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In order to determine if there are curlings along other directions than [100] and [010] in kaolinite (Kaol) layer, 1 nm Kaol hydrate with 85% yield was synthesized by the fluorine-free method. Its structure and morphology were investigated by X-ray diffraction (XRD), field emission transmission electron microscopy (FETEM) and selected area electron diffraction (SAED). The results show that: (1) there are not only single curling and two opposite parallel curlings, but also two adjacent curlings with about 120° angle in one single layer; (2) there are four new orientations of curlings [ 1 1 ¯ 0 ], [110], [310] and [ 3 1 ¯ 0 ] in Kaol hydrate. The reasons that Kaol layers can curl along multiple directions may be that: first, two types of incompatible matchings between tetrahedrons and octahedrons; second, the hexagonal distribution and the zigzag distribution of two types of matchings. [ABSTRACT FROM AUTHOR]

Abstract: The laser-induced damage of Ta2O5 films annealed at a wide range of temperature (473–1273K) at the laser wavelengths of 1064 and 355nm was investigated. The relations between microstructure, optical properties, chemical composition, absorption and laser-induced damage threshold (LIDT) were studied. The dependence of a damage mechanism on laser wavelengths was discussed. It was found that the LIDT either at 1064 or 355nm first increased and then decreased with increase of annealing temperature. The LIDT at 1064nm was influenced by the substoichiometric defects, structural defects and thermal diffusion, whereas at 355nm it was affected mainly by the intrinsic absorption and structural defects. Both the maximum LIDT at the two wavelengths were obtained at the annealing temperature of 873K, which could be attributed to the lowest defect density in films. [Copyright &y& Elsevier]

Abstract: Ta2O5 films were deposited on BK7 substrates by e-beam evaporation with different deposition parameters such as substrate temperature (323–623K), oxygen pressure (0.5–3.0×10−2 Pa) and deposition rate (0.2–0.5nm/s). Absorption, scattering and chemical composition were investigated by surface thermal lensing (STL) technique, total integrated scattering (TIS) measurement and X-ray photoelectron spectroscopy (XPS), respectively. The laser-induced damage threshold (LIDT) was assessed using pulsed Nd:YAG 1064nm laser at a pulse length of 12ns. The results showed that optical properties, absorption and LIDT were influenced by the deposition parameters and annealing. However, scattering was little correlated with the deposition parameters. On the whole, the LIDT increased with increasing substrate temperature and oxygen pressure, whereas it increased firstly and then decreased upon increasing deposition rate. After annealing at 673K for 12h, the LIDT of films improved significantly. The dependence of possible damage mechanism on deposition parameters was discussed. [Copyright &y& Elsevier]

Deformation of constituent phases determines the mechanical properties of titanium alloys. To address this relationship, the deformation of primary α (α p ), secondary α plates (α s ) and residual β phase (β r ) in Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy was investigated based on the microstructure near fracture surface of uniaxial tensile samples. It is found that α p is elongated and α s mainly undergoes kinking deformation during tensile tests. The deformation of α p is dominated by planar slipping, the deformation of α s in colony is dominated by planar slipping and in basket weave is controlled by twin, planar slipping and dislocation tangling and the deformation of β r is controlled by dislocation tangling. In the microstructure with high volume fraction of α p (about 60%), the deformation amount of both α p and α s increases with the thickness of α s , which increases the elongation of the alloy and changes the failure modes of α p from fracture to boundary separation. In the microstructure with low volume fraction of α p (19%) and long α s , α p has large deformation amount, while α s with relative small deformation amount has large kinking region which increases the strength of the alloy. However, due to low volume fraction of α p , its contribution to the ductility of alloy is limited and thus the elongation of the alloy is relatively small. [ABSTRACT FROM AUTHOR]

De-intercalation is the inverse of the intercalation process, which can be easily and rapidly determined by thermal analysis. Research on the de-intercalation process is beneficial to exploring the intercalation mechanism that is still unclear in the case of kaolinite intercalation. The objectives of this study were (a) to investigate the thermal decomposition behavior of the intercalation compound of kaolinite and (b) to determine the kinetics of de-intercalation process by thermal analysis to study the mechanism of de-intercalation reaction in kaolinite. Here, the kaolinite–acetamide intercalation compound that was prepared by the direct intercalation method was investigated. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy results showed that acetamide molecules were inserted into the interlayer space of kaolinite and apparently formed new hydrogen bonds with the inner surface hydroxyl groups of kaolinite. The basal spacing of kaolinite increased from 0.721 to 1.102 nm upon intercalation with acetamide. The thermogravimetric (TG) and differential scanning calorimetry (DSC) curves indicated that the decomposition process of the intercalation compound could be divided into two steps. The first step was attributed to the de-intercalation of the intercalated molecules at a temperature of about 181 °C, and the second step corresponded to the dehydroxylation of kaolinite at a temperature of about 502 °C. The completed kinetic triplet of the de-intercalation reaction was obtained through thermal analysis kinetics methods. The apparent activation energy E a of the de-intercalation process was calculated to be about 73.6 kJ mol − 1 by an iterative procedure. The pre-exponential factor A was estimated to be in the range of 1.06 × 10 10 s − 1 to 7.92 × 10 10 s − 1 by the Dollimore method. The optimized mechanism function of the de-intercalation process of acetamide was determined to be an n th-order chemical reaction through the Malek method. The mechanism function is G ( α ) = [1 − (1 − α ) 1 − n ] / (1 − n ), f ( α ) = (1 − α ) n and experiments showed that the value of n increased with increased heating rate. [ABSTRACT FROM AUTHOR]

