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ZrO 2 -based catalysts doped with Y were prepared by co-precipitation method. The effect of yttrium modification on the selective conversion of bio-ethanol to propylene over ZrO 2 catalysts was investigated. The physical and chemical properties of the catalysts were characterized by N 2 adsorption-desorption method, temperature programmed desorption and X-ray diffraction. The maximum yield of propylene reached 44.0% over 0.03Y/ZrO 2 catalyst. A coordination of acid-base properties accounts for the remarkable improvement of reaction activities over Y-doped ZrO 2 catalysts in this investigation. On the basis of calculation results, it can be concluded that significant charge transfer occurs as a result of introduction of Y or O-vacancy. The adsorption of ethanol and propylene on perfect t-ZrO 2 (1 0 1), defect t-ZrO 2 (1 0 1) and Y/ZrO 2 (1 0 1) surfaces were investigated with density functional theory (DFT). The adsorption for ethanol on Y/ZrO 2 (1 0 1) and defect t-ZrO 2 (1 0 1) surfaces are more stable than that on perfect t-ZrO 2 (1 0 1). On the defect t-ZrO 2 (1 0 1) surface, ethanol dominantly absorbs at the O-vacancy site, indicating that O-vacancy becomes the favorable adsorption site. On the Y/ZrO 2 (1 0 1) and defect t-ZrO 2 (1 0 1) surfaces, the adsorption energy of propylene decreases, which makes propylene desorb quickly after formation. [ABSTRACT FROM AUTHOR]

The corrosion protection of chromium coating deposited on aerospace bearing steels by using the Filtered Cathodic Vacuum Arc deposition- Metal Evaporation Vacuum Arc duplex technique (MEVVA-FCVA) had been investigated. The protection efficiency of chromium coating on different substrate materials had also been evaluated. The chromium coating was mainly composed of nanocrystallineα-Cr in a range of 50–200 nm. The orientation distributions of α-Cr film on substrates with different composition had a certain difference to each other. Electrochemical experimental results indicated that the chromium coating significantly improved the corrosion resistance of experimental bearing steels in 3.5% NaCl solution. The protective efficiency of chromium films were all over 98%. The corrosion resistance of chromium coating was influenced by the chemical composition of substrate material. The chromium coatings on higher Cr-containing substrate displayed lower corrosion current density and more positive corrosion potential. The increase of passive film thickness and the formation of a mass of chromium oxide and hydroxide on the surface are responsible for the improved corrosion properties. [ABSTRACT FROM AUTHOR]

The photocatalysis behavior of TiO 2 nanosheet array films was studied, in which the ratio of bulk/surface defects were adjusted by annealing at different temperature. Combining positron annihilation spectroscopy, EPR and XPS, we concluded that the bulk defects belonged to Ti 3+ related vacancy defects. The results show that the separation efficiency of photogenerated electrons and holes could be significantly improved by optimizing the bulk/surface defects ratio of TiO 2 nanosheet films, and in turn enhancing the photocatalysis behaviors. [ABSTRACT FROM AUTHOR]

The aerospace bearings steel CSS-42L was ion implanted by carbon with implantation fluxes of 5 × 10 16 ions cm −2 . The composition, microstructure and hardness of the carbon implanted samples were characterized using X-ray photoelectron spectroscopy, Auger electron spectroscopy, X-ray diffraction, and nanoindentation tests. The corrosion and tribological properties were also evaluated in the present work. The results shown that carbon implantation produced an amorphous layer and graphitic bounds formed at the near surface of CSS-42L steel. In the electrochemical test, the carbon implanted samples suggested lower current densities and corrosion rates. Carbon ion implanted samples shown a relative Cr-enrichment at the surface as compared with nonimplanted samples. The improved corrosion resistance is believed to be related to the formed amorphous layer, the enhancement of Cr diffusion in the carbon implantation layer which contributed the formation of passive film on the surface, the decrease of free electrons which caused by the increase of carbon fraction. The external hard layer had positive effect on the wear resistance, reducing strongly the friction coefficient about 30% and the abrasive-adhesive mechanism present in the unimplanted samples was not modified by the implantation process. [ABSTRACT FROM AUTHOR]

Organometal halide perovskite materials are emerging as solar cell materials, but the understanding of its performance is not yet enough, especially in its ferroelectricity which is important for the separation of photo-generated carriers. In this paper, we report investigations on influences of annealing temperature on the ferroelectricity of solution-processed methylammonium lead triiodide (CH 3 NH 3 PbI 3 ) thin film. It is found that annealing temperature has significant effect on the crystallinity and the crystal size, which further affects the ferroelectricity and the luminescence property. It indicates that the crystallization degree of the thin film and the uniformity of crystal growth are gradually getting better, and the phase contrast of positive polarization areas and negative polarization areas are gradually strengthened. [ABSTRACT FROM AUTHOR]

