Biofunctionalization of porous titanium coatings through sol–gel impregnation with a bioactive glass–ceramic

In implant technology, open porous Ti coatings are applied as functional surface layers on prosthetic devices to improve osseointegration. Since a successful clinical performance strongly depends on the (initial) quality of bone ingrowth in the porous structure, surface functionalization of the porous Ti to incorporate an additional osteoconductive capacity is recommended. In this paper, a bioactive glass–ceramic coating is applied into the open porous network of Ti coatings with a pore throat size of 1–20 μm through a sol–gel process. Using an all-alkoxide precursor route, homogeneous amorphous powders of three- (SiO₂–CaO–P₂O₅) and four-component (SiO₂–CaO–Na₂O–P₂O₅) bioactive glass compositions are prepared. By sol impregnation followed by a heat treatment, it is possible to deposit a micrometer thin bioactive glass–ceramic layer on the walls of the internal pore surface, while the original porosity and the open pore structure of the Ti coatings are maintained. The tensile adhesion strength of the Ti/bioactive glass–ceramic composite coatings is 22 to 29 MPa, suggesting a good mechanical adhesion.     

Resistivity studies on Ga2Te3 and In2Te3 under high pressures

The resistivities of III–VI semiconductors Ga₂Te₃ and In₂Te₃ were found to decrease abruptly under hydrostatic pressures between 1 and 7 GPa. The transition was reversible for Ga₂Te₃ but irreversible in the case of In₂Te₃ due to decomposition. These results are compared with the behaviour of II–VI and III–V semiconductors and transition pressures correlated with lattice constants.     

Enhanced Chemisorption and Catalytic Effects toward Polysulfides by Modulating Hollow Nanoarchitectures for Long‐Life Lithium–Sulfur Batteries

Hollow nanostructures with intricate interior and catalytic effects hold great promise for the construction of advanced lithium–sulfur batteries. Herein, a double‐shelled hollow polyhedron with inlaid cobalt nanoparticles encapsulated by nitrogen‐doped carbon (Co/NC) nanodots (Co‐NC@Co₉S₈/NPC) is reported, which is acquired by using imidazolium‐based ionic‐polymer‐encapsulated zeolitic imidazolate framework‐67 as a core‐shelled precursor. The Co/NC nanodots promote redox kinetics and chemical adsorbability toward polysulfides, while the interconnected double shells serve as a nanoscale electrochemical reaction chamber, which effectively suppresses the polysulfide shuttling and accelerates ion/electron transport. Benefiting from structural engineering and reaction kinetics modulation, the Co‐NC@Co₉S₈/NPC‐S electrode exhibits high cycling stability with a low capacity decay of 0.011% per cycle within 2000 cycles at 2 C. The electrode still shows high rate performance and cyclability over 500 cycles even in the case of high sulfur loading of 4.5 mg cm^?2 and 75 wt% sulfur content. This work provides one type of new hollow nanoarchitecture for the development of advanced Li–S batteries and other energy storage systems.     

Synthesis of molybdenum (IV) disulfide using a single-source method

Molybdenum(IV) disulfide was prepared by the thermalysis of the single molecule precursor [Mo₂O₄(S₂CNEt₂)₂] (Et: ethyl group). The thermalysis was monitored by thermogravimetric analysis and FT-infrared spectroscopy. The MoS₂ materials obtained during the thermalysis experiments were characterized in terms of their morphological and optical characteristics.     

Correlations between the thermodynamic properties of II–VI and III–VI phases

Simple correlation models are considered that can be used to predict unknown and refine questionable thermodynamic properties of II–VI and III–VI semiconductors. An empirical rule is proposed: for a particular combination of Periodic Groups, the enthalpy and Gibbs energy of formation of isostructural A _n B _m compounds are linear functions of the melting point.     

