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All-solid-state Z-scheme photocatalysts for overall water splitting to evolve H2 is a promising strategy for efficient conversion of solar energy. However, most of these strategies require redox mediators. Herein, a direct Z-scheme photoelectrocatalytic electrode based on a WO3-x nanowire-bridged TiO2 nanorod array heterojunction is constructed for overall water splitting, producing H2. The as-prepared WO3-x/TiO2 nanorod array heterojunction shows photoelectrochemical (PEC) overall water splitting activity evolving both H2 and O2 under UV–vis light irradiation. An optimum PEC activity was achieved over a 1.67-WO3-x/TiO2 photoelectrode yielding maximum H2 and O2 evolution rates roughly 11 times higher than that of pure TiO2 nanorods without any sacrificial agent or redox mediator. The role of oxygen vacancy in WO3-x in affecting the H2 production rate was also comprehensively studied. The superior PEC activity of the WO3-x/TiO2 electrode for overall water splitting can be ascribed to an efficient Z-scheme charge transfer pathway between the WO3-x nanowires and TiO2 nanorods, the presence of oxygen vacancies in WO3-x, and a bias potential applied on the photoelectrode, resulting in effective spatial charge separation. This study provides a novel strategy for developing highly efficient PECs for overall water splitting.

Low-cost transition-metal oxide is regarded as a promising electrocatalyst family for an oxygen evolution reaction (OER). The classic design principle for an oxide electrocatalyst believes that point defect engineering, such as oxygen vacancies (VO..) or heteroatom doping, offers the opportunities to manipulate the electronic structure of material toward optimal OER activity. Oppositely, in this work, we discover a counterintuitive phenomenon that both VO.. and an aliovalent dopant (i.e., proton (H+)) in perovskite nickelate (i.e., NdNiO3 (NNO)) have a considerably detrimental effect on intrinsic OER performance. Detailed characterizations unveil that the introduction of these point defects leads to a decrease in the oxidative state of Ni and weakens Ni-O orbital hybridization, which triggers the local electron-electron correlation and a more insulating state. Evidenced by first-principles calculation using the density functional theory (DFT) method, the OER on nickelate electrocatalysts follows the lattice oxygen mechanism (LOM). The incorporation of point defect increases the energy barrier of transformation from OO*(VO) to OH*(VO) intermediates, which is regarded as the rate-determining step (RDS). This work offers a new and significant perspective of the role that lattice defects play in the OER process.

The regulation of reactive centers by involving the participation of lattice oxygen has been reported as an effective strategy for lowering the reaction barrier for the oxygen evolution reaction (O...

Double perovskite oxides are one of the most promising bifunctional electrocatalysts for efficient oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) due to their adjustable electronic structures via doping with different metal cations or engineering of defects. Herein, we report a systematic study on the tuning of the electronic structure of La2-xSrxNiMnO6 with 0 ≤ x ≤ 1.0 to promote the bifunctional OER/ORR activity. The bifunctional index (ΔE) is substantially reduced with increasing of Sr contents and achieves an optimal value of 0.85 V for La1.4Sr0.6NiMnO6, exceeding that of widely studied LaNiO3. Our study on electronic structures reveals that the enhancement of the ORR and OER activities strongly correlates with the appearance of Ni3+ oxidation states and the upshift of the O 2p-band center promoted by Sr doping. Furthermore, an increase of hole states, derived from Ni3+ states, reduces the energy barrier for the electron transfer from 0.44 to 0.12 eV and hence improves the intrinsic OER activities. The tuning of the electronic structure that leads to higher OER and ORR activities in La2-xSrxNiMnO6 can be extended to other materials for the design of active bifunctional electrocatalysts.

Lithium cobalt oxide (LCO) is the dominating cathode materials for lithium-ion batteries (LIBs) deployed in consumer electronic devices for its superior volumetric energy density and electrochemical performances. The constantly increasing demands of higher energy density urge to develop high-voltage LCO via a variety of strategies. However, the corresponding modification mechanism, especially the influence of the long- and short-range structural transitions at high-voltage on electrochemical performance, is still not well understood and needs further exploration. Based on ss-NMR, in-situ X-ray diffraction, and electrochemical performance results, it is revealed that the H3 to H1-3 phase transition dictates the structural reversibility and stability of LCO, thereby determining the electrochemical performance. The introduction of La and Al ions could postpone the appearance of H1-3 phase and induce various types of local environments to alleviate the volume variation at the atomic level, leading to better reversibility of the H1-3 phase and smaller lattice strain, and significantly improved cycle performance. Such a comprehensive long-range, local, and electronic structure characterization enables an in-depth understanding of the structural evolution of LCO, providing a guiding principle for developing high-voltage LCO for high energy density LIBs.