• (Ti + C) ions co-implantation into the Cr-coated CSS-42L bearing steel was studied. • Ion implantation facilitated the formation of ceramic phases and amorphous phase on the near surface. • Corrosion resistance and mechanical properties of Cr film after co-implantation were greatly improved. In this work, the effects of (Ti + C) co-implantation on the corrosion resistance and mechanical properties of Cr-coated CSS-42L bearing steel were described. Single Ti and C ion implantation were also applied for comparison. The corrosion behavior and mechanical properties of implanted samples were investigated by nanoindentation and potentiodynamic polarization tests. Film structures and phase transitions had been characterized by GAXRD, AES, XPS, SEM and TEM. The current density and corrosion rate of Cr-coated CSS-42L bearing steel after ion implantation were reduced obviously, especially for (Ti + C) co-implanted samples which were more than 10 times lower than that of the untreated samples. It was also noticed that the Young's modulus of Cr coating after (Ti + C) co-implantation decreased, meanwhile its nanohardness improved significantly. The corrosion resistance and mechanical improvement were attributed to the formation of irradiated amorphous phase and ceramic phases Cr 2 C/TiC. [ABSTRACT FROM AUTHOR]

The specific capacity of lithium-ion batteries (LIBs) is one of the key challenge, which determines the performance in practical devices. Here, we explored that multi-active centers of electrode materials will significantly boost the Li storage capacity. Based on the comprehensive first-principles calculations of NiPS 3 monolayer, our results show that Li atom can be strongly adsorbed on Ni and S atoms, which provides the possibility of multi-adsorption of Li atoms. Significantly, the lowest energy barrier of Li diffusing on NiPS 3 monolayer is only 0.279 eV, benefiting the ultrafast charging/discharging process. Moreover, the estimated open circuit voltage is about 0.55 eV, implying NiPS 3 monolayer as a suitable anode material for LIBs. Importantly, the calculated theoretical specific capacity of NiPS 3 monolayer is about 608 (mA h)/g, which is almost the highest value among two-dimensional transition-metal compounds. Thus, our results clearly show that creating multi-active sites in transition-metal compounds has great promise for developing anode materials of high-performance LIBs. Unlabelled Image • We firstly demonstrated that the specific capacity of Li ion batteries can be boosted with multi-active centers. • The calculated diffusion barrier for Li is around 0.279 eV, and the average intercalation potential is about 0.55 V. • NiPS3 monolayer exhibits a very high Li storage capacity, namely, 608 (mA h)/g. [ABSTRACT FROM AUTHOR]

[Display omitted] • High-quality graphene prepared by electrochemical exfoliation. • Modification of graphene with dopamine. • Construction of PGF using metal ion-assisted gelation pathway. • The unidirectional freezing enables the foam to have a vertically aligned structure. • PGF/EP composite exhibits high thermal conductivity and excellent electrical insulation. Although graphene has aroused considerable interest in the thermal conductive enhancement of polymer composites for its superb intrinsic thermal conductivity, the enhancement efficiency is still limited by its production-induced defects, misalignment and intense phonon interface scattering. Herein, the three-dimensional (3D) polydopamine-graphene foam (PGF) with high orientation and good interfacial bonding has been prepared by electro-exfoliation, surface modification and unidirectional-freezing. This unique structure imparts excellent thermal conductivity, electrical insulation and good mechanical property to the PGF/epoxy (PGF/EP) composite. The highly arranged and compact stacked PDA-graphene sheets bound by metal ions provide heat conduction paths for effective phonon transport within the matrix. The manufactured PGF/EP shows enhanced through-plane thermal conductivity of 3.48 W/m·K with 3.02 vol% of PGF, excellent surface & volume electrical resistivity (2.7 × 1011 Ω and 1.65 × 1011 Ω·cm) and high mechanical strength (82.74 MPa), as well as the outstanding heat dissipation performance. Therefore, the PGF/EP composites prepared in the present study have a broad application prospect in advanced electronic packaging materials. [ABSTRACT FROM AUTHOR]

Schematic illustration of the energy band positions of h-WO 3 and o-WO 3 ·H 2 O showing the internal electric field from h-WO 3 (+) to o-WO 3 ·H 2 O (−), and the possible Z-scheme carriers transfer mechanism for 4CP degradation. [Display omitted] • Co-grown preparation method is effective in building chemical bonds at heterophase junctions. • 26 h/o-WO 3 has less-defective and low lattice mismatching interface. • The -W-O-W- "bridge" acts as electron transfer channel for building internal electric field at h-WO 3 /o-WO 3 ·H 2 O interface. • Up to 2.5 e electrons migrate from h-WO 3 to o-WO 3 ·H 2 O to form a strong internal electric field at their interface. Surface defect states and lattice mismatch are two most crucial problems to be resolved in hetero-interface photocatalysts design for achieving highly efficient photocatalytic performance. Co-grown interfacial regulation strategy has been pointed out in this work as a feasible way for fabrication interatomic junction with less-defective and abrupt interface. By simply hydrothermal step, the selected model 26 h/o-WO 3 hetero-phase junction with outstanding interface structure is prepared. Two constituents of 26 h/o-WO 3 , h-WO 3 and o-WO 3 ·H 2 O connect to each other though consecutive -W-O-W- chemical bonds with 0.058 lattice mismatching at their interface. This novel 26 h/o-WO 3 interatomic junction exhibits superior photocatalytic activity for the degradation of Tetrachlorophenol as compared with its comparative 26 h/o-WO 3 (L) prepared by loading method, as well as pristine h-WO 3 and o-WO 3 ·H 2 O. Investigations on the charge dynamics and carriers separation mechanism demonstrate that the superior photocatalytic activity mainly results from the synergistic effects of ultrafast carrier transport, and great driving force from internal electric field formed though consecutive chemical bonds at interface. This work provides a facile way to develop interatomic junction showing great internal electric field for boosting photocatalytic activities. [ABSTRACT FROM AUTHOR]