Search

Corrosion behavior of AZ31 magnesium alloy in NH4+-bearing chloride solution with controlled pH was investigated by weight loss experiment, hydrogen collection, and electrochemical test combined with surface morphology and topography observation. The results show that NH4+ and pH of the solution can affect the corrosion of AZ31 magnesium alloy. The existence of NH4+ affects the formation and dissolution of corrosion products, which makes the protective effect of the corrosion product layer weaker. The change of pH value not only affects the corrosion mechanism of AZ31, but also alters the concentration of NH4+ ions in the solution, which further influences the corrosion product layer of AZ31, and finally makes the corrosion of AZ31 change significantly.

Aim: Felodipine (FDP), an antihypertensive drug possesses low water solubility and extensive first-pass metabolism leading to poor bioavailability. This impelled us to improve its solubility, bioavailability, and pharmacodynamic properties through the Nanocrystal (NC) approach. Methods: FDP-NC were prepared with Poloxamer F125 (PXM) by the antisolvent precipitation method. The experimental setup aimed at fine-tuning polymer concentration, the proportion of antisolvent to solvent, and the duration of ultrasonication for NC formulation. Results: Optimized formulation was characterized for particle size, solubility, and PDI. Particle reduction of 74.96 times was achieved with a 9X solubility enhancement as equated to pure FDP. The morphology of NC was found to be crystalline through scanning electron microscopy observation. The formation of the crystal lattice in FDP-NC was further substantiated by the XRD and DSC results. Lowering of the heat of fusion of FDP-NC is a clear indication of size reduction. The stability studies showed no substantial change in physical parameters of the FDP-NC as assessed by particle size, zeta potential, and drug content. Conclusion: The crystalline nature and improved solubility of FDP-NC improve the dissolution profile and pharmacodynamic data. The stability study data ensure that FDP-NC can be safely stored at 25°C. It is revealed that FDP-NC had a better release profile and improved pharmacodynamic effects as evident from better control over heart rate than FDP.

Background: Hydrophilic Hydroxypropyl Methylcellulose (HPMC) matrix tablets are the standard role model of the oral controlled-release formulation. Nevertheless, the HPMC kinetics for the mechanistic understanding of drug release and hydrodynamic behaviors are rarely investigated. This study aims to investigate the release behaviors of both HPMC and paracetamol (model drug) from the hydrophilic matrix tablet. Methods: Two different viscosity grades of HPMC were used (Low viscosity: 6 cps, High viscosity: 4,000 cps). Three different ratios of drug/HPMC (H:38.08%, M:22.85%, and L:15.23% (w/w) of HPMC amounts in total weight) matrix tablets were prepared by wet granulation technique. The release profiles of the drug and HPMC in a matrix tablet were quantitatively analyzed by HPLC and 1H-Nuclear Magnetic Resonance (NMR) spectroscopy. The hydrodynamic changes of HPMC were determined by the gravimetric behaviors such as swelling and erosion rates, gel layer thickness, front movement data,and distributive Near-Infrared (NIR) chemical imaging of HPMC in a matrix tablet during the dissolution process. Results: High viscosity HPMC tablets showed slower release of HPMC than the release rate of drug, suggesting that drug release preceded polymer release.Different hydration phenomenon was qualitatively identified and corresponded to the release profiles. The release behaviors of HPMC and drug in the tablet could be distinguished with the significant difference with fitted dissolution kinetics model (Low viscosity HPMC 6cps; Korsmeyer-Peppas model, High viscosity HPMC 4000cps; Hopfenberg model, Paracetamol; Weibull model) according to the weight of ingredients and types of HPMC. Conclusion: The determination of HPMC polymer release correlating with drug release, hydrodynamic behavior, and NIR chemical imaging of HPMC can provide new insights into the drug release- modulating mechanism in the hydrophilic matrix system.

Mineral replacement reactions are one of the most important phenomena controlling the geochemical cycle of elements on Earth. In the early years, solid-state diffusion was proposed as the main mechanism for mineral replacement reactions, but over the past 20 years the importance of the coupled dissolution-reprecipitation (CDR) mechanism has been recognized. In the presence of a fluid phase and at low temperatures (e.g.