The humidity sensors based on metal halide perovskite have achieved outstanding improvement. However, there are few reports of perovskite nanocrystals for humidity sensors. Herein, CsPdBr3 nanocrystals with high surface‐to‐volume ratio are synthesized by the in situ spin‐coating method. Subsequently, the humidity sensor based on CsPdBr3 nanocrystals is prepared and the response mechanism is demonstrated to originate from the formation of the Pd––O bond on the surface by performing density functional theory calculation. The humidity sensor shows a fast response/recovery time of 0.68/2.43 s in a relative humidity range from 88.9%RH to 4.7%RH; the fast response/recovery properties are used to monitor human respiratory and noncontact switch. Moreover, the hydromechanical characteristics of unsaturated soil are obtained by noncontact testing with the humidity sensor for the first time in geological engineering, and the strong correlation between relative humidity and hydromechanical characteristics is revealed by mathematical derivation, which lays the theoretical foundation for the noncontact real‐time sensing of hydromechanical characteristics of unsaturated soil. These findings not only open the door to the development of perovskite nanocrystals materials for humidity measurement, but also offer a new method for nondestructive and real‐time test of the mechanical properties of soil in geological engineering. [ABSTRACT FROM AUTHOR]

Highlights: [•] Excitonic energies from ZnO related MQW were dependent on both the thicknesses of well and barrier layers. [•] The correlation between the exciton energies and the barrier thicknesses could be fitted by the well-known Arrhenius formula. [•] The calculation results show a good agreement with the experimental data obtained from PL spectra. [ABSTRACT FROM AUTHOR]

Abstract: We make a comparison on the photoluminescence (PL) from the Mg0.1Zn0.9O film and ZnO nanoflakes (NFs) over the range of 10–300 K. It is clear that their PL spectra are dominated by the radiative recombination of localized or bound excitons at 10 K. As the temperature increases, these excitons are gradually converted toward free excitons (FX) or annihilate through a thermal dissociation/activation or a non-radiative recombination channel. In addition, it is found that the quenching behavior of integrated PL intensity exhibit two activation energies in the different temperature ranges for the NFs, suggesting that a re-localization of FX might occur during the range of 70–300 K. [Copyright &y& Elsevier]

Abstract: A broad band polarization independent reflector working in the telecommunication C+L band is proposed using the guided mode resonance effect of periodic three-level silicon-based element. It is shown from our calculations that this structure can provide high reflection (R>99.8%) and wide angular bandwidth (θ≈8°, R>99.5%) for both TE and TM polarizations over the wide spectrum band 1.5–1.6μm. Furthermore, it is found with Rigorous Coupled Wave Analysis (RCWA) that the extremely wide band property for both TE and TM polarizations is due to the simultaneous excitation of strong modulation guided modes in the design wavelength range. [Copyright &y& Elsevier]

Abstract: Vertically aligned TiO2 nanorod (NR) arrays have been grown on the fluorine doped tin oxide (FTO) substrates by hydrothermal methods and the structures were employed to fabricate the dye-sensitized solar cells (DSSCs). The charge transport properties were investigated by the current to voltage curves and the electrochemical impedance spectroscopy. It was found that DSSCs containing the as-prepared and 500°C annealed TiO2 NRs exhibit different trends with the growth time (t). The DSSCs assembled with the un-sintered NR arrays showed the highest power conversion efficiency (η) of 1.87%. When DSSCs were assembled with the sintered NR arrays, nearly 400% enhanced efficiency were obtained, and the values (η) showed a positive correlation with t. This behavior may be attributed to the improved adhesion and electric contact between TiO2 and FTO, as well as the reduced number of recombination sites. [Copyright &y& Elsevier]

Abstract: Bulk nanocrystalline Cu with an average grain size of 33nm, a strong {200} texture and a narrow grain size distribution was produced by pulse electrodeposition. Tensile tests on this material indicated a combination of high yield strength (624MPa), limited tensile elongation (<5%) and enhanced strain rate sensitivity (0.029). Deformation mechanisms were discussed with strain rate sensitivity and activation volume under analytical models from the literature. Overall, the plastic deformation of the nanocrystalline Cu was dominated by dislocation processes, while grain boundary activities were also involved especially at the lowest strain rate. Analysis on the fracture surfaces revealed a brittle feature. [Copyright &y& Elsevier]

Abstract: A broad band polarization independent reflector working in the telecommunication C+L band is proposed with using the guided mode resonance effect of periodic fused silica grating deposited by a layer of germanium medium. It is shown from our calculations that this structure can provide high reflection (R >98%) and wide angular bandwidth (θ ≈4°, R >98%) for both TE and TM polarization over wide spectrum band 1.5–1.6μm. Furthermore, it is found with rigorous coupled wave analysis (RCWA) that the extremely wide band property for both TE and TM polarization is due to the simultaneous excitation of strong modulation guided modes in the design wavelength range. [Copyright &y& Elsevier]

In this work, nickel sulfide (NiS)/bismuth oxybromide (BiOBr) hybrids were synthesized by a two-step hydrothermal method. Some advanced tools were employed to characterize the crystal phase, morphological evolution, light absorption and photocatalytic performance. Significantly, NiS/BiOBr hybrids exhibited enhanced photocatalytic activity toward rhodamine B (RhB) degradation under visible light irradiation. Comparatively, NS/BOB-3.0 showed the highest degradation rate, over 2.5 times higher than that of pure BiOBr. Furthermore, the retarded recombination rate of photogenerated carriers contributed to the improved photocatalytic performance. The results indicate that hybrids may be a promising method for enhancing the photocatalytic ability of BiOX-based semiconductor. [ABSTRACT FROM AUTHOR]