Ultrafine Co3O4 Nanoparticles within Nitrogen‐Doped Carbon Matrix Derived from Metal–Organic Complex for Boosting Lithium Storage and Oxygen Evolution Reaction

Transition metal oxides have recently received great attention for application in advanced lithium‐ion batteries (LIBs) and oxygen evolution reaction (OER). Herein, the ethylenediaminetetraacetic cobalt complex as a precursor to synthesize ultrafine Co₃O₄ nanoparticles encapsulated into a nitrogen‐doped carbon matrix (NC) composites is presented. The as‐prepared Co₃O₄/NC‐350 obtained by pyrolysis at 350 °C demonstrates superior rate performance (372 mAh g^?1 at 5.0 A g^?1) and high cycling stability (92% capacity retention after 300 cycles at 1.0 A g^?1) as anode for LIBs. When evaluated as an electrocatalyst for OER, the Co₃O₄/NC‐350 achieves an overpotential of 298 mV at a current density of 10 mA cm^?2. The NC‐encapsualted porous hierarchical structure assures fast and continuous electron transportation, high activity sites, and strong structural integrity. This works offers novel complex precursors for synthesizing transition metal–based electrodes for boosting electrochemical energy conversion and storage.     

Alternative approaches to fabrication of gold-modified TiO2 nanotubes

Three approaches, impregnation–reduction, deposition and direct assembly, are used to fabricate gold-modified TiO₂ nanotubes. Prepared materials are characterized with powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), UV–visible absorption spectroscopy and BET, etc. The gold-modified TiO₂ nanotubes prepared via various procedures exhibit distinct difference in structure. By impregnation–reduction approach, gold-modified TiO₂ nanotubes with large gold particles are fabricated. The gold particles are either deposited on or encapsulated in TiO₂ nanotubes. However, by using gold hydrophilic colloidal dispersion as gold precursor, gold particles in the modified TiO₂ nanotubes are very small. Gold particles only adhere to the outer surface of TiO₂ nanotubes after deposition process, whereas adhere to not only the outer but also the inner walls of TiO₂ nanotubes after direct assembly process. A possible mechanism is proposed to illustrate the formation of gold-modified nanotubes that are prepared by direct assembly process.     

General trends of deposit accumulation in porous hosts during cyclic impregnation with rare-earth and actinide waste solutions

A theoretical model is constructed to describe the dynamics of the increase in the weight of porous matrices upon introduction of rare-earth and actinide radioactive waste from solutions via repeated cycles of impregnation, drying, and high-temperature annealing. The modeling results for waste immobilization in porous Al₂O₃ and ZrO₂ agree well with experimental data.     

Superior Photocatalytic H2 Production with Cocatalytic Co/Ni Species Anchored on Sulfide Semiconductor

Downsizing transition metal‐based cocatalysts on semiconductors to promote photocatalytic efficiency is important for research and industrial applications. This study presents a novel and facile strategy for anchoring well‐dispersed metal species on CdS surface through controlled decarboxylation of the ethylenediaminetetraacetate (EDTA) ligand in the metal–EDTA (M–EDTA) complex and CdS mixture precursor to function as a cocatalyst in the photocatalytic H₂ evolution. Microstructure characterization and performance evaluation reveal that under visible light the resulting pentacoordinated Co(II) and hexacoordinated Ni(II) on CdS exhibits a high activity of 3.1 mmol h^?1 (with turnover frequency (TOF) of 626 h^?1 and apparent quantum efficiency (AQE) of 56.2% at 420 nm) and 4.3 mmol h^?1 (with TOF of 864 h^?1 and AQE of 67.5% at 420 nm), respectively, toward cocatalytic hydrogen evolution, and the cocatalytic activity of such a hexacoordinated Ni(II) even exceeds that of platinum. Further mechanistic study and theoretical modeling indicate that the fully utilized Co(II)/Ni(II) active sites, efficient charge transfer, and favorable kinetics guarantee the efficient activities. This work introduces a promising precursor, i.e., M–EDTA for planting well‐dispersed transition metal species on the sulfide supports by a facile wet‐chemistry approach, providing new opportunities for photocatalytic H₂ production at the atomic/molecular scale.     