Localized corrosion of metallic biomaterials is a concerning problem for implant applications. In the present work, the interaction between localized corrosion of Ti6Al4V implant material and adsorption of bovine serum albumin (BSA) was investigated by electrochemical tests, surface morphological and compositional analysis. The artificial crevice was set up on the Ti6Al4V surface to simulate the crevice corrosion of metallic implants. The results show that the BSA adsorption is regulated by the heterogeneous metallic ion release resulted from the crevice corrosion. The negatively charged BSA prefers to aggregate at the interior of artificial crevice due to electrostatic interaction with the concentrated metallic cations in the crevice. In return, the non-uniform BSA adsorption can decrease the crevice corrosion susceptibility of the Ti6Al4V implant material, even though the presence of BSA accelerates the dissolution of passive films. For the Ti6Al4V alloys with artificial crevice, stable localized corrosion occurs after 96 h of immersion in the PBS free of BSA while no stable localized corrosion can be determined in the presence of 4% BSA. It is deduced that the presence of BSA can reduce the surface potential discrepancy between the crevice interior and the crevice exterior. The disclosed mechanism of albumin-corrosion interaction is vital to the localized corrosion control of metallic implants in clinical use.

Defining and visualizing the three-dimensional (3D) structures of pharmaceuticals provides a new and important tool to elucidate the phenomenal behavior and underlying mechanisms of drug delivery systems. The mechanism of drug release from complex structured dosage forms, such as bilayer osmotic pump tablets, has not been investigated widely for most solid 3D structures. In this study, bilayer osmotic pump tablets undergoing dissolution, as well as after dissolution in a desiccated solid state were examined, and visualized by synchrotron radiation micro-computed tomography (SR-μCT). In situ formed 3D structures at different in vitro drug release states were characterized comprehensively. A distinct movement pattern of NaCl crystals from the push layer to the drug layer was observed, beneath the semi-permeable coating in the desiccated tablet sample. The 3D structures at different dissolution time revealed that the pushing upsurge in the bilayer osmotic pump tablet was directed via peripheral “roadways”. Typically, different regions of the osmotic front, infiltration region, and dormant region were classified in the push layer during the dissolution of drug from tablet samples. According to the observed 3D microstructures, a “subterranean river model” for the drug release mechanism has been defined to explain the drug release mechanism.

Gel polymer electrolytes (GPEs) are one of the promising candidates for high-energy-density quasi-solid-state lithium metal batteries (QSSLMBs), for their high ionic conductivity and excellent interfacial compatibility. The comprehension of dynamic evolution and structure-reactivity correlation at the GPE/Li interface becomes significant. Here, in situ electrochemical atomic force microscopy (EC-AFM) provides insights into the LiNO3-regulated micromechanism of the Li plating/stripping behavior upon cycles in GPE-based LMBs at nanoscale. The additive LiNO3 induces the formation of amorphous nitride SEI film and facilitates the Li+ ion diffusion. It stabilizes a compatible interface and regulates the Li nucleation/growth at steady kinetics. The deposited Li is in the shape of chunks and tightly compact. The Li dissolution shows favorable reversibility, which guarantees the cycling performance of LMBs. In situ AFM monitoring provides a deep understanding into the dynamic evolution of Li deposition/dissolution and the interphasial properties of tunable SEI film, regulating the rational design of electrolyte and interfacial establishment for GPE-based QSSLMBs.

Polystyrene (PS) is rich in plastic materials, but it produces a large amount of waste every year, causing a huge burden on the environment. Although PS plastic is the source of a common "white pollution" in daily life, it still has a high utilization value. At the same time, the flammability of PS material determines that it cannot be applicated in places where fire accidents occur frequently. As a result, its application has been greatly limited. In order to realize the efficient utilization of waste PS and broaden its scope of application, PS was modified by hyper-crosslinking in order to improve its fire-retardant performance. In this method, the PS solution with high purity was obtained by dissolving waste PS foam with 1,2-dichloroethane (DCE), and then the hyper-crosslinked polymer with high specific surface area was prepared by adding cross-linking agent formaldehyde dimethyl acetal (FDA) and a Lewis-acid catalyst ferric chloride (FeCl3). Further studies showed that the effects of the amount of cross-linking agent FDA, catalyst FeCl3 and PS on the reaction products were different. In addition, compared the as-prepared fire-retardant materials with PS foam from the aspects of flame retardancy and thermal insulation, it can be concluded that the fire-retardant performance of the materials prepared by this method has been significantly enhanced. And it is proved that this method is feasible towards the preparation of a large number of fire-retardant composite materials by using a scale-up experiment.