Highlights: A hybridized mechanical and solar energy-driven hydrogen production system was developed. A rotatory disc-shaped triboelectric nanogenerator (RD-TENG) enables to harvest mechanical energy from water flow and functions as a sufficient external power source. WO3/BiVO4 heterojunction is fabricated as photoanodes in the self-powered photoelectrochemical (PEC) cell, and the hydrogen production rate reaches to 7.27 μL min−1 under sunlight illumination with the energy conversion efficiency of 2.59%.Photoelectrochemical hydrogen generation is a promising approach to address the environmental pollution and energy crisis. In this work, we present a hybridized mechanical and solar energy-driven self-powered hydrogen production system. A rotatory disc-shaped triboelectric nanogenerator was employed to harvest mechanical energy from water and functions as a sufficient external power source. WO3/BiVO4 heterojunction photoanode was synthesized in a PEC water-splitting cell to produce H2. After transformation and rectification, the peak current reaches 0.1 mA at the rotation speed of 60 rpm. In this case, the H2 evolution process only occurs with sunlight irradiation. When the rotation speed is over 130 rpm, the peak photocurrent and peak dark current have nearly equal value. Direct electrolysis of water is almost simultaneous with photoelectrocatalysis of water. It is worth noting that the hydrogen production rate increases to 5.45 and 7.27 μL min−1 without or with light illumination at 160 rpm. The corresponding energy conversion efficiency is calculated to be 2.43% and 2.59%, respectively. All the results demonstrate such a self-powered system can successfully achieve the PEC hydrogen generation, exhibiting promising possibility of energy conversion. [ABSTRACT FROM AUTHOR]

Glass-ceramics were synthesized through the sol-gel method. The Thermogravimetry & Differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), BET, Scanning electron microscope (SEM), bioactivity and turbidometric tests were used to characterize the properties of the glass-ceramics. The TG-DSC results showed that the nitrates could be decomposed completely when the bioactive glass xerogel precursor was heat treated at 750°C. The synthesized glass-ceramic powders had an average particle size of about 3 μm to 20 μm with nanopores on the surface. The XRD results showed that the Na2Ca3Si6O16 and CaSiO3 were the major phases of the glass-ceramics heat treated at 600°C and 700°C, respectively. The flexural strength significantly increased from 79.2 MPa to 163.6 MPa with the sintering temperature increasing from 550°C to 600°C. The formation of carbonated hydroxyapatite can be proved by FT-IR results in this study. The synthesized glass-ceramics have good bioactivity and anti-bacterial property. [ABSTRACT FROM AUTHOR]

Abstract Monoclinic BiVO 4 (m-BiVO 4) thin films were deposited on the ZnO nanorod arrays (NRAs) for constructing a core/shell composite photoanode, leading to a significantly enhanced photoelectrochemical (PEC) performance. Specifically, the ZnO/BiVO 4 NRA sample displayed a photocurrent density of 2.3 mA/cm2 at 0.6 V vs. RHE under a visible light irradiation (100 mA/cm2), while the value was just 0.9 mA/cm2 for a ZnO NRA and 0.8 mA/cm2 for a BiVO 4 film. The enhanced PEC activity was mainly attributed to the role of ZnO nanorods as a rapid electron transport pathway, which could be also versified by the electrochemical impedance analysis (including the Nyquist and Mott-Schottky plots). Furthermore, a PEC biosensor was fabricated by using a ZnO/BiVO 4 NRA photoanode, leading to an acceptable sensitivity of 450 mA·cm−2·M−1 and a detection limit of 0.11 μM, respectively. [ABSTRACT FROM AUTHOR]

Abstract Monte Carlo simulations were employed to study the argon adsorption on kaolinite surface with an experimental comparison. By (001) surface simulation, the low energy peak of isotherm derivative was clearly assigned to the hydroxyl surface, and the high energy peak to the basal oxygen surface. The monolayer adsorption mechanism and the adsorption sites were made according to the distribution and potential of argon on both (001) surface. By simulations of (100) and (010) lateral surfaces, and complete outer surface, the difference between (001) surface simulation and experimental results was clarified and a new destination for derivative peaks was proposed. Graphical abstract Unlabelled Image Highlights • Derivative peaks of Ar adsorption isotherm for two (001) basal surfaces were clearly distinguished. • Monolayer adsorption mechanism of argon on kaolinite (001) surface • New destination of derivative peaks for experimental adsorption isotherm [ABSTRACT FROM AUTHOR]

Abstract Antibacterial porcelain layers were synthesized on Ti by laser-fusion method. The specimens were studied by XRD, FE-SEM, EDS, scratching test and anti-bacterial tests. The main crystalline phases of the antibacterial coatings are TiO 2 and CaTiO 3 , which are mainly caused by the metallurgical chemical reaction between the coating and the Ti-substrate during the process of the laser fusion. Due to the high temperature gradient perpendicular to the laser scanning direction, a coating with dendrites structure was formed on Ti. More dendrites are formed when the Ti content was increased, resulting in the greater roughness of the coating surface. The scratching bonding strength between the coating and Ti substrate reaches the maximum value (93.63 MPa) at Ti content of 20 wt%, which are much higher than the regular bonding strength between the common fused porcelain and Ti (only about 35–40 MPa). After cultivation for 10 h, the nano-silver particles embedded in antibacterial coating began to take on the role of the sterilization, and the higher the silver content was, the better the anti-bacterial properties of the coatings were. However, the Ti content did not significantly affect the anti-bacterial properties of the coatings at the same Ag content of 2 wt%. A granular hydroxyapatite layer was deposited on the antibacterial coating's surface after immersion in simulated body fluid, which demonstrated good bioactivity of the coatings. Highlights • Laser fusion was used to form an antibacterial porcelain layers on Ti. • The bonding strength of the coating is much higher than that of common fused. • The Ti content did not affect the coating's anti-bacterial properties. • A granular HA layer was deposited on the antibacterial coating's surface. [ABSTRACT FROM AUTHOR]