In this paper, we report insights into the local atomic and electronic structure of ${\mathrm{NiCo}}_{2}{\mathrm{O}}_{4}$ epitaxial thin films and its correlation with electrical, optical, and magnetic properties. We grew structurally well-defined ${\mathrm{NiCo}}_{2}{\mathrm{O}}_{4}$ epitaxial thin films with controlled properties on $\mathrm{Mg}{\mathrm{Al}}_{2}{\mathrm{O}}_{4}(001)$ substrates using pulsed laser deposition. Films grown at low temperatures ($l400{\phantom{\rule{0.28em}{0ex}}}^{\ensuremath{\circ}}\mathrm{C}$) exhibit a ferrimagnetic and metallic behavior, while those grown at high temperatures are nonmagnetic semiconductors. The electronic structure and cation local atomic coordination of the respective films were investigated using a combination of resonant photoemission spectroscopy, x-ray absorption spectroscopy, and ab initio calculations. Our results unambiguously reveal that the ${\mathrm{Ni}}^{3+}$ valence state promoted at low growth temperature introduces delocalized $\mathrm{Ni}\phantom{\rule{0.28em}{0ex}}3d$-derived states at the Fermi level (${E}_{F}$), responsible for the metallic state in ${\mathrm{NiCo}}_{2}{\mathrm{O}}_{4}$, while the $\mathrm{Co}\phantom{\rule{0.28em}{0ex}}3d$-related state is more localized at higher binding energy. In the semiconducting films, the valence state of Ni is lowered and $\ensuremath{\sim}+2$. Further structural and defect chemistry studies indicate that the formation of oxygen vacancies and secondary CoO phases at high growth temperature are responsible for the ${\mathrm{Ni}}^{2+}$ valence state in ${\mathrm{NiCo}}_{2}{\mathrm{O}}_{4}$. The $\mathrm{Ni}\phantom{\rule{0.28em}{0ex}}3d$-related state becomes localized away from ${E}_{F}$, opening a band gap for a semiconducting state. The band gap of the semiconducting ${\mathrm{NiCo}}_{2}{\mathrm{O}}_{4}$ is estimated to be $l0.8\phantom{\rule{0.28em}{0ex}}\mathrm{eV}$, which is much smaller than the quoted values in the literature ranging from 1.1 to 2.58 eV. Despite the small band gap, its optical transition is $d\text{\ensuremath{-}}d$ dipole forbidden, and therefore, the semiconducting ${\mathrm{NiCo}}_{2}{\mathrm{O}}_{4}$ still shows reasonable transparency in the infrared-visible light region. The present insights into the role of ${\mathrm{Ni}}^{3+}$ in determining the electronic structure and defect chemistry of ${\mathrm{NiCo}}_{2}{\mathrm{O}}_{4}$ provide important guidance for use of ${\mathrm{NiCo}}_{2}{\mathrm{O}}_{4}$ in electrocatalysis and opto-electronics.

Cobalt oxides with multiple local Co-O coordination environments such as octahedral, tetrahedral, and tetragonal networks display versatile electronic and magnetic properties which have attracted great interest in many fields. Understanding the ground-state properties and determining the fundamental band gap remain challenges in cobalt-based compounds and thin films, which have been investigated here using synchrotron-based Co ${L}_{23}$-edge x-ray absorption measurements followed by configuration interaction cluster calculations. We focus on the detailed Co ${L}_{23}$-edge absorption spectral variations in different octahedral crystal fields as well as in the less investigated tetrahedral and tetragonal systems, taking into account Co ions with different valence states. From a quantitative comparison between the simulated spectrum and an accurately measured absorption spectrum of a specified compound, the crystal field value can be extracted from the Co ${L}_{23}$-edge absorption spectrum, which is complementary to the results obtained in optical measurements and other calculations. Furthermore, Co ${L}_{23}$-edge x-ray linear dichroism shows the same spectral evolutions as a result of either local ${\mathrm{CoO}}_{6}$ cluster with tetragonal symmetry or the magnetic exchange field, whereas both coexist in most antiferromagnetic cobalt oxide thin films. Detailed temperature and polarization-dependent Co ${L}_{23}$-edge absorption measurements have been proposed to distinguish both contributions, which show different spectral variations due to the specified modifications of the ground and final states at different temperatures. Our results offer theoretical guidance for understanding the multiplet structure of Co ${L}_{23}$-edge absorption spectrum, obtaining the precise crystal field value for cobalt oxides with versatile coordinations, and explaining the underlying mechanism of x-ray linear dichroism, as well as understanding the fundamental physical properties and their potential applicability of cobalt oxides and their thin films.

The beneficial effect of surface photoreduction on the photoresponse of copper bismuthate is reported for the first time. A detailed photoemission spectroscopy study (PES) reveals that irradiation of CuBi2O4 with hν ≥ 2.7 eV in an inert atmosphere leads to the formation of reduced surface Cu. Surface states associated with reduced Cu species induce a 0.35 eV downward band bending, which improves the charge carrier transport properties of this material as judged by a measured increase of the characteristic surface photovoltage (SPV) from 0.07 to 0.27 V. In connection with this PES study, improvements of up to 30% in the photoresponse are observed for CuBi2O4 photocathodes that have been subjected to a visible light irradiation (100 mW/cm2 white LED) in argon prior to photoelectrochemical performance testing using H2O2 as an electron scavenger. The stability of reduced surface states and associated SPV under relevant reaction conditions has been further studied by near-ambient pressure PES. Results indicate that reduced surface states remain stable in the presence of Ar and methanol, but reoxidation of surface Cu occurs in the presence of oxygen, which decreases the measured SPV. Hence, this work establishes a direct relationship between the presence of reduced Cu at the surface and SPV of CuBi2O4, having important implications on its photovoltaic properties. A similar downward band bending is observed at the interface between CuBi2O4 and a Cu thin film deposited by physical vapor deposition, which further highlights the importance of the Cu/CuBi2O4 buried interface in photoelectrodes.

AIM To discuss the effects and mechanism of microRNA-34a in cell apoptosis induced by osteoarthritis. METHODS Collection of the normal and osteoarthritis synovial tissues and measurements of the miRNA-34a and TGIF2 gene expression. In the cell experiment, the cells were divided into Control, Blank and miRNA inhibitor group. The cell proliferation and apoptosis of the different groups were measured by MTT and flow cytometry and the TGIF2 protein expression in the different groups was evaluated by WB assay. The correlation between TGIF2 and miRNA-34a was analyzed by Double luciferase experiment. RESULTS Compared with normal synovial tissues, the miRNA-34a gene expression was significantly up-regulated and TGIF2 gene expression was significantly suppressed in osteoarthritis synovial tissues (p < 0.001, respectively). The cell proliferation was significantly depressed and the cell apoptosis rate was significantly increased in miRNA inhibitor group compared with the Control group (p < 0.001, respectively). Using the WB assay it was shown that the TGIF2 protein expression of miRNA inhibitor group was significantly suppressed compared with that of Control group (p < 0.01). By Double luciferase assay, TGIF2 gene was one target gene of miRNA-34a. CONCLUSION miRNA-34a could induce osteoarthritis synovial cell apoptosis via regulation of TGIF2 in vitro (Fig. 6, Ref. 29).