Chloride ion batteries (CIB) are considered to be one of the most promising energy storage devices. As cathode materials for CIBs, metal chlorides have many advantages, such as high theoretical energy density, abundant elemental resources and ideal discharge voltage plateau. However, the dissolution and huge volume change of metal chlorides during cycling lead to considerable short lifespan, which limits their potential application for CIBs. Herein, the bismuth chloride nanocrystal is confined in mesocellular carbon foam matrix by a new vacuum impregnation approach. The mesocellular carbon foam with large interconnected pores (15.7 or 23.2 nm) may buffer the large volume variation of bismuth chloride during charge and discharge, giving rise to significantly enhanced electrochemical performance. The as-prepared bismuth chloride@mesocellular carbon foam cathode delivered an initial discharge capacity of 298 mAh/g and a reversible capacity of 91 mAh/g after 60 cycles. In contrast, the pure bismuth chloride cathode almost cannot discharge after 30 cycles. This is the first report that the metal chloride cathode can achieve a prolonged cycling in CIBs.

LiNi0.5Co0.2Mn0.3O2 (NCM523) cathode materials can operate at extremely high voltages and have exceptional energy density. However, their use is limited by inherent structure instability during charge/discharge and exceptionally oxidizing Ni4+ at the surface. Herein, we have developed a citrate-assisted deposition concept to achieve a uniform lithium-conductive LiNbO3 coating layer on the NCM523 surface that avoids self-nucleation of Nb-contained compounds in solution reaction. The electrode–electrolyte interface is therefore stabilized by physically blocking the detrimental parasitic reactions and Ni4+ dissolution whilst still maintaining high Li+ conductivity. Consequently, the modified NCM523 exhibits an encouraging Li-storage specific capacity of 207.4 mAh g−1 at 0.2C and 128.9 mAh g−1 at 10C over the range 3.0–4.5 V. Additionally, a 92% capacity retention was obtained after 100 cycles at 1C, much higher than that of the pristine NCM523 (73%). This surface engineering strategy can be extended to modify other Ni-rich cathode materials with durable electrochemical performances.

Further understanding of the redox process of lithium polysulfides (PSs) on carbon surface is helpful to design Li/S batteries with better performance. “Shuttle mechanism” can explain the low coulomb efficiency and self-discharge of a Li/S battery, but it cannot explain the fact that battery performance is closely affected by electrolyte volume and sulfur load. This paper aims to reveal main redox process of PSs on surface of carbon by examining cathodic behavior with different electrolyte volume and sulfur load. SEM photos and Impedance Spectra of cathode before and after 1st discharge were compared, it was found that the discharge process is the continuous dissolution of sulfur composited with carbon into the electrolyte to form PSs, at the same time, PSs re-precipitates sulfur on the surface of cathode through disproportionation reaction to form a solid film. CV curves showed that the solid film passivates electrode, and the electrode is activated only when potential sweeps negatively and Li2S is generated. When lean electrolyte is used, there is fluctuation in CV curves, which proves that the dissolution-reprecipitation of sulfur is the main process of cathode. The discharge-charge curves of cathodes with different sulfur load were compared, it was found that there is wavy fluctuation in the discharge curve with high sulfur load, which proves again that the sulfur reaction dominates the electrode process.

SnO2 powders with four distinct morphologies of prismoids, hollow rhomboidal tubes, solid rhomboidal rods, and needles have been prepared through morphology-conserved transformation from SnC2O4 precursors. The SnC2O4 precursors were synthesized by a facile oxalate precipitation method. A controllable periodic bond chain (PBC) growth was found to be critical for the formation of these SnC2O4 samples. In the case of forward titration, SnC2O4 prismoids were generated because the formed Sn3O(OH)2SO4 was attached on { 1 ( _ ) 01} polar facets and inhibited the PBC growth along the c axis. By contrast, in the case of reverse titration, SnC2O4 samples preferably formed one-dimensional shapes. Dissolution and ripening were observed during the formation of hollow tubes in the case of low molar ratio of Sn2+ to C2O42−. Further, the formation of SnC2O4 needles was ascribed to the selective coordination of polyvinylpyrrolidone (PVP) on the side surface. The as-prepared SnO2 powders were used as reinforcement of Ag–SnO2 electrical contact materials, and a good adhesion was observed at the Ag (111)/SnO2 (200) interface. Further, the characterization results revealed that the sample reinforced by SnO2 tubes (with one-dimensional shape and hollow structure) had the lowest degradation rate under cathode arc erosion, which might be attributed to its good resistance to the dual action (heat and force) of cathode arc.