CuSbS2 thin films by heating Sb2S3/Cu layers for PV applications

In this work, we present the preparation of CuSbS₂ thin films of approximately 850 nm in thickness by heating glass/Sb₂S₃/Cu layers in low vacuum and their application in PV structures: Glass/SnO₂:F/n-CdS/p-CuSbS₂/C/Ag. The Sb₂S₃ thin films were chemically deposited from a solution containing SbCl₃ and Na₂S₂O₃ at 40 °C on well cleaned substrates. Copper thin films of 50 nm were thermally evaporated on Sb₂S₃ films of thickness ~600 and 800 nm and the glass/Sb₂S₃/Cu precursor layers were heated in vacuum at 300 and 350 °C for 1 h. Structural, morphological, optical and electrical characterizations of the annealed thin films were analyzed by X-ray diffraction, Atomic force microscopy, UV–Vis spectrometry and photoresponse measurements. Studies on identification and chemical state of the elements were done using X-ray photoelectron spectroscopy. Photovoltaic devices were prepared using CuSbS₂ thin films as absorber and chemical bath deposited CdS thin films as window layer on FTO coated glass substrates. The photovoltaic parameters of the devices were evaluated from the corresponding J–V curves, yielding J_sc, V_oc and FF values in the range of 1.03–1.55 mA/cm², 250–294 mV and 0.46–0.57 respectively, performed using a solar simulator under illumination of AM1.5 radiation.     

Co9S8 Nanoparticles‐Embedded N/S‐Codoped Carbon Nanofibers Derived from Metal–Organic Framework‐Wrapped CdS Nanowires for Efficient Oxygen Evolution Reaction

Metal–organic frameworks (MOFs) with tunable compositions and morphologies are recognized as efficient self‐sacrificial templates to achieve function‐oriented nanostructured materials. Moreover, it is urgently needed to develop highly efficient noble metal‐free oxygen evolution reaction (OER) electrocatalysts to accelerate the development of overall water splitting green energy conversion systems. Herein, a facile and cost‐efficient strategy to synthesize Co₉S₈ nanoparticles‐embedded N/S‐codoped carbon nanofibers (Co₉S₈/NSCNFs) as highly active OER catalyst is developed. The hybrid precursor of core–shell ZIF‐wrapped CdS nanowires is first prepared and then leads to the formation of uniformly dispersed Co₉S₈/N, S‐codoped carbon nanocomposites through a one‐step calcination reaction. The optimal Co₉S₈/NSCNFs‐850 is demonstrated to possess excellent electrocatalytic performance for OER in 1.0 m KOH solution, affording a low overpotential of 302 mV to reach the current density of 10 mA cm^?2, a small Tafel slope of 54 mV dec^?1, and superior long‐term stability for 1000 cyclic voltammetry cycles. The favorable results raise a concept of exploring more MOF‐based nanohybrids as precursors to induce the synthesis of novel porous nanomaterials as non‐noble‐metal electrocatalysts for sustainable energy conversion.     

Palladium nanoparticles supported on amine-functionalized glass fiber mat for fixed-bed reactors on the effective removal of hexavalent chromium by catalytic reduction

Palladium nanoparticles were deposited on the amine-grafted glass fiber mat (GFM-NH₂) catalyst support by a conventional impregnation process followed by the borohydride reduction in aqueous solution at room temperature to create the designed Pd/GFM-NH₂ catalyst. By the use of large size glass fiber mat without nano/mesopores as the catalyst support, the internal mass transfer limitations due to the existence of nano/mesopores on the catalyst support were eliminated and the Pd/GFM-NH₂ catalyst could be easily separated from treated water due to the large size of the catalyst support. Batch experiments demonstrate its good catalytic reduction performance of Cr(VI) with formic acid as the reducing agent. It also demonstrated an efficient Cr(VI) removal and stability in a lab-prepared, packed fixed-bed tube reactor for the continuous treatment of Cr(VI)-containing water. Thus, it has a good potential for the catalytic reduction of Cr(VI) in the water treatment practice.     

