potential applications of this new lanthanide compound in magneto-electronic and spintronic devices.

Solvothermal Synthesis and Electrochemical Properties of Octahedral Cobalt Oxide Decorated with Ag_2O

Octahedral CoO with nanostructures decorated with Ag nanoparticles was prepared via a facile solvothermal approach. After being annealed at 500 ℃ for 1 h, an electrochemical capacitor material of Co3O4 decorated with Ag2O was obtained. The cyclic voltammetry and galvanostatic charge-discharge were used to evaluate the electrochemical properties of the as-prepared products. The results indicated that the as-prepared samples exhibited fine pseudo-capacitive performance, and the surface modifications of Ag2O can significantly increase the capacitance of the Co3O4 material. The specific capacitance of Ag2O/Co3O4 composite electrode was up to 217.6 F·g^-1, which was 3.35 times as high as that of pure Co3O4. Moreover, Ag2O/Co3O4 composite showed an excellent cycle performance, and 65.3% of specific capacitance was maintained after 200 cycles.

Improved photocatalytic performance of acetaldehyde degradation via crystal plane regulation on truncated octahedral CeO_(2)

In this study,the truncated octahedral CeO_(2)(CeO_(2)-to)with special morphology was prepared by the solvothermal method with oleic acid(OA)and oleamine(OM)as the morphology-directing agents.High-resolution transmission electron microscopy(HRTEM)results show that CeO_(2)-to exposes composite{100}and{111}facets,while CeO_(2)cubic(CeO_(2)-c)and CeO_(2)octahedral(CeO_(2)-o)only expose single crystal facets of{100}plane and{111}plane,respectively.Interestingly,this CeO_(2)-to photocatalyst exhibits remarkable photooxidation performance of gaseous acetaldehyde(CH_(3)CHO)degradation,in which CO_(2)generation value reaches 1.78 and 7.97-times greater than that of CeO_(2)-c and CeO_(2)-o,respectively.In addition,the active species trapping experiment signifies that superoxide(·O_(2)^(-))and holes(h^(+))are the main reactive substances during the CH_(3)CHO degradation process,and the electron paramagnetic resonance(EPR)spectra indicates that the former is the major contributor.Notably,the electron transfer mechanism between CeO_(2)-to{100}and{111}facets and the surface oxygen adsorption ability are revealed via density functional theory(DFT)calculations.It is also confirmed that{100}facets are more conducive to the absorption of acetaldehyde than{111}facets.Finally,a reasonable mechanism for improved photocatalytic CH_(3)CHO degradation on CeO_(2)-to is proposed based on relevant experiments and DFT calculations.This study demonstrates that the systematic development of surface homojunction structured photocatalysts can efficiently increase the degradation activity for volatile organic compounds(VOCs).It also offers additional direction for optimizing the photocatalytic activity of other ceriumbased photocatalysts.

Enhanced macrophage polarization induced by COX-2 inhibitor-loaded Pd octahedral nanozymes for treatment of atherosclerosis

Inhibition of foam cell formation is considered a promising treatment method for atherosclerosis,the leading cause of cardiovascular diseases worldwide.However,currently available therapeutic strategies have shown unsatisfactory clinical outcomes.Thus,herein,we design aloperine(ALO)-loaded and hyaluronic acid(HA)-modified palladium(Pd)octahedral nanozymes(Pd@HA/ALO)that can synergistically scavenge reactive oxygen species(ROS)and downregulate cyclooxygenase-2(COX-2)expression to induce macrophage polarization,thus inhibiting foam cell formation to attenuate atherosclerosis.Due to the targeted effect of HA on stabilin-2 and CD44,which are overexpressed in atherosclerotic plaques,Pd@HA/ALO can actively accumulate in atherosclerotic plaques.Subsequently,the antioxidative effects of Pd octahedral nanozymes are mediated by their intrinsic superoxide dismutase-and catalase-like activities capable of effective scavenging of ROS.In addition,anti-inflammatory effects are mediated by controlled,on-demand near-infrared-triggered ALO release leading to inhibition of COX-2 expression.Importantly,the combined therapy can promote the polarization of macrophages to the M2 subtype by upregulating Arg-1 and CD206 expression and downregulating expression of TNF-α,IL-1βand IL-6,thereby inhibiting atherosclerosis-related foam cell formation.In conclusion,the presented in vitro and in vivo data demonstrate that Pd@HA/ALO enhanced macrophage polarization to reduce plaque formation,identifying an attractive treatment strategy for cardiovascular disease.

Magnetic Interactions with Strain Gradient in Ultrathin Pr_(0.67)Sr_(0.33)MnO_(3) Films

Strain gradient is a normal phenomenon around a heterostructural interface in ultrathin film,and it is important to determine its effect on magnetic interactions to understand interfacial coupling.In this work,ultrathin Pr_(0.67)Sr_(0.33)MnO_(3)(PSMO)films on different substrates are studied.For PSMO film under different in-plane strain conditions,the saturated magnetization and Curie temperature can be qualitatively explained by double-exchange interaction and the Jahn-Teller distortion.However,the difference in the saturated magnetization with zero field cooling and 5 T field cooling is proportional to the strain gradient.Strain-gradient-induced structural disorder is proposed to enhance phonon-electron antiferromagnetic interactions and the corresponding antiferromagnetic-to-ferromagnetic phase transition via a strong magnetic field during the field cooling process.A non-monotonous structural transition of the MnO_(6) octahedral rotation can enlarge the strain gradient in PSMO film on a SrTiO_(3) substrate.This work demonstrates the existence of the flexomagnetic effect in ultrathin manganite film,which should be applicable to other complex oxide systems.