The super-structured nanodimensional apatitic particles have been limited explored for therapeutic applications. Furthermore, ion substituted super-structured nanodimensional apatitic particles have been rarely attempted, which motivated the present investigation. In the present work, F − and Cl − substituted hydroxyapatite (HAP) prepared via a facile and economical one-pot hydrothermal route were characterized for their structural, morphological and bioactive properties. The F − and Cl − anions (1 wt%) were individually substituted in hierarchically assembled nanostructured apatitic (HANA) particles and produced fluorine substituted Hydroxyapatite (FHAP) and chlorine substituted Hydroxyapatite (ClHAP) HANA particles, respectively. Besides comprehensive characterization, particles were systematically tested for their in-vitro ionic dissolution and drug-carrying abilities. Both FHAP and ClHAP nanoparticles exhibited monolithic apatitic structure, novel spherical morphology having substituted elements, mesoporous large surface area, and pore-volume with high thermal stability. Furthermore, both particles exhibited superior in-vitro bioactivity ability. Besides it, both FHAP and ClHAP nanoparticles exhibited superior drug loading and sustained drug release characteristics. Thus, this study presented the potentials of novel particle shapes with superior bioactivity and drug-carrying abilities, making them suitable for multipurpose therapeutic applications, including tissue regeneration and drug-carrying agents.

Frosted glass takes considerable research attention due to its simple preparation process and wide application prospect. Herein, acid dissolving salt solution chemical etching method was used to prepare anti-glare (AG) and anti-reflection (AR) glass, and the relationship between etching time and surface crystallization under the constant temperature and the same acid concentration was explored. Based on which, the chemical reaction mechanism was clarified, and the dynamic model of the particle growth of the surface of the etched glass was fitted. The results indicated that with the prolongation of the etching time, the content and size of the insoluble fluorosilicate particles formed on the glass surface increased, and the growth of crystals conformed to the power-law model. Due to the appropriate amount and size of the precipitated insoluble fluoride salts, a light trapping structure was formed on the glass surface to capture incident light so that the transmittance of the glass was increased to a certain extent, and the specular reflection of the surface was effectively transformed into diffuse reflection, achieving an anti-glare effect. The glass etched in the frosting solution with pH = 3 for 15 min showed the best optical properties, with the transmittance of 89%, while the average light reflectance was reduced by 75%. It provides the possibility for the protection of historical buildings.

WS2 with layered graphite-like structure as anode for sodium ion batteries has high specific capacity. However, the poor cycling performance and rate capability of WS2 caused by the low electronic conductivity and structure changes during cycles inhibit its practical application. Herein, metallic phase (1T) WxMo1−xS2 (x = 1, 0.9, 0.8 and 0.6) with high electronic conductivity and expanded interlayer spacing of 0.95 nm was directly prepared via a simple hydrothermal method. Specially, 1T W0.9Mo0.1S2 as anode for sodium ion batteries displays high capacities of 411 mAh g−1 at 0.1 A g−1 after 180 cycles and 262 mAh g−1 at 1 A g−1 after 280 cycles and excellent rate capability (245 mAh g−1 at 5 A g−1). The full cell based on Na3V2(PO4)2O2F/C cathode and 1T W0.9Mo0.1S2 anode also exhibits high capacity and good cycling performance. The irreversible electrochemical reaction of 1T W0.9Mo0.1S2 with Na ions during first few cycles results in the main products of W-Mo alloy and S. The strong adsorption of W-Mo alloy with polysulfides can effectively suppress the dissolution and shuttle effect of polysulfides, which ensures the excellent cycling performance of 1T W0.9Mo0.1S2.