Interfacial charge transfer from silicon to heterogeneous catalysts plays a key role in silicon-based photoelectrochemical systems. In general, prior to interfacial charge transfer, carriers that are generated by photons with energies above the bandgap dissipate the excess kinetic energy via hot-carrier cooling, and such energy loss limits the maximum power conversion efficiency. The excess energy of hot-carriers, however, could be utilized through hot-carrier transfer from silicon to the catalysts, but such hot-carrier extraction has not yet been demonstrated. Here, we exploit transient reflection spectroscopy to interrogate charge transfer at the interface between silicon and platinum. Quantitative modeling of the surface carrier kinetics indicates that the velocity of charge transfer from silicon to platinum exceeds 2.6 × 107 cm s-1, corresponding to an average carrier temperature of extracted carriers of ∼600 K, two times higher than the lattice temperature. The charge transfer velocity can be controllably reduced by inserting silica spacing layers between silicon and platinum.

Organic-inorganic perovskite solar cells have attracted significant attention due to their remarkable performance. The use of alternative metal-oxide charge-transport layers is a strategy to improving device reliability for large-scale fabrication and long-term applications. Here, we report solution-processed perovskite solar cells employing nickel oxide hole-extraction layers produced in situ using an atmospheric pressure spatial atomic-layer deposition system, which is compatible with high-throughput processing of electronic devices from solution. Our sub-nanometer smooth (average roughness of ≤0.6 nm) oxide films enable the efficient collection of holes and the formation of perovskite absorbers with high electronic quality. Initial solar-cell experiments show a power-conversion efficiency of 17.1%, near-unity ideality factors, and a fill factor of >80% with negligible hysteresis. Transient measurements reveal that a key contributor to this performance is the reduced luminescence quenching trap density in the perovskite/nickel oxide structure.

In this work, we report the synthesis of a Bi2O3-TiO2 hetero-junction (HJ) material through a facile colloidal method. The hetero-junction formation follows a growth with a 145°Bi2O3/TiO2 crystal angle, owing to the large lattice mismatch between Bi2O3 and TiO2 crystals. With the Bi2O3-TiO2 hetero-junction material as a photocatalyst, methyl orange is degraded completely within two hours under common UV-lamp irradiation. The photo-catalyst remains highly-active for complete photo-degradation of methyl orange even after multiple experiments. The remarkable photo-catalytic properties are attributed to the remarkable mono-dispersivity of the colloidal Bi2O3-TiO2 nano-structure as well as the refined band structure with a valence band of 0.85 eV below that of TiO2 crystal.

Changes in the structure and composition resulting from oxygen deficiency can strongly impact the physical and chemical properties of transition-metal oxides, which may lead to new functionalities for novel electronic devices. Oxygen vacancies (VO) can be readily formed to accommodate the lattice mismatch during epitaxial thin film growth. In this paper, the effects of substrate strain and oxidizing power on the creation and distribution of VO in WO3-δ thin films are investigated in detail. An 18O2 isotope-labeled time-of-flight secondary-ion mass spectrometry study reveals that WO3-δ films grown on SrTiO3 substrates display a significantly larger oxygen vacancy gradient along the growth direction compared to those grown on LaAlO3 substrates. This result is corroborated by scanning transmission electron microscopy imaging, which reveals a large number of defects close to the interface to accommodate interfacial tensile strain, leading to the ordering of VO and the formation of semi-aligned Magneli phases. The strain is gradually released and a tetragonal phase with much better crystallinity is observed at the film/vacuum interface. The changes in the structure resulting from oxygen defect creation are shown to have a direct impact on the electronic and optical properties of the films.

Catalytic conversion of CO2 into chemicals is a critical issue for energy and environmental research. Among such reactions, converting CO2 into CO has been regarded as a significant foundation to generate a liquid fuels and chemicals on a large scale. In this work, zeolitic imidazolate framework-derived N-doped carbon-supported metal carbide catalysts (M/ZIF-8-C; M=Ni, Fe, Co and Cu) with highly dispersed metal carbide were prepared for selective CO2 hydrogenation. Under the same metal loadings, catalytic activity for CO2 hydrogenation to CO follows the order: Ni/ZIF-8-C≈Fe/ZIF-8-C>Co/ZIF-8-C>Cu/ZIF-8-C. These catalysts are composed of carbide or metal supported on pyridinic N sites within the N-doped carbon structure. ZIF-8-derived pyridinic nitrogen and carbide effect CO2 adsorption, whereas dispersed Ni or Fe carbide and metal species serve as an active site for CO2 hydrogenation. The supported Ni catalyst exhibits extraordinary catalytic performance, which results from high dispersion of the metal and exposure of the carbide. Based on high-sensitivity low-energy ion scattering (HS-LEIS) and line scan results, density functional theory (DFT) was used to understand reaction mechanism of selective CO2 hydrogenation over Ni/ZIF-8-C. The product CO is derived mainly from the direct cleavage of C-O bonds in CO2 * rather than decomposition of COOH*. The CO* desorption energy on Ni/ZIF-8-C is lower than that for further hydrogenation and dissociation. Comparison of Ni/ZIF-8-C with ZIF-8-C indicates that the combined effects of the highly dispersed metal or carbide and weak CO adsorption result in high CO selectivity for CO2 hydrogenation.

Bismuth ferrite BiFeO3 (BFO) is an important ferroelectric material for thin-film optoelectronic sensing and potential photovoltaic applications. Its relatively large band gap, however, limits the conversion efficiency of BFO absorber-based PV devices. In this study, based on density functional theory calculations we demonstrate that with well-designed Fe-site elemental substitution, tetragonal BFO can exhibit a much lower fundamental band gap than that of conventional rhombohedral BFO without forming in-gap electronic states and unravelling the underlying mechanisms. Cation atomic size, electronegativity, and crystallographic symmetry are evidenced as critical parameters to tailor the metal 3d–oxygen 2p orbital interactions and thus intrinsically modify the electronic structure, particularly, the shape and character of the valence and conduction band edges. With the reduced band gap, improved mobility, and uncompromised ferroelectric and magnetic ground states, the present results provide a new strategy of designing high symmetry BFO for efficient optoelectronic applications.