Abstract The titanium surface was laser-nitrided to form a TiN intermediate layer and then a bonding porcelain layer was laser fused on it. The specimens were studied by XRD, FE-SEM and EDS tests. A porous titanium nitride layer about 20 μm was synthesized on Ti surface, and the main phases of which were c-TiN and TiN 0.3. The Vickers hardness of the TiN layer was 618.68 HV, which is about 3 times of the titanium (202.9 HV). The EDS results showed the TiN layer prepared at 300W was a non-stoichiometri compound with mole ratio of Ti to N about 1:0.621. The porcelain coating laser fused on the TiN layer inherited the columnar structure of TiN, which had a rhombus-like intersecting surface. The highest scratching bonding strength (193.21 ± 23.33 MPa) between TiN layer and Ti was obtained at nitriding power of 300W. The porcelain coating laser fused on the TiN layer inherited the columnar structure of TiN, which had a rhombus-like intersecting surface. The bonding strength between coating and titanium (67.28 MPa) were much higher than the regular bonding strength between the porcelain and Ti (only about 35–40 MPa), which could be ascribed to the good chemical reactivity and wettability between the TiN layer and porcelain. Highlights • A non-stoichiometri TiN layer was prepared on Ti by laser nitriding. • The laser nitriding improved the wettability between the porcelain and Ti. • Good chemical reactivity and wettability enable the good bonding strength. [ABSTRACT FROM AUTHOR]

kaolinite nanotubes (KNTs) were firstly used to coload TiO 2 nanoparticles and carbon nitride (C 3 N 4 ) nanosheets for photocatalytic degradation of methylene blue (MB) dye. The influence of C 3 N 4 amount on the photocatalytic activity of composites was evaluated. The optimum sample showed an ultrahigh efficiency/effective mass ratio that is 18.8 and 24.7 times higher than these of pure TiO 2 and C 3 N 4 references, respectively. The enhancement of photocatalytic performance for clay-semiconductor composites can be attributed to the Z-scheme transport of photoproduced electrons and the good dispersion of catalyst particles on KNTs. The work provides an example that KNTs can be used as a promising support with very little catalysts but high photocatalytic performance. [ABSTRACT FROM AUTHOR]

Si photoelectrodes with two different morphology, including the porous Si (PSi) and Si nanowires (SiNWs), have been prepared via a facile wet-chemical etching method. The SiNW displays acceptable stability and photocurrent density (J) of 1.1 mA∙cm −2 at 1.23 V versus ( vs. ) reversible hydrogen electrode (RHE) under solar irradiation, which are superior to the PSi and attributed to the improved surface area and light harvesting capability. Electrochemical impedance technique is employed to analyze the mechanism underlying the differences in PEC performance. A prototype PEC bio-sensor is fabricated using a SiNW electrode for detection of glutathione (GSH), leading to acceptable detect limit of 0.81 μmol L −1 (μM) and sensitivity of 61.32 mA cm −2  M −1 . Further, it is found that both the PEC stability and photoresponse of SiNW electrodes could be enhanced efficiently by depositing thin Mo layers. Our studies demonstrated the prospect of Si as an electrode material for applying in the PEC or bio-sensing fields. [ABSTRACT FROM AUTHOR]

ZnO nanowire arrays (NWAs) were prepared on transparent conducting fluorine doped tin oxide (FTO) substrates through a facile hydrothermal method, followed by a 500 °C annealing to improve their crystalline qualities and photoelectrochemical (PEC) activities. It was found that the annealing didn't change the morphology, but resulted in a significant reduction of the donor concentration. Temperature-dependent photoluminescence (PL) was carried out for a comprehensive analysis of the effect from annealing. Noteworthy, four dominant peaks were identified from the 10 K spectrum of a 500 °C annealed sample, and they were assigned to FX, D 0 X, (e, D 0 ) and (e, D 0 ) -1LO, respectively. Of them, the FX emission was only existed below 130 K, while the room-temperature (RT) PL spectrum was dominated by the D 0 X emission. [ABSTRACT FROM AUTHOR]

Low-temperature-processed perovskite solar cells (PSCs), which can be fabricated on rigid or flexible substrates, are attracting increasing attention because they have a wide range of potential applications. In this study, the stability of reduced graphene oxide and the ability of a poly(triarylamine) underlayer to improve the quality of overlying perovskite films to construct hole-transport bilayer by means of a low-temperature method are taken advantage of. The bilayer is used in both flexible and rigid inverted planar PSCs with the following configuration: substrate/indium tin oxide/reduced graphene oxide/polytriarylamine/CH3NH3PbI3/PCBM/bathocuproine/Ag (PCBM = [6,6]-phenyl-C61-butyric acid methyl ester). The flexible and rigid PSCs show power conversion efficiencies of 15.7 and 17.2%, respectively, for the aperture area of 1.02 cm2. Moreover, the PSC based the bilayer shows outstanding light-soaking stability, retaining ≈90% of its original efficiency after continuous illumination for 500 h at 100 mW cm−2. [ABSTRACT FROM AUTHOR]