The O2 permeation barrier across the nanoscale ionomer films on electrocatalysts contributes to a major performance loss of proton exchange membrane (PEM) fuel cells under low Pt loading. Enhancing O2 transport through the ionomer films is essential for developing low Pt loading catalyst materials in high-performance PEM fuel cells. This study found that adding an ionic liquid (IL) can effectively mitigate the dense ionomer ultrathin sublayer formed on the Pt surface, which severely hinders O2 transport to the catalyst sites. The molecular dynamics simulation results show that adding the IL significantly alters the ionomer ultrathin sublayer structure by inhibiting its tight arrangement of perfluorosulfonic acid chains but scarcely impacts the ultrathin sublayer thickness. Additionally, the IL addition provides a larger free space for O2 dissolution in the ultrathin sublayer. Consequently, due to IL molecules’ presence, the O2 density in the ultrathin sublayer on the Pt surface is improved by an order of magnitude, which will benefit the catalytic efficiency, and the O2 permeation flux across the ionomer film is increased by up to 8 times, which will reduce the O2 transport loss of the catalyst layer.

The high-Ni layered metal oxide, LiNi0.8Co0.1Mn0.1O2 (LNCM811), has received widespread attention in the energy field because of its high specific capacity, but its large-scale applications are hindered due to severe capacity fading. Herein, a uniform and thin Li2O–B2O3–LiBr-glass (LBBrO-glass) coating was deposited on LNCM811 by a liquid-phase coating and thermal treatment method. The experimental results suggested that the LBBrO-glass coating acted as a protective layer that inhibited transition metal dissolution and side reactions, which helped improve the electrochemical properties of LNCM811. Remarkably, after 200 cycles, the 2 wt% coating (LBBrO@LNCM-2) delivered a superior capacity retention of 88.9%, while only 71.8% was obtained for the pristine material (LNCM811). The discharge capacity of LBBrO@LNCM-2 was 163.5 mAh g−1 at 5C, while it was only 139 mAh g−1 for the pristine material.

Nano-zirconia has been widely applied due to its excellent physical and chemical properties (e.g., high strength, corrosion resistance, oxygen ion conductivity). Existing preparation methods of nano-zirconia tend to require long reaction time, and the sizes of final particles are large with uneven distributions. Sub-/supercritical hydrothermal synthesis of nanoparticles is favored by researchers owing to controllable reaction process, uniform particle size distribution, good reproducibility, short reaction time, high conversion rate and harmlessness to environment. In this paper, the characteristics and mechanisms of dissolution, crystallization and growth of nano-zirconia during sub-/supercritical hydrothermal synthesis are systematically reviewed. The influences of process and material parameters on the size and purity of particles are analyzed. Then, the reaction mechanism and product phase transition mechanism during hydrothermal synthesis of zirconia are summarized to provide a theoretical reference for the oriented preparation. Finally, the improvement and commercialization of sub-/supercritical hydrothermal synthesis technology are evaluated, and the future research topics are proposed.

PtNi alloy nanoparticles display promising catalytic activity for oxygen reduction reaction (ORR), while the Ostwald ripening of particles and the dissolution/migration of surface atoms greatly affect its stability thus restricting the application. Herein, the WOx-surface modified PtNi alloy nanowires (WOx-PtNi NWs) exhibiting enhanced ORR catalytic property is reported, which has high aspect ratio with the diameter of only 2 ∼ 3 nm. It is found that the WOx-PtNi NWs shows a volcano relationship between the ORR activity and the content of WOx. The WOx-(0.25)-PtNi NWs has the best performance among all the synthesized catalysts. Its mass activity (0.85 A mg−1Pt) is reduced by only 23.89% after 30k cycles durability test, which is much more stable than that of PtNi NWs (0.33 A mg−1Pt, 45.94%) and Pt/C (0.14 A mg−1Pt, 57.79%). Hence this work achieves an effective regulation of the ORR activity for PtNi alloy NWs by the synergistic effect of WOx on Pt.