Transition metal chalcogenides represent a class of the most promising alternative electrode materials for high-performance lithium-ion batteries (LIBs) owing to their high theoretical capacities. However, they suffer from large volume expansion, particle agglomeration, and low conductivity during charge/discharge processes, leading to unsatisfactory energy storage performance. In order to address these issues, we rationally designed three-dimensional (3D) hybrid composites consisting of ZnSe nanodots uniformly confined within a N-doped porous carbon network (ZnSe ND@N-PC) obtained via a convenient pyrolysis process. When used as anodes for LIBs, the composites exhibited outstanding electrochemical performance, with a high reversible capacity (1,134 mA·h·g−1 at a current density of 600 mA·g−1 after 500 cycles) and excellent rate capability (696 and 474 mA·h·g−1 at current densities of 6.4 and 12.8 A·g−1, respectively). The significantly improved lithium storage performance can be attributed to the 3D architecture of the hybrid composites, which not only mitigated the internal mechanical stress induced by the volume change and formed a 3D conductive network during cycling, but also provided a large reactive area and reduced the lithium diffusion distance. The strategy reported here may open a new avenue for the design of other multifunctional composites towards high-performance energy storage devices.

This work reports a fundamental study on the electronic structure, optical properties, and defect chemistry of a series of Co-based spinel oxide ( Co 3 O 4 , ZnCo 2 O 4 , and CoAl 2 O 4 ) epitaxial thin films using x-ray photoemission and absorption spectroscopies, optical spectroscopy, transport measurements, and density functional theory. We demonstrate that ZnCo 2 O 4 has a fundamental bandgap of 1.3 eV, much smaller than the generally accepted values, which range from 2.26 to 2.8 eV. The valence band edge mainly consists of occupied Co 3 d t 2 g 6 with some hybridization with O 2 p /Zn 3 d , and the conduction band edge of unoccupied e g * state. However, optical transition between the two band edges is dipole forbidden. Strong absorption occurs at photon energies above 2.6 eV, explaining the reasonable transparency of ZnCo 2 O 4 . A detailed defect chemistry study indicates that Zn vacancies formed at high oxygen pressure are the origin of a high p -type conductivity of ZnCo 2 O 4 , and the hole conduction mechanism is described by small-polaron hoping model. The high p -type conductivity, reasonable transparency, and large work function make ZnCo 2 O 4 a desirable p -type transparent semiconductor for various optoelectronic applications. Using the same method, the bandgap of Co 3 O 4 is further proved to be ∼0.8 eV arising from the tetrahedrally coordinated Co 2 + cations. Our work advances the fundamental understanding of these materials and provides significant guidance for their use in catalysis, electronic, and solar applications.

Hydrogenation of transition metal oxides offers a powerful platform to tailor physical functionalities as well as for potential applications in modern electronic technologies. An ideal nondestructive and efficient hydrogen incorporation approach is important for the realistic technological applications. We demonstrate the proton injection on SrCrO3 thin films via an efficient low-energy hydrogen plasma implantation experiments, without destroying the original lattice framework. Hydrogen ions accumulate largely at the interfacial regions with amorphous character which extend about one-third of the total thickness. The HxSrCrO3 (HSCO) thin films appear like exfoliated layers which however retain the fully strained state with distorted perovskite structure. Proton doping induces the change of Cr oxidation state from Cr4+ to Cr3+ in HSCO thin films and a transition from metallic to insulating phase. Our investigations suggest an attractive platform in manipulating the electronic phases in proton-based approaches and may offer a potential peeling off strategy for nanoscale devices through low-energy hydrogen plasma implantation approaches.

Dielectric relaxation in ABO3 perovskite oxides can result from many different charge carrier-related phenomena. Despite a strong understanding of dielectric relaxations, a detailed investigation of the relationship between the content of oxygen vacancies (VO) and dielectric relaxation has not been performed in perovskite oxide films. In this work, we report a systematic investigation of the influence of the VO concentration on the dielectric relaxation of Eu0.5Ba0.5TiO3-δ epitaxial thin films. Nuclear resonance backscattering spectrometry was used to directly measure the oxygen concentration in Eu0.5Ba0.5TiO3-δ films. We found that dipolar defects created by VO interact with the off-centered Ti ions, which results in the dielectric relaxation in Eu0.5Ba0.5TiO3-δ films. Activation energy gradually increases with the increasing content of VO. The present work significantly extends our understanding of relaxation properties in oxide films.

Wide bandgap oxide semiconductors constitute a unique class of materials that combine properties of electrical conductivity and optical transparency. They are being widely used as key materials in optoelectronic device applications, including flat-panel displays, solar cells, OLED, and emerging flexible and transparent electronics. In this article, an up-to-date review on both the fundamental understanding of materials physics of oxide semiconductors, and recent research progress on design of new materials and high-performing thin film transistor (TFT) devices in the context of fundamental understanding is presented. In particular, an in depth overview is first provided on current understanding of the electronic structures, defect and doping chemistry, optical and transport properties of oxide semiconductors, which provide essential guiding principles for new material design and device optimization. With these principles, recent advances in design of p-type oxide semiconductors, new approaches for achieving cost-effective transparent (flexible) electrodes, and the creation of high mobility 2D electron gas (2DEG) at oxide surfaces and interfaces with a wealth of fascinating physical properties of great potential for novel device design are then reviewed. Finally, recent progress and perspective of oxide TFT based on new oxide semiconductors, 2DEG, and low-temperature solution processed oxide semiconductor for flexible electronics will be reviewed.