Some Salicylato New Organotin (IV) and Copper Chloride Adducts and Derivative: Synthesis and Spectroscopic Study

Three new salicylate complexes and derivatives have been synthesized and studied by infrared, 119Sn NMR and UV-visible spectroscopies. The suggested structures for the two compounds are discrete with NH-O and NH-Cl hydrogen bonds. The salicylate oxyanion is monochelating for the first salicylate compound with an octahedral tin (IV) centre and monodentate for the second salicylate compound, the environments around the tin centre being tetrahedral. For the cooper complex, the salicylate ligand is monochelating and the environments around the copper atom centre are tetrahedral.

Antiferromagnetic element Mn modified PtCo truncated octahedral nanoparticles with enhanced activity and durability for direct methanol fuel cells

Pt-based magnetic nano catalysts are one of the most suitable cand idates for electrocatalytic materials due to their high electrochemistry activity and retrievability.Unfortunately,the inferior durability prevents them from being scaled-up,limiting their commercial applications.Herein,an antiferromagnetic element Mn was introduced into PtCo nanostructured alloy to synthesize uniform Mn-PtCo truncated octahedral nanoparticles(TONPs)by one-pot method.Our results show that Mn can tune the blocking temperature of Mn-PtCo TONPs due to its an tiferromag netism.At low temperatures,Mn-PtCo TONPs are ferromag netic,and the coercivity in creases gradually with in creasi ng Mn contents.At room temperature,the Mn-PtCo TONPs display superparamag netic behavior,which is greatly helpful for in dustrial recycling.Mn doping can not only modify the electronic structure of PtCo TONPs but also enhanee electrocatalytic performance for methanol oxidation reaction.The maximum specific activity of Mn-PtCo-3 reaches 8.1 A`m^-2,3.6 times of commercial Pt/C(2.2 A·m^-2)and 1.4 times of PtCo TONPs(5.6 A`m^-2),respectively.The mass activity decreases by only 30%after 2,000 cycles,while it is 45%and 99%(nearly inactive)for PtCo TONPs and commercial Pt/C catalysts,respectively.

Shape-Controlled Synthesis of Octahedral α-NaYF_(4) and Its Rare Earth Doped Submicrometer Particles in Acetic Acid

Submicrometer sized pure cubic phase,Eu^(3+)doped,and Yb^(3+)/Er^(3+)co-dopedα-NaYF4 particles with octahedral morphology have been prepared in acetic acid.The acetate anion plays a critical role in the formation of such symmetric octahedral structures through its selective adsorption on the(111)faces of the products.The size of the as-prepared octahedra can be tuned by varying the amount of sodium acetate added to the acetic acid.A possible formation mechanism for these octahedra has been proposed.The dopedα-NaYF_(4) octahedral submicrometer particles show down-conversion and up-conversion photoluminescence typical of these materials.

Surface composition-tunable octahedral PtCu nanoalloys advance the electrocatalytic performance on methanol and ethanol oxidation

The synthesis of surface composition-tunable Pt-based octahedral nanoalloys is key to unravel the structureproperty relationship in fuel cells. Herein, we report a facile route to prepare composition-tunable Pt Cu octahedral nanoalloys by using halogen ions(Br-or/and I-) as composition modulators. Among these Pt Cu octahedral nanoalloys,Pt59 Cu41 octahedron exhibits the highest catalytic activity and durability in alkaline solution. The specific activity/mass activity of Pt59 Cu41 octahedron is 20.25 m A cm^-2/3.24 A mg^-1 Pt,which is 6.64/5.3 times higher than commercial Pt black in 0.5 mol L^-1 CH3 OH, respectively. In the case of using ethanol(0.5 mol L^-1) as fuel source, Pt59 Cu41 octahedron shows much better catalytic activity, that is 34.84 m A cm^-2/5.58 A mg^-1 Pt for specific activity/mass activity, which is 9.16/7.34 times higher than commercial Pt black, respectively. In situ Fourier transform infrared spectroscopy is employed to detect the intermediate species and products for methanol/ethanol oxidation reaction and a plausible mechanism is proposed to explain the improved activity and durability of Pt59 Cu41 octahedron toward methanol/ethanol oxidation in alkaline medium.