The electric conductivity of nanodimensional cobalt oxide in a porous glass

Cobalt(II) oxide was introduced in an amount of 3.5–56.4 mass % into a porous glass by repeated cycles of impregnation with an aqueous solution of cobalt(II) nitrate followed by dehydration and thermal decomposition of the salt. The results of conductivity measurements, in combination with the data on the cobalt oxide volume and the specific area of the porous carrier, reflect the formation of sequential cobalt oxide monolayers on the surface of pore walls.     

High-performance nickel sulfide modified electrode material from single-source precursor for energy storage application

High-performance energy storage electrode materials are emerging demand in near future for the construction of supercapacitor with high energy and power densities. Herein, Nickel (II) Diethyldithiocarbamate was used as single-source precursor for Nickel Sulfide (Ni₉S₈) two-dimensional (2D) nanosheets (NSs) preparation and hexadecylamine as shape directing agent via simple solvothermal method. The orthorhombic structure of Ni₉S₈ NSs was confirmed by X-ray diffraction (XRD) pattern. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images revealed that as-prepared Ni₉S₈ nanoparticles possess sheet-like morphology. Besides, the thermal stability of Ni(DTC)₂ complex was studied by Thermogravimetric/Derivative Thermogravimetric (TG/DTG) with differential scanning calorimetric (DSC) analysis. The electrochemical properties of Ni₉S₈ NSs was studied using galvanostatic charge–discharge (GCD) and cyclic voltammetry (CV) techniques. From the charge–discharge study of Ni₉S₈ NSs, a high specific capacitance of 281 Fg^?1 was obtained at a current density of 1 Ag^?1 and up to 82% retentivity was achieved after 5000 cycles. Thus, the prepared Ni₉S₈ NSs could be the one of the attractive potential active electrode materials for the application of supercapacitor.

     

Facilitate Gas Transport through Metal‐Organic Polyhedra Constructed Porous Liquid Membrane

Type II porous liquids are demonstrated to be promise porous materials. However, the category of porous hosts is very limited. Here, a porous host metal–organic polyhedra (MOP‐18) is reported to construct type II porous liquids. MOP‐18 is dissolved into 15‐crown‐5 as an individual cage (5 nm). Both the molecular dynamics simulations and experimental gravimetric CO₂ solubility test indicate that the inner cavity of MOP‐18 in porous liquids is unoccupied by 15‐crown‐5 and is accessible to CO₂. Thus, the prepared porous liquids show enhanced gas solubility. Furthermore, the prepared porous liquid is encapsulated into graphene oxide (GO) nanoslits to form a GO‐supported porous liquid membrane (GO‐SPLM). Owing to the empty cavity of MOP‐18 unit cages in porous liquids that reduces the gas diffusion barrier, GO‐SPLM significantly enhances the permeability of gas.     

Core–Shell Tandem Catalysis Coupled with Interface Engineering For High-Performance Room-Temperature Na–S Batteries

The sluggish redox kinetics and shuttle effect seriously impede the large application of room-temperature sodium–sulfur (RT Na–S) batteries. Designing effective catalysts into cathode material is a promising approach to overcome the above issues. However, considering the multistep and multiphase transformations of sulfur redox process, it is impractical to achieve the effective catalysis of the entire S₈→Na₂S_x→Na₂S conversion through applying a single catalyst. Herein, this work fabricates a nitrogen-doped core–shell carbon nanosphere integrated with two different catalysts (ZnS-NC@Ni-N₄), where isolated Ni–N₄ sites and ZnS nanocrystals are distributed in the shell and core, respectively. ZnS nanocrystals ensure the rapid reduction of S₈ into Na₂S_x (4 < x ≤ 8), while Ni–N₄ sites realize the efficient conversion of Na₂S_x into Na₂S, bridged by the diffusion of Na₂S_x from the core to shell. Besides, Ni–N₄ sites on the shell can also induce an inorganic-rich cathode–electrolyte interface (CEI) on ZnS-NC@Ni-N₄ to further inhibit the shuttle effect. As a result, ZnS-NC@Ni-N₄/S cathode exhibits an excellent rate-performance (650 mAh g⁻¹ at 5 A g⁻¹) and ultralong cycling stability for 2000 cycles with a low capacity-decay rate of 0.011% per cycle. This work will guide the rational design of multicatalysts for high-performance RT Na–S batteries.     