Hybrid carbon-coated transition metal oxides (TMOs@C) offer enhanced lithium storage capabilities, but the facile formation of TMOs@C nanocomposites remains a great challenge. Herein, we report a novel hierarchical hybrid nanostructure of carbon-coated CoFe2O4 twin elliptical frustums (CoFe2O4@C TEFs) via a quick one-pot refluxing reaction in ethylene glycol (EG) followed by an annealing treatment. When evaluated as an anode in lithium-ion batteries (LIBs), the resultant CoFe2O4@C TEF hybrids demonstrate good electrochemical performance with high reversible specific capacity, excellent rate capability and super-long life cycle. After 600 cycles at a current density of 500 mA g−1, the resultant TEFs still deliver a stable reversible discharge capacity of 875 mA h g−1. This work demonstrates the extensive potential of such simple synthetic methods towards various carbon coated transition metal oxide composites for energy conversion and storage devices.

Electrochemical reduction of CO2 to fuels and chemical feedstocks using renewable electricity provides a promising approach toward artificial carbon recycling to address the global challenges in energy and sustainability. The most crucial step for this technique is to develop efficient electrocatalysts capable of reducing CO2 to valuable hydrocarbon products at a low overpotential with high selectivity and stability. In this article, we present a review on the recent developments and understanding of p-block post-transition metal (e.g., Sn, In, Pb, and Bi) based electrocatalysts for electrochemical CO2 reduction. This group of electrocatalysts shows particularly high selectivity for reduction of CO2 to formate or formic acid. Our main focus will be on the fundamental understanding of surface chemistry, active sites, reaction mechanism, and structure–activity relationships. Strategies to enhance the activity including morphology control, nanostructuring, defect engineering, doping, and alloying to modulate the electronic structure will also be briefly discussed. Finally, we summarize the existing challenges and present perspectives for the future development of this exciting field.

Indium oxide is widely used as a transparent electrode in optoelectronic devices and as a photocatalyst with activity for reduction of CO2. However, very little is known about the structural and electronic properties of its surfaces, particularly those prepared under reducing conditions. In this report, directional "lone-pair" surface states associated with filled 5s2 orbitals have been identified on vacuum-annealed In2O3(111) through a combination of hard and soft X-ray photoemission spectroscopy and density functional theory calculations. The lone pairs reside on indium ad-atoms in a formal +1 oxidation state, each of which traps two electrons into a localized hybrid orbital protruding away from the surface and lying just above the valence band maximum in photoemission spectra. The third electron associated with the ad-atoms is delocalized into the conduction band, thus producing the surface electron accumulation layer identified previously on vacuum-annealed In2O3(111) (1 × 1) surfaces. The surface structure is further supported by low-energy electron diffraction, but there is no chemical shift in indium core level X-ray photoelectron spectra between surface In(I) ad-atoms and bulk In(III). The 5s2 lone pairs confer Lewis basicity on the surface In sites and may have a pronounced impact on the catalytic or photocatalytic activity of reduced In2O3.

OBJECTIVE The aim of this study was to evaluate the effects and mechanism of miRNA-31 in synovial cells apoptosis induced by RA. METHODS The miRNA-31 gene expressions were extracted from synovial tissues of normal and RA patients by RT-PCR and H et E staining. The synovial cells of RA patients were isolated and randomly divided into Control, Blank and miRNA groups. The cell apoptosis of difference groups were measured by flow cytometry; the TNF-α and IL-1β concentrations of difference groups were measured by Elisa assay; TLR4 and NF-κB proteins expressions were measured by WB assay and the correlation between TLR4 and miRNA-31 were evaluated by double luciferase target experiment. RESULTS The miRNA-31 gene expression was significantly suppressed in RA tissues (p

A novel ladder-like polymeric silver(I) complex, [Ag2L2] n •2nH2O, where L is 3-aminopyrazine- 2-carboxylate, was obtained by the reaction of 3-aminopyrazine-2-carboxylic acid and silver oxide in aqueous ammonia. The complex was characterized by elemental analysis, IR spectra and single crystal X-ray determination. The smallest repeat unit contains a [Ag2L2] moiety and two water molecules. The Ag•••Ag distance is 3.176(1) A. Each Ag atom is in a Y-shaped coordination, with one carboxylate O and two pyrazine N atoms from two ligands. In the crystal structure of the complex, the dinuclear silver moieties are linked through 3-aminopyrazine-2-carboxylate ligands, to form 1D ladder-like chain along the b axis. The water molecules are linked to the silver chain through hydrogen bonds. There are π•••π interactions between the chains. The complex showed effective cytotoxic property on human lung cancer cell line A549.

Two mononuclear manganese(III) complexes, [MnL1(OH2)(CH3OH)]·ClO4 (1) and [MnL2] (2), where L1 and L2 are the deprotonated forms of N,N′-bis(5-chloro-2-hydroxybenzylidene)ethane-1,2-diamine and tris{2-[(3,5-dichlorosalicylidene)amino]ethyl}amine, respectively, are obtained by the reaction of Schiff bases with manganese perchlorate in methanol. The complexes were characterized by elemental analysis, IR spectra, and single crystal X-ray determination. In both complexes, Mn atoms are in the octahedral coordination. In the crystal structure of complex 1, the complex molecules are linked by water ligands through intermolecular O-H⋯O hydrogen bonds to form dimers. The perchlorate anions are linked to the complex molecules through intermolecular O-H⋯O hydrogen bonds. In the crystal structure of complex 2, the molecules are stacked along the y axis through π⋯π interactions. The catalytic oxidation on olefins of the complexes is studied.

Gas transport in the porous electrode plays a crucial role in the performance of fuel cells. Inthis work, gas convection caused by temperature gradient, typically ignored in the analysis of gastransport in fuel cells, has been evaluated quantitatively. The correlation of gas convection with gas pressure and electrode thickness is investigated systematically. In addition, limiting current density loss caused by temperature gradient and the associated concentration polarization (CP) are evaluated analytically. Our work facilitates a comprehensive understanding of gas transport in electrodes and the improvement in the electrochemical performances of fuel cells.