Bonding porcelain layer was fused on Ti surface by laser cladding process using a 400 W pulse CO 2 laser. The specimens were studied by field-emission scanning electron microscopy, X-ray diffraction and bonding tests. During the laser fusion process, the porcelain powders were heated by laser energy and melted on Ti to form a chemical bond with the substrate. When the laser scanning speed decreased, the sintering temperature and the extent of the oxidation of Ti surface increased accordingly. When the laser scanning speed is 12.5 mm/s, the bonding porcelain layers were still incomplete sintered and there were some micro-cracks in the porcelain. When the laser scanning speed decreased to 7.5 mm/s, vitrified bonding porcelain layers with few pores were synthesized on Ti. [ABSTRACT FROM AUTHOR]

A new approach was developed to adjust N doping amount in anatase single crystals with well-faceted shape and micron size, using a novel liquid dopant from the chemical recycling of the wasted supernatant solution in our previous experiments. The dependence of microstructure and property evolution on N doping amount was investigated systematically. The results show that all prepared N-doped samples are pure anatase with the morphology of truncated octahedral bipyramid including both {001} and {110} reactive facets. With the increase of N doping, the single crystals become angular and the thickness decreases, the aggregation of crystals increases, the photo-absorption capacity in visible region is enhanced and the absorption band edge is gradually red-shifted. The photocatalytic efficiency of the samples for the degradation of methylene blue (MB) or phenol under visible light irradiation gradually increases, but when the volume of dopant increases to 2 ml, the photoactivity of TiO 2 decreases. The optimal volume of N dopant is 1 ml and A(6:1) shows the highest photodegradation rate. The effective N doping of wasted supernatant is mainly due to the previously formation of Ti-N linkage, and hence a N doping mechanism is proposed. This work provides a new opportunity for in-situ modification of anatase single crystals with well-faceted shape and micron size, and hence, a basis for development of some advanced materials, for example porous single crystals. [ABSTRACT FROM AUTHOR]

Bioglass coatings derived from electrophoretic deposition method were fused on Ti surface by laser cladding process using a continuous CO 2 laser. The specimens were studied by field-emission scanning electron microscopy, X-ray diffraction and bonding tests. Titanium oxide layer with hierarchical structures consisting of submicron rows of leaf-like embossments and nano-pores was obtained by combining acid etching and anodization processes, which increased the surface roughness of Ti. When heat-treatment temperature was 700 °C and high, CaSiO 3 phase began to crystallize from the bioglass matrix and the crystallinity reached its maximum at 700 °C. During the electrophoretic deposition process, porous bioglass coatings composed of bioglass particles and fibers were deposited on Ti surface. Bioglass coatings with similar hierarchical structure containing submillimeter bioglass beads and microfibers were synthesized on Ti surface by laser fusion. There are no obvious microcracks at the interface of the Ti-coating, which revealed the good bonding between Ti-porcelain. With the laser scanning distance decreased, the bond strength increased accordingly. After only one day immersion in SBF, calcium phosphate began to precipitate on the bioglass coatings' surfaces. The thickness of the calcium phosphate precipitation and the amount of microparticles increased with immersion time. [ABSTRACT FROM AUTHOR]

Niobium oxyfluoride (Nb 3 O 7 F) nanomaterials have been the focus of photocatalysis due to their excellent optoelectronic properties. However, the practical application of Nb 3 O 7 F suffers from the low photocatalytic efficiency and quantum efficiency due to their wide bandgap. In this paper, Nb 2 O 5 -modified Nb 3 O 7 F hybrid photocatalysts are crafted in situ through directly thermal decomposition method for the first time. The crystallographic phase sensitively correlates with heat-treated temperature, posing great challenges to synthesize active products with tuned phases, composition and properties. The photocatalytic activities have been investigated by degrading methylene blue (MB) under visible light irradiation. Compared with pure Nb 3 O 7 F, Nb 3 O 7 F/Nb 2 O 5 nanocomposites exhibit enhanced photocatalytic performance due to perfect crystallization and synergistic effect. Nb 3 O 7 F-500 catalysts with 0.391 min −1 rate constant can achieve final 96.7% degradation rate in 60 min, while pure Nb 3 O 7 F catalysts with 0.376 min −1 rate constant only get 49.3% in the same time. The cycle experiments show Nb 3 O 7 F/Nb 2 O 5 photocatalysts have good stability. Such hybrid nanocomposites are very attractive for photocatalytic applications. [ABSTRACT FROM AUTHOR]

Development of novel hybrid semiconductor photocatalysts has been of great concern for environmental, material and energy scientists in recent years. Herein, we develop a facile two-step sol-hydrothermal technique for preparation of Nb 3 O 7 F/MoS 2 nanocomposites for the first time. The photocatalytic performance was evaluated by monitoring the degradation of methyl blue (MB) dye under visible-light irradiation. Compared to pure Nb 3 O 7 F, Nb 3 O 7 F/MoS 2 nanocomposites exhibit higher photocatalytic efficiency and faster photocatalytic degradation rate. The remarkable enhancement of photocatalytic activity is attributed to the desirable multichannel-improved carrier dynamics, such as better visible-light absorption, more exposed active sites, promoted carrier separation and faster carrier transfer. This work sheds new light on the design and construction of novel high-performance photocatalysts. [ABSTRACT FROM AUTHOR]