Wurtzite-derived ternary I–III–O2 semiconductors

Abstract

Ternary zincblende-derived I–III–VI₂ chalcogenide and II–IV–V₂ pnictide semiconductors have been widely studied and some have been put to practical use. In contrast to the extensive research on these semiconductors, previous studies into ternary I–III–O₂ oxide semiconductors with a wurtzite-derived β-NaFeO₂ structure are limited. Wurtzite-derived β-LiGaO₂ and β-AgGaO₂ form alloys with ZnO and the band gap of ZnO can be controlled to include the visible and ultraviolet regions. β-CuGaO₂, which has a direct band gap of 1.47 eV, has been proposed for use as a light absorber in thin film solar cells. These ternary oxides may thus allow new applications for oxide semiconductors. However, information about wurtzite-derived ternary I–III–O₂ semiconductors is still limited. In this paper we review previous studies on β-LiGaO₂, β-AgGaO₂ and β-CuGaO₂ to determine guiding principles for the development of wurtzite-derived I–III–O₂ semiconductors.     

Infrared-to-visible conversion luminescence of Er3+ ions in lead borate transparent glass-ceramics

Transparent glass-ceramics were successfully prepared during controlled heat treatment of lead borate glasses. The PbF₂ particles were dispersed into a borate glass matrix which was evidenced by X-ray diffraction analysis. The phase identification revealed that crystalline peaks can be related to the orthorhombic PbF₂ phase. Green up-conversion luminescence due to the ⁴S_3/2–⁴I_15/2 transition of Er³⁺ ions was registered. In comparison to the precursor glass the luminescence intensity was considerably higher, whereas the luminescence linewidth slightly decreased in the studied oxyfluoride transparent glass-ceramics. It indicated that a part of the trivalent erbium was incorporated into the PbF₂ crystalline phase.     

Adhesion of glassy arsenic sulfide to quartz glass

Adhesion between As₂S₃ glass and quartz glass has been studied by a uniform pull-off method. The pull-off stress for the adhesion of glassy As₂S₃ to quartz glass has been determined as a function of temperature in the temperature range 110–190°C. The results demonstrate that, in the case of As₂S₃ glass, the adhesion strength increases exponentially with increasing test temperature and exceeds 2500 kPa at the glass transition temperature. We have studied how the adhesion strength is influenced by the contact temperature and time, tension test temperature, and quartz glass surface roughness.     

Preparation of II–VI and IV–VI semiconductor films for solar cells by the isovalent substitution technique with a CBD-made substrate

II–VI and IV–VI semiconductor films for solar cell applications, namely, CdTe, CdS, CdSe, PbS, PbSe and PbTe, can be prepared in a two-stage deposition process. In this work we illustrate the two-stage process to obtain PbTe and CdSe films from precursor oxide or hydroxide films deposited by chemical bath deposition (CBD). At the first stage, plumbonacrite Pb₁₀(CO₃)₆O(OH)₆ or cadmium oxide/hydroxide CdO₂/Cd(O₂)_0.88(OH)_0.24 films were deposited onto a glass substrate by CBD, using an ammonia-free low-temperature process in an alkaline aqueous solution with corresponding ion sources. Then, at the second stage, the obtained film was placed in a chemical vapor deposition (CVD) Hot Wall reactor with gas transportation, where it acted as a substrate in the reaction of isovalent substitution of Te or Se for the nonmetallic film component, thus forming PbTe and CdSe films. A nitrogen flux of 0.25 L/min was used as the transporting gas. The source temperature was adjusted between boiling (Tb) and melting point (Tm) to control the flux gas of the source. The substrate temperature was adjusted to improve film quality. Structural and optical investigation of the films proved their high quality, which determines the possibility of using them as solar cell elements, in particular, in multijunction cells.