Slow air transport in the cathodes limits the performance of the metal-air battery. In this work, the diffusion mechanisms in the lithium-air battery have been investigated. It has been found that Knudsen diffusivity can be influenced dramatically by the different pore sizes while bulk diffusivity is almost a constant at a fixed temperature. Limiting current density and concentration polarization, both limited by impeded gas diffusion in the porous cathode, have been evaluated systematically. The analysis of the correlation between those electrochemical parameters and diffusivities improves the quantitative evaluation of gas-based batteries at various materials and operation conditions.

The mixed electronic and ionic conductivity of perovskite oxides has enabled their use in diverse applications such as automotive exhaust catalysts, solid oxide fuel cell cathodes, and visible light photocatalysts. The redox chemistry at the surface of perovskite oxides is largely dependent on the oxidation state of the metal cations as well as the oxide surface stoichiometry. In this study, LaFeO3 (LFO) thin films grown on yttria-stabilized zirconia (YSZ) was characterized using both bulk and surface sensitive techniques. A combination of in situ reflection high-energy electron diffraction (RHEED), X-ray diffraction (XRD), and Rutherford backscattering spectrometry (RBS) demonstrated that the film is primarily textured in the [1 0 0] direction and is stoichiometric. High-resolution transmission electron microscopy measurements show regions that are dominated by [1 0 0] oriented LFO grains that are oriented with respect to the substrates lattice. However, selected regions of the film show multiple domains of grains that are not [1 0 0] oriented. The film was annealed in an ultra-high vacuum chamber to simulate reducing conditions and studied by angle-resolved X-ray photoelectron spectroscopy (XPS). Iron was found to exist as Fe(0), Fe(II), and Fe(III) depending on the annealing conditions and the depth within the film. A decrease in the concentration of surface oxygen species was correlated with iron reduction. These results should help guide and enhance the design of LFO materials for catalytic applications.

Two mononuclear manganese(III) complexes, [Mn(L)(NCS)] (I) and [Mn(L)(OH2)2] · Hfac · H2O (II), where L is the deprotonated form of N,N′-bis(5-fluoro-2-hydroxybenzylidene)ethane-1,2-diamine, Hfac is hexafluoroacetylacetonate, were prepared and characterized by elemental analysis, IR spectra and single crystal X-ray determination (CIF files CCDC nos. 1008309 (I), 1008310 (II)). The Mn atoms in both complexes are in octahedral coordination. Complex I crystallized in orthorhombic space group Pbca with unit cell dimensions a = 12.4090(4), b = 13.5432(5), c = 19.4637(7) A, V = 3271.0(2) A3, Z = 8, R1 = 0.0423, wR2 = 0.0922. Complex II crystallized in triclinic space group \(P\bar 1\) with unit cell dimensions a = 7.6845(3), b = 88.984(2), c = 13.5522(7) A, α = 78.369(1)°, β = 88.984(2)°, γ = 83.835(1)°, V = 1237.63(9) A3, Z = 2, R1 = 0.0526, wR2 = 0.1421. In the crystal structure of I, the complex molecules are stack via π⋯π interactions along the y axis. In the crystal structure of II, the molecules are linked through intermolecular O-H⋯O hydrogen bonds, to form chains along the x axis. The catalytic oxidation on olefins of the complexes was studied.

Reasonably fabricating ordered structures of ionic polymers is very important for the development of novel func- tional materials. By combining the ions and liquid cry stalline polymer, we successfully designed and synthesized a series of novel combined main-chain/side-chain ionic liquid crystalline polymer (MCSC-ILCPs) containing imidazolium groups and different counter-anions, poly (2,5-bis{(6-(4-butoxy-4!-imidazolium biphenyl)hexyl)oxycarbonyl}styrene salts) poly(BImBHCS-X) with the following types of counter-anions (Br", BF4", PF6" and TFSI"). Combined technologies con- firmed the chemical structures of the monomers and polymers with imidazolium cation and different counter-anions. Dif- ferential scanning calorimetry (DSC), polarized light microscopy (PLM) and one- and two-dimensional wide-angle X-ray diffraction (1D and 2D WAXD) results illustrated that the LC structures and the transitions of ordered structures depended on the nature of the counter-anion employed. The polymers with Br" and BF4" counter-anions exhibited smectic A (SmA) LC behavior below the isotropic temperature. The another one, poly(BImBHCS-TFSI) with the large volume of the TFSI" anion destroyed the packing of the LC ordered structure resulting in an amorphous structure. The photophysical properties of the polymers prepared can be adjusted by tuning the ionic interaction of the polymers by switching the counter-anion.

Inefficient gas transport in the porous cathode is disastrous for the lithium–air battery to achieve a high electrochemical performance. Previous evaluation of the cathode diffusivity relies on indirect calculations based on multiple V–I data obtained over the intact battery system, which inevitably induces evaluation uncertainty and material waste. In this report, an electrochemical device is designed for the out-of-cell diffusivity measurement in the lithium–air battery with micro/nano-sized cathodes. With the measured diffusivity, a few electrochemical parameters including the limiting current density and the concentration polarization associated with the porous cathodes can thus be directly evaluated. The work facilitates the development of highly-efficient cathode materials in the general field of metal–air battery field.

Oriented attachment (OA) growth has been a promising method for the synthesis of one dimensional (1D) anisotropic nanocrystals (NCs). An unresolved fundamental issue is to understand the growth mechanism at the initial stage of an OA nanorod (NR) growth. In this report, a collision–recrystallization model is proposed to investigate the initial OA growth of NRs. The repulsive electrical double layer (EDL) interaction and the attractive van der Waals (vdW) interaction at the initial OA stage are derived by the accurate surface element integration (SEI) technique and the classical Hamaker equation, respectively. Our results show that the self-recrystallization of nanochains increases the collision activation energy of NPs dramatically as their surface potentials and Hamaker constants increase. Under a specific electrolyte concentration, the collision activation energy reaches the maximum, indicating that the growth rate of OA can be controlled by adjusting the electrolyte concentration.