NiO x have been considered as an excellent material for hole transport layer (HTL) of perovskite solar cells because of its wide band gap, excellent optical transmittance, proper chemical stability and energy level matching with perovskite materials. However, the power conversion efficiency (PCE) of inverted perovskite solar cells (PSCs) is hindered by the low conductivity of unmodified NiO x. Here, we reported an operative Na 2 S treated NiO x HTL, which could optimize the conductivity of the NiO x layers and the crystallinity of perovskite. The synergistic effect of Na cations and S anions could strengthen the conductivity of the NiO x HTL, improve the interface contact between NiO x and perovskite, and enhance the quality of the perovskite film, so as to boost photoelectricity performance of the device. The carrier dynamics have shown that doping of Na 2 S could not only diminish the interface defects of the HTL/perovskite layer, but also improve the hole extraction at the NiO x /perovskite interface. All these factors led to the improvements in short-circuit density (J sc), fill factor (FF) and PCE of inverted planar perovskite solar cells. Consequently, Na2S-decorated NiOx HTL contributes to a stable device which attains a champion efficiency of 16.9%. [ABSTRACT FROM AUTHOR]

Surface modifications of Ti and nano-composite coatings were employed to simultaneously improve the surface roughness, corrosion resistance and chemical bonding between porclain-Ti. The specimens were studied by field-emission scanning electron microscopy, surface roughness, differential scanning calorimetry, Fourier transform infrared spectroscopy, corrosion resistance and bonding strength tests. The SEM results showed that hybrid structures with micro-stripes, nano-pores and nano-protuberances were prepared by surface modification of Ti, which significantly enhanced the surface roughness and corrosion resistance of Ti. Porous nano-composite coatings were synthesized on Ti anodized with pre-treatment in 40% HF acid. TiO 2 nanoparticles were added into the hybrid coating to increase the solid phase content of the sols and avoid the formation of microcracks. With the TiO 2 content increasing from 45 wt% to 60 wt%, the quantities of the microcracks on the coating surface gradually decreased. The optimal TiO 2 content for the nanocomposite coatings is 60 wt% in this research. Compared to the uncoated group, the bonding strength of the coated groups showed a bonding strength improvement of 23.96%. The cytotoxicity of the 4# coating group was ranked as zero, which corresponds to non-cytotoxicity. [ABSTRACT FROM AUTHOR]

TiO 2 films of different thickness were prepared with the additives of acetylacetone (ACAC) and diethanolamine (DEA), respectively. The results showed that not only the additives but also the film thickness affected the optical properties, surface roughness, absorption and laser-induced damage threshold (LIDT) of TiO 2 films. The LIDT of the film with DEA was higher than that with ACAC, which was attributed to the lower defect density. With the film thickness increase, the significant decrease in LIDT of the film with ACAC was mainly due to the reduced band gap. It indicated that the amount of ACAC or the film thickness should be reduced as much as possible for preparing high LIDT TiO 2 films. After laser damage, the films with ACAC showed cracks, whereas the films with DEA showed spalling. The difference between the damage morphologies was discussed in details. [ABSTRACT FROM AUTHOR]

Silver containing hybrid coatings were synthesized on titanium by sol–gel process. The specimens were studied by transmission electron microscopy, field-emission scanning electron microscopy, bonding test and bacterial counting method. The solid phase content of the sols was increased by the addition of TiO 2 nanoparticles, which avoided the formation of microcracks on the coatings surface. The bonding strength of the coated groups showed a bonding strength improvement of 10.6% compared to the uncoated group. The percent reduction in bacterial count against Staphylococcus aureus seeded on silver containing hybrid coating surface was approximately 99.3% after 24 h incubation, which indicated the strong antibacterial activity of the coating. [ABSTRACT FROM AUTHOR]

In this study, three film samples (ZnO, ZnS and ZnO/ZnS heterojunction) were prepared by a facile magnet sputtering deposition method. All the films exhibited the good crystal quality and smooth surface. Further, the X-ray photoelectron spectroscopy (XPS) was employed to examine the band offset between ZnO and ZnS layers at the interface. It was demonstrated that the ZnO/ZnS bilayers exhibited a II-type band alignment with a valence-band (VB) offset of 1.04 eV, which was accordance with the calculation results. It thus suggested that such a heterostructure was suitable for application as a photocatalyst or photoanode for water splitting or photoelectric conversion. [ABSTRACT FROM AUTHOR]

In this paper, anatase porous single crystals (PSCs) with different pore sizes were hydrothermally synthesized by using silica spheres as template. The products exhibit uniform porous structure which is consistent with silica template dimensions. Sharp Laue diffraction patterns, uniform lattice frings in different regions and occurrence of partial porous single crystal unequivocally prove monocrystalline nature of the samples. All PSC samples display high degree of crystallinity. Specific surface area increases with decrease of pore size and adsorption–desorption isotherms of type IV further confirm porous structure of PSCs. All samples show the strong absorption of ultraviolet light, the extent of which increases with decrease of pore size. Photoluminescence intensity decreases as pore size decreases, however, the intensity for S1 sample with minimum pore size is somewhat higher than that of S2. Photocatalytivity tests show the similar results which may be attributed to the combined effect of the surface active sites, the exchange between species in holes and those outside of PSCs, and electron mobility in framework. Moreover, the “seeding template-crystallization” mechanism for PSCs formation was discussed in detail. Based on these results, PSCs anatase with different purposes can be achieved by means of precise adjust for pore dimension and surface area. [ABSTRACT FROM AUTHOR]

Ag 3 PO 4 microparticles (MPs) were annealed in air at various temperatures (100–500 °C) and time (30–120 min). It is surprising that both the phase structure and photocatalytic (PC) activities didn’t descend even if the powders samples were annealed at 400 °C for 30 min, which made it possible to obtain Ag 3 PO 4 films similar to the common semiconductor photocatalysts, such as TiO 2 . However, the particle sizes of MPs were observed to get increased significantly, resulting in a lowering of the specific surface area and a change of color. By excluding a few common causes, the excellent PC activities of the sintered samples are speculated to the improved crystallized quality, which also makes it possible to construct the photoelectrodes based on Ag 3 PO 4 films for water splitting or photoelectric conversion. [ABSTRACT FROM AUTHOR]