Material exploration via designing spatial arrangement of octahedral units: a case study of lead halide perovskites

Halide perovskites have attracted tremendous attention as semiconducting materials for various optoelectronic applications.The functional metal-halide octahedral units and their spatial arrangements play a key role in the optoelectronic properties of these materials.At present,most of the efforts for material exploration focus on substituting the constituent elements of functional octahedral units,whereas designing the spatial arrangement of the functional units has received relatively little consideration.In this work,via a global structure search based on density functional theory(DFT),we discovered a metastable three-dimensional honeycomb-like perovskite structure with the functional octahedral units arranged through mixed edge-and comer-sharing.We experimentally confirmed that the honeycomb-like perovskite structure can be stabilized by divalent molecular cations with suitable size and shape,such as 2,2’-bisimidazole(BIM).DFT calculations and experimental characterizations revealed that the honeycomb-like perovskite with the formula of BIMPb2l6,synthesized through a solution process,exhibits high electronic dimensionality,a direct allowed bandgap of 2.1 eV,small effective masses for both electrons and holes,and high optical absorption coefficients,which indicates a significant potential for optoelectronic applications.The employed combination of DFT and experimental study provides an exemplary approach to explore prospective optoelectronic semiconductors via spatially arranging functional units.

Controlled synthesis and magnetic properties of Fe_3O_4 walnut spherical particles and octahedral microcrystals

Magnetite Fe3O4 walnut spherical particles and octahedral microcrystals were suc- cessfully synthesized from K4 [Fe (CN) 6], K3 [Fe (CN) 6] and NaOH reagents via a simple hydrothermal process. And the uniform morphology of octahedral micro- crystals was obtained in the presence of ethylene glycol. The morphology and structure of products were characterized by powder X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results showed that the Fe3O4 walnut spherical particles and octahedral microcrystals were single crystals with the face-center cubic structure and with size distributions from 2.2 to 8.6 μm and 1.6 to 12.5 μm, respectively. Their magnetic properties were detected by a vibrating sample magnetometer at room temperature. The walnut spherical parti- cles exhibited a ferromagnetic behavior with the coercive force (Hc), saturation magnetization (Ms) and remanent magnetization (Mr) being 150.57 Oe, 97.634 and 12.05 emu/g, respectively. For the octahedral microcrystals they were 75.28 Oe, 101.90 and 6.69 emu/g, respectively. Different sizes of walnut spherical particles were controlled synthesized through adjusting the NaOH concentration. It was found that ethylene glycol molecules have a significant effect on the formation of Fe3O4 octahedra. A possible mechanism was also proposed to account for the growth of these Fe3O4 products

Octahedral PtNi nanoparticles with controlled surface structure and composition for oxygen reduction reaction

Controlling the surface structure and composi- tion at the atomic level is an effective way to tune the cat- alytic properties of bimetallic catalysts. Herein, we demon- strate a generalized strategy to synthesize highly monodis- perse, surfactant-free octahedral PtxNi1-x nanoparticles with tunable surface structure and composition. With increasing the Ni content in the bulk composition, the degree of concave- ness of the octahedral PtxNi1-x nanoparticles increases. We systematically studied the correlation between their surface structure/composition and their observed oxygen reduction activity. Electrochemical studies have shown that all the octa- hedral PtxNi1-x nanoparticles exhibit enhanced oxygen reduc- tion activity relative to the state-of-the-art commercial Pt/C catalyst. More importantly, we find that the surface struc- ture and composition of the octahedral PtxNi1-x nanoparti- cles have significant effect on their oxygen reduction activ- ity. Among the studied PtxNi1-x nanoparticles, the octahedral PtlNi1 nauoparticles with slight concaveness in its （111） facet show the highest activity. At 0.90 V vs. RHE, the Pt mass and specific activity of the octahedral PhNil nanoparticles are 7.0 and 7.5-fold higher than that of commercial Pt/C catalyst, re- spectively. The present work not only provides a generalized strategy to synthesize highly monodisperse, surfactant-free octahedral PtxNi1-x nanoparticles with tunable surface struc- ture and composition, but also provides insights to the struc- ture-activity correlation.

High performance octahedral PtNi/C catalysts investigated from rotating disk electrode to membrane electrode assembly

Octahedral PtNi/C catalysts have demonstrated superior catalytic performance in oxyge n reduction reacti on (ORR) over commercial Pt/C with rotating disk electrode (RDE). However, it is not trivial to translate such promising results to real-world membrane-electrode assembly (MEA). In this work, we have synthesized octahedral PtNi/C catalysts using poly(diallyldimethylammonium chloride)(PDDA) as a capping age nt and in vestigated their performance from RDE to MEA. In RDE, mass activity and specific activity of the optimized octahedral PtNi/C catalyst for oxygen reduction reaction (ORR) are nearly 19 and 28 times high of the state-of-the-art commercial Pt/C, respectively. At MEA level, the octahedral PtNi/C catalyst exhibits excelle nt power generation performa nee and durability paired with commercial Pt/C ano de. Its cell voltage at 1,000mA·cm^-2 reaches 0.712 V, and maximum power density is 881.6 mW·cm^-2 and its performance attenuation is also less, around 11.8% and 7% under galvanostatic condition of 1,000 mA·cm^-2 for 100 h. Such results are investiaged by thermodynamic analysis and fundametal performance modeling, which indicate the single cell performance can be further improved by reducing the size of PtNi/C catalyst agglomerates. Such encouraging results have demonstrated the feasibility to convey the superior performance of octahedral PtNi/C from RDE to MEA.