The development of diabetic peripheral neuropathy (DPN) is always followed by changes in vascular endothelial cells that are related to the reactivity of the homocysteine (Hcy) sulfhydryl group. In this meta-analysis, we investigated the association of Hcy with the pathogenesis and progression of DPN. We screened the Embase, Ovid, PubMed, Web of Science, Wangfang, and China National Knowledge Infrastructure databases. All analyses were performed by using the STATA software, version 12.0 (StataCorp, College Station, TX, USA) and the Comprehensive Meta-analysis 2.0 software (Biostatic Inc., Englewood, NJ, USA). The standardized mean difference (SMD) and 95% confidence interval (95%CI) were further calculated. The electronic literature search identified six articles that included 603 patients with DPN and 687 healthy controls. The pooled SMD of those six studies revealed that increased serum levels of Hcy may be correlated with DPN (SMD = 1.23, 95%CI: 1.09-1.36, P < 0.001). Subgroup analysis according to ethnicity indicated that high serum Hcy levels might be an important risk factor for DPN in both Asian and Caucasian populations (Asians: SMD = 0.62, 95%CI: 0.45-0.79, P < 0.001; Caucasians: SMD = 2.32, 95%CI: 2.10-2.55, P < 0.001; respectively). Elevated serum levels of Hcy indicate the risk of development of DPN in patients, suggesting that Hcy levels could be used as a marker for new therapeutic approaches to DPN.

The aim of the present study was to study the effects of arachidonic acid (ARA) in a rat brain ischemia/reperfusion model induced by middle cerebral artery occlusion (MCAO). A total of 50 rats were randomly divided into five groups: control group, MCAO group, MCAO + ARA 0.3 g/kg group, MCAO + ARA 1 g/kg group, and MCAO + ARA 3 g/kg group. The MCAO + ARA groups received ARA by intraperitoneal injection daily for 14 consecutive days, while the rats in the control and MCAO groups were given equivalent volume of saline. We detected the Morris water maze test and pathological changes to investigate the ischemia/reperfusion injury. The protein levels of tumor necrosis factor-alpha and interleukin-6 in the hippocampus were detected by enzyme-linked immunosorbent assay kits. In addition, the activities of superoxide dismutase, glutathione peroxidase, and malondialdehyde were assayed in hippocampus homogenates to evaluate the oxidative stress after ischemia/reperfusion. The results indicated that ARA administration decreased biochemical parameters of inflammation and oxidative stress. Morris water maze test and histopathological examination further verified the protective effects of ARA on ischemia/reperfusion injury rats. These findings demonstrated that ARA could protect MCAO-induced brain injury rats by inhibition of inflammation and oxidative stress, suggesting that it may have potential as a therapy for cerebral ischemia/reperfusion injury.

Carbon innercoated ordered porous TiO2 were prepared by anodic oxidation of pure titanium sheets, followed by in situ decomposition of glucose in the TiO2. Structure, morphology, and electrochemical properties of the composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and a variety of electrochemical testing techniques. Initial discharge capacity and cycling performance of ordered porous TiO2 were improved dramatically by the inner carbon coating. Migration of Li ions and electrons in the carbon layer was beneficial to suppress the charge transfer resistance of TiO2 electrode, which resulted in significant improvement in electrochemical performances.

The diffusion rate of oxygen has a significant impact on the power density, rate capacity, discharge capacity, and electrolyte stability of lithium–air batteries (H.-G. Jung, J. Hassoun, J.-B. Park, Y.-K. Sun, B. Scrosati, Nat. Chem. 2012, 4, 579–585; J. Read, K. Mutolo, M. Ervin, W. Behl, J. Wolfenstine, A. Driedger, D. Foster, J. Electrochem. Soc.­ 2003, 150, A1351–A1356; Y. Cui, Z. Wen, X. Liang, Y. Lu, J. Jin, M. Wu, X. Wu, Energy Environ. Sci.­ 2012, 5, 7893–7897). Oxygen diffusivity in the solid porous cathodes of gas-based batteries is typically obtained by employing a few electrochemical models. In addition to the indirect computing characteristic, previous methods of evaluating oxygen diffusivity require multiple voltage–current experiments over intact lithium–air batteries, and can cause unnecessary costs resulting from the waste of materials from other battery components (J. Read, J. Electrochem. Soc. 2006, 153, A96–A100). In this report, through derivation and analytical design, a methodology is proposed for the direct out-of-cell oxygen diffusivity measurement in lithium–air batteries. The proposed electrochemical devices allow for efficient diffusivity measurements in porous solid cathodes, as well as subsequent quantitative pre-evaluation of important battery parameters including electrode porosity, thickness, and tortuosity. The proposed methodology is expected to facilitate the development of low-cost battery systems for a variety of applications, such as large-capacity automobile batteries and electronics.

A kind of core shell cathode material, Li1·2(Mn0·54Co0·13Ni0·13)O2@AlF3/C (LMSAC) was prepared by coating AlF3 and carbon hybrid layer on the surface of lithium rich manganese based solid solution (LMSS) through a sol–gel process. It was characterised by X-ray diffraction (XRD) patterns, scanning electron microscope (SEM) and transmission electron microscope (TEM). Its electrochemical properties were evaluated by electrochemical impedance spectra and galvanostatic charge–discharge measurements. Owing to the AlF3/C shell, the LMSAC could deliver the initial capacities of 278, 260, 246, 230 and 210 mAh g−1 at the rates of 0·1, 0·2, 0·5, 1 and 2C in the potential range of 2–4·8 V (versus Li+/Li) respectively, exhibiting an excellent rate capability. The corresponding coulombic efficiencies are 90, 89, 87, 88 and 85% in the first cycle. After cycled at the 0·1C and 1C rates for 50 times, the LMSAC remains 97 and 96% of the initial capacities respectively, displaying an enhanced cycling performance. The result...