Porous electrode materials with large specifi c surface area, relatively short diffusion path, and higher electrical conductivity, which display both better rate capabilities and good cycle lives, have huge benefi ts for practical applications in lithium-ion batteries. Here, uniform porous NiCo2O4 nanorods (PNNs) with pore-size distribution in the range of 10-30 nm and lengths of up to several micrometers are synthesized through a convenient oxalate co-precipitation method followed by a calcining process. The PNN electrode exhibits high reversible capacity and outstanding cycling stability (after 150 cycles still maintain about 650 mA h g-1 at a current density of 100 mA g-1 ), as well as high Coulombic effi ciency (>98%). Moreover, the PNNs also exhibit an excellent rate performance, and deliver a stable reversible specifi c capacity of 450 mA h g-1 even at 2000 mA g-1 . These results demonstrate that the PNNs are promising anode materials for high-performance Li-ion batteries. [ABSTRACT FROM AUTHOR]

In this study, Ta 2 O 5 sol was synthesized from TaCl 5 precursor, and its time dependence of the viscosity, particle size distribution and photoluminescence spectra were studied. Then, Ta 2 O 5 films were prepared using this sol and were succeeding annealed at different temperatures without carbonization and cracks. It was found that the films had good properties such as high transparency, small absorption and high laser-induced damage threshold (LIDT). The LIDT decreased with the increase of the annealing temperature probably due to the acetylacetone in the films. The laser-induced damage morphologies of the films after annealing were different. With the annealing temperature increase, the dominant factor of the laser-induced damage transformed gradually from the stress to the thermal. According to the LIDT and damage morphologies, a structure evolution model of the films annealed at different temperatures was proposed. [ABSTRACT FROM AUTHOR]

Ta 2 O 5 films deposited by ion beam sputtering were post-treated with different methods. The optical properties, microstructures, surface morphologies, absorption and laser-induced damage threshold (LIDT) at 1064 nm and 12 ns of the films were comparatively studied. Annealing conduced to larger changes of optical transmittance and surface morphologies whereas it led to smaller changes of absorption and LIDT than laser conditioning. As it was shown, all the three post-treatment methods in this study were beneficial to the laser damage resistance of the films, yet the details of the defect elimination caused by these methods were different. A defect evolution model was proposed, which revealed the different effects of post-treatment methods on the defect repair of the films. The highest LIDT achieved by the combination of annealing and laser conditioning was due to their complementary effect which resulted in the lowest defect density and the smallest defect size of the film. [ABSTRACT FROM AUTHOR]

Highlights: [•] High LIDT Ta2O5 films were prepared using TaCl5 as precursor. [•] We revealed the functions of H2O2 in the sol formation. [•] The high LIDT was attributed to the nearly free of defects. [Copyright &y& Elsevier]

Highlights: [•] Effects of oxygen deficiency on the laser damage are investigated. [•] In this research we combine experimental methods and first principles calculations. [•] The damage resistance of different oxide films with oxygen vacancy is revealed. [Copyright &y& Elsevier]

Catalysts with high activity and stability for methanol electrooxidation are crucial for the commercialization of direct methanol fuel cells. In this work, the performance of nanocrystal tungsten nitride hybrid (WN/C) supported Pt catalyst for methanol electrooxidation is reported. X-ray diffraction (XRD) measurements and transmission electron microscopy (TEM) are adopted to investigate the physicochemical properties of WN/C and the prepared catalysts. Cyclic voltammetry, chronopotentiometry and chronoamperometry measurements are employed to study the electrocatalytic properties of the prepared catalysts. The tungsten nitride supported Pt (Pt-WN/C) catalysts exhibit significantly improved performance towards methanol electrooxidation in acidic aqueous solutions in comparison with other catalysts. The reason could predominantly originate from the synergistic effect between WN and Pt in the Pt-WN/C catalysts and the nitrogen-doping effects of the carbon supports, which could be a promising anode catalyst for direct methanol fuel cells. [ABSTRACT FROM AUTHOR]

Highlights: [•] The as-obtained AgBr/Ag3PO4 hybrid structures exhibited enhanced photocatalytic activity and recyclability than pure Ag3PO4 and AgBr. [•] The 50%AgBr/Ag3PO4 hybrid was completely photodegradation RhB solution in 7min and still maintained high activity after four successive cycles of degradation. [•] The mechanism that the enhanced properties of hybrids were attributed to more high active sites and suitable band energy structure was proposed. [Copyright &y& Elsevier]

Highlights: [•] We report a simple hydrothermal approach to prepare TiO2/TiB2 nanowall. [•] TiO2/TiB2 nanowall has better decolorization rate than commercial A-TiO2. [•] UV–vis spectra show that absorption peak and absorption edge for TiO2/TiB2 nanowall shift to a lower energy. [•] XPS and EDX indicate that the shift of absorption peak and absorption edge may result from N-doping in A-TiO2. [Copyright &y& Elsevier]

Abstract: Zn0.85Sb0.1O films were synthesized by pulsed laser deposition (PLD). The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) measurements were carried out to evaluate the microstructure of the films. These films exhibited a single-phase hexagonal structure with (002) preferred orientation, despite the high Sb content of ∼10% and the resulting large lattice distortion in the films. Moreover, the films showed semiconductor properties with high resistivity of ∼104 Ωcm, which was possibly related to a compensation of intrinsic defects. Compared with the undoped ZnO, a reduction in the band gap by 40meV was clearly observed in ultraviolet–visible absorption spectra. [Copyright &y& Elsevier]