A reduction in Ohmic, activation and concentration-polarization losses is of paramount importance in improving the efficiency of solid oxide fuel cells, proton-exchange-membrane fuel cells, and molten-carbonate fuel cells. Efficient measurements of gas diffusivities at the operating conditions of fuel cells allow concentration polarization losses of these fuel cells to be reliably evaluated. To enhance the applicability of solid oxide fuel cells, tremendous work on the development of gas diffusion models and gas diffusivity measurement techniques have been done to pre-evaluate the concentration polarization losses of fuel cells. This review focuses on the recent advancement of gas diffusion models and diffusivity measurement techniques of solid oxide fuel cells. The review seeks to provide an insightful guidance for designing high-performance solid oxide fuel cell electrodes with efficient thickness, porosity, among other parameters.

Highly aligned one-dimensional (1D) nanorods of the transparent conducting oxide In(2)O(3) have been grown on (110)-oriented Y-stabilized ZrO(2) substrates, whereas growth on (100) and (111) substrates leads respectively to blocklike 3D islands and continuous films. It is shown that the striking influence of substrate orientation on the growth morphology is controlled by differences in energies between the low index surfaces of In(2)O(3) and that spontaneous self-organization is driven by minimization of surface energies.

Photoemission spectra of Sn-doped In 2O 3(111) have been measured using a range of photon energies between 40 and 1300 eV. The intensity of structure at the bottom of the valence band associated with states of mixed Sn 5s/O 2p character increases with increasing photon energy relative to that of states of more dominantly O 2p character at the top of the valence band, as expected from one electron ionisation cross sections. In addition a pronounced resonance in the intensity of a weak conduction band feature is observed around the In 4p core threshold. © 2011 Elsevier Ltd. All rights reserved.

Surface structure and electronic properties of In20 3(111) single-crystal thin films grown on V-stabilized Zr0 2(1 11) was observed. The surface geometrical structure was examined by atomic force microscopy (AFM), scanning tunneling microscope (STM) and low electron energy diffraction (LEED). The surface structure, however, provides in turn the essential basis for understanding the surface electronic properties such as the band offset, which plays an important role in determining the potential performance and stability of devices. The examination of valence band and conduction band spectra by HXPS adds further weight to the conclusion that the electron accumulation at the surface is an intrinsic property of In 2O3.

Europium chalcogenides (EuX, X = O, S, Se, Te), a class of prototypical Heisenberg magnetic semiconductors, exhibit intriguing properties in optics, magnetism, and magneto-optics at the nanoscale, and have broad application potential in optical/magnetic sensors, spintronics, optical isolators, etc. EuX nanocrystals (NCs) exhibit enhanced properties, such as high saturation magnetization, a strong magneto-optic effect (Faraday rotation), and high magneto resistance, which are all unanimously dependent on the NC's size, shape, and surface information. In this report, we give an overview of the fundamental properties of bulk EuX, and illustrate the quantum confinement effects on the optical, magnetic and magneto-optical properties of EuX nanostructures. We then focus on doping and self-assembly-two efficient methods that enhance magnetic properties by manipulating magnetic coupling in EuX nanostructures. In particular, we look towards future research on Eu(2+) NCs, which along with the overview provides an up-to-date platform for evaluating the fundamental properties and application potential of Eu-based semiconductors.

Bioactive guided tissue regeneration (GTR) membrane has had some success for periodontal therapy. In this study, poly(lactic-co-glycolic acid) (PLGA)/multi-walled carbon nanotubes (MWNTs) composite membranes were incu- bated in three supersaturated calcification solutions (SCS) of different pH values for 21 days to prepare a PLGA/ MWNTs/apatite composite. Scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy dispersive spectroscopy (EDS), water contact angle measurement and mechanical testing were used for characterization. It was found that after 21 days incubation, apatite with low crystallite size and crystallinity was formed on the PLGA/MWNTs composite membranes. The Ca-poor carbapatite was similar in morphology and compo- sition to that of natural bone. The size and shape of the apatite crystals immersed in three SCS were different from each other. The hydrophilicity and mechanical properties of the PLGA/MWNTs composite membranes were significantly enhanced after mineralization. This indicated that biomimetic mineralization may be an effective method to improve the biocompatibility and bone inductivity of certain materials. The PLGA/MWNTs/apatite composites may be potentially use- ful in GTR applications, particularly as GTR membranes for periodontal tissue regeneration.

In order to study the reducing and reusing of petrochemical residual sludge and solve the technical problem of traditional anaerobic digestion, the contrast research was carried out between the mesophilic (30°C) and thermophilic (60°C) anaerobic digestion. The result showed that the efficiency of thermophilic digestion was twice as big as that of mesophilic digestion. When sludge dosage increased, the concentration of volatile fatty acid rose sharply and pH value decreased correspondingly. When the reaction became stable, the concentration of volatile fatty acid began to drop and the corresponding pH value began to rise gradually. At each sludge dosage, alkalinity dropped first and then increased with the reaction carried on. In a different sludge dosage, the fluctuation of pH, volatile fatty acid, and alkalinity under the thermophilic condition was less than that under the mesophilic condition by a different sludge dosage. Through the experiment of sludge digestions, the optimizing technical con...

The influence of the substrate temperature on the epitaxial growth of In2O3 on Y-stabilized ZrO2(1 1 1) by oxygen plasma assisted molecular beam epitaxy has been investigated over a range between 550 and 860 °C. In all cases the films grow with (1 1 1) planes of the epilayer parallel to those of the substrate. Films grown at low temperature (T

The deposition of 1/3 of a monolayer of Bi on Ag(111) leads to the formation of BiAg2 surface alloy with a long range ordered 3 × 3 R 30 ∘ superstructure. A detailed analysis of this structure using LEED I–V measurements together with DFT calculations is presented. We find strong correlation between experimental and calculated LEED I–V data, with the fit between the two data sets having a Pendry's reliability factor of 0.16. The Bi atom is found to replace one top layer Ag atom in each unit cell, forming a substitutional BiAg2 surface alloy, with the Bi atoms residing approximately 0.6 A above the Ag atoms due to their size difference. DFT calculations are in good agreement with the LEED results.