Abstract: Combustion synthesis was adopted to successfully synthesize molybdenum–silicon–chromium (Mo−Si−Cr) alloys by the mode of self-propagating high-temperature synthesis (SHS). The experimental study of combustion synthesis of Mo−Si−Cr alloys was conducted on elemental powder compacts. Powder compacts with nominal compositions including MoSi2, (Mo0.95Cr0.05)Si2, (Mo0.90Cr0.10)Si2, (Mo0.85Cr0.15)Si2, (Mo0.80Cr0.20)Si2, (Mo0.75Cr0.25)Si2 and (Mo0.70Cr0.30)Si2 were employed in combustion synthesis experiments. The combustion mode, combustion temperature, flame-front propagation velocity and product structure were investigated. The results showed that Mo−Si−Cr alloys were synthesized by an unsteady state combustion mode with a spiral-trajectory reaction front. The peak combustion temperature reduced with the addition of Cr to Mo–Si system. The flame-front propagation velocity decreased with an increase in Cr content of the powder compact. The X-ray diffraction (XRD) results showed that the crystal structure of the combustion product changed from Cllb-type structure (Mo0.90Cr0.10)Si2 to C40-type structure (Mo0.85Cr0.15)Si2 with increase in Cr content of Mo–Cr–Si alloys. The intensities of diffraction peaks of the C40-type phase gradually increased with increase in Cr content. [Copyright &y& Elsevier]

Abstract: In this work an efficient functionalizing method of carbon nanotubes (CNTs) by intermittent microwave heating (IMH) KOH media is reported. The performance of such modified CNTs as Pt electrocatalysts supports is demonstrated. FTIR spectrum and Raman spectrum are used to investigate the surface state of the CNTs. TEM technology is employed to study the dispersion of Pt particles for the prepared electrocatalysts. Meanwhile, cyclic voltammetry and chronopotentiometry measurements are adopted to investigate the corresponding activity and stability of the electrocatalysts. The results indicate that the CNTs functionalized by the IMH method in the form of 15s-ON/10s-OFF for pulse 20 repetitions used as electrocatalysts supports shows significantly higher activity and stability towards methanol electrooxidation in comparison with the CNTs decorated in other forms in the present study. The present method is simple and economic and displays a probability of mass production for supporting materials and electrocatalysts as well. [Copyright &y& Elsevier]

Abstract: The effect of the addition of diluent to Mo–Si system on the formation of MoSi2 by mechanically-induced self-propagating reaction was investigated in a high-energy ball mill. MoSi2 intermetallic was added as diluent to Mo–Si powder mixture. The structure and morphology of the reaction product was analyzed by X-ray diffraction and scanning electron microscope. The diluent decreased the adiabatic temperature, increased the ignition temperature and modified the Mo/Si reactants interface. Therefore, the incubation period of mechanically-induced self-propagating reaction was extended from 90min to 140min with the addition of diluent from 0wt% to 10wt% to Mo–Si powder mixture. The extended milling time reduced the size of agglomerated particles and fine MoSi2 product was obtained. [Copyright &y& Elsevier]

Abstract: The combustion synthesis behavior of Mo–Si–B powder was investigated. Test specimens with nominal compositions including MoSi2, Mo(Si0.975B0.025)2, Mo(Si0.95B0.05)2, Mo(Si0.925B0.075)2 and Mo(Si0.9B0.1)2 were employed. The combustion mode, propagation velocity of combustion wave, combustion temperature and combustion product structure were studied. The results showed that the combustion wave propagated along a spiral trajectory till reaching the bottom of the compacts. The combustion temperature was increased by the addition of boron, to as high as 1922K in the case of the Mo(Si0.95B0.05)2 sample. However, the flame-front propagation velocity decreased as a result of the addition of boron. The X-ray diffraction results showed that the combustion products of the Mo(Si0.975B0.025)2 and Mo(Si0.9B0.1)2 samples were composed of MoSi2 with minor MoB. Those of the Mo(Si0.95B0.05)2 and Mo(Si0.925B0.075)2 samples were composed of MoSi2 with minor MoB and MoB2. And traces of Mo2B5 were identified in the Mo(Si0.95B0.05)2 sample. [Copyright &y& Elsevier]

Abstract: The effects of tungsten and aluminum additions to Mo–Si system on the formation of MoSi2 by mechanically-induced self-propagating reaction in a high-energy ball mill were investigated by X-ray diffraction. The incubation time for mechanically-induced self-propagating reaction to form MoSi2 was 90min in Mo–Si system. With the addition of tungsten to Mo–Si system, the incubation time of mechanically-induced self-propagating reaction of (W x ,Mo1−x )Si2 system was prolonged. It was due to the decrease of adiabatic temperature with increase in x, and the mechanically-induced self-propagating reaction was not observed until 150min of high-energy milling in (W x ,Mo1−x )Si2 powder sample with x equals to 0.4. Conversely, the minor aluminum (y <0.2 in Mo(Si1−y ,Al y )2 system) substituting for silicon had shorten the incubation period and accelerated the reaction. When tungsten and aluminium were added simultaneously to Mo–Si system, the mechanically-induced self-propagating reaction was observed in (W0.1,Mo0.9)(Si0.9,Al0.1)2 sample, but it was not observed in (W0.2,Mo0.8)(Si0.8,Al0.2)2 and (W0.3,Mo0.7)(Si0.7,Al0.3)2 samples. [Copyright &y& Elsevier]