Despite its cost-effectiveness and intrinsic safety, the aqueous zinc-iodine battery is still struggling with the rapid performance degradation arising from the uneven deposition of the zinc anode and the dissolution of the iodine cathode. An effective solution of addressing the above issues simultaneously is urgently needed. Here we propose a strategy of using one porous carbon to modify the zinc anode and immobilize the iodine active materials. Zinc citrate-derived porous carbon is selected as a study model. The conductive porous carbon can not only greatly reduce the zinc nucleation barrier, and guide a uniform deposition of zinc ions, but also notably suppress the dissolution of iodine species and enhance the reaction kinetics. As a consequence, the optimized zinc-iodine battery exhibits capacity retention of 88.1% after 3000 cycles at 12C, finishing a cycle within 5 min.

Aragonite, one of the most common biological calcium carbonate minerals, is widespread in marine plankton and neritic sediments (e.g., accounting for 89% of pelagic calcification of CaCO3 in the surface ocean). Its dissolution directly affects the export fluxes of CaCO3 in seawater. The aragonite dissolution in the ocean correlates with the increase of partial pressure of carbon dioxide and is pertinent to acidic biomolecules. However, aragonite dissolution in seawater with acidic biomolecules has been overlooked, and the interaction mechanism is unclear. In-situ atomic force microscopy (AFM) was employed to observe the dissolution features of aragonite (110) growth surfaces in succinic acid (SUC, HOOC-CH2-CH2-COOH) solutions. The results demonstrate that (1) both the morphologies and spreading rates of the etch pits formed on aragonite (110) surfaces are altered by the interactions between SUC molecules and the surfaces; (2) the [1-11] and [-111] steps of the etch pits on aragonite (110) surfaces in SUC solutions are kinetically controlled; (3) dissolution rates of aragonite (110) surfaces are proportional to SUC concentrations, which is attributed to the strong complexation between SUC molecules and surface-bounded Ca atoms (≡Ca+); (4) etch pits morphologies of aragonite (110) and calcite (10.4) surfaces are different in SUC solutions, and the spreading rates of the etch pits of the former are one to two orders of magnitude lower than those of the latter. Furthermore, aragonite is found to be more sensitive to SUC molecules than calcite, suggesting that dissolving aragonitic materials could be more easily affected by circumambient biomolecules than dissolving calcitic materials. In seawater that contains organic molecules, the dissolution fluxes of aragonite could be much slower than those of calcite. These findings not only reveal the site-specific interactions between SUC molecules and the ≡Ca+ on aragonite (110) surfaces but also emphasize its implication for the oceanic aragonite dissolution fluxes.

The presence of hydrous minerals in carbonaceous chondrites has been considered as an important evidence for the former presence of liquid water in parent asteroids. However, the evolution of water–rock reactions in hydrous asteroids remains not well constrained. Here, we conduct water–rock type experiments and chemical equilibria calculations under low-temperature hydrothermal and reducing conditions to investigate the alteration process and secondary mineral assemblages of chondritic rock in the earliest alteration stage. Using synthetic chondrite (mixtures of olivine (forsterite95), orthopyroxene (enstatite95), silicate glass, troilite and Femetal) as a starting material, our experiments were conducted at temperatures of 25°C–80°C for time periods between 1 to 460 days at a water-to-rock mass ratio of 10. A combination of X-ray diffraction (XRD) and transmission electron microscope (TEM) analyses revealed that the primary secondary phases consisted of pyrrhotite, an amorphous SiO2-rich phase and saponite at 80°C, while the secondary phase consisted of an amorphous SiO2-rich phase and saponite at 25°C. At both temperatures, the SiO2-rich phases and saponite densely covered the surface of the primary phases. The Fe/Mg ratios of saponite and amorphous SiO2-rich phases showed clear difference between 80°C and 25°C. Saponite that was formed at 80°C was richer in Fe than the initial silicate phases, and the highest Fe/Mg ratios were obtained in the saponite encrusting the troilite and Femetal. These results suggest that the Fe distributed from the troilite and Femetal induced the formation of Fe-rich saponite. Some of the secondary minerals observed from our alteration experiments were consistent with those expected by chemical equilibria calculations. However, the formation of serpentine, the dominant secondary mineral expected from chemical equilibria calculations, was not observed in our experiments up to 460 days, probably because the preferential dissolution of SiO2-rich silicate glass in the earliest stage of alteration induced the formation of saponite rather than serpentine. The secondary mineral assemblage and its morphological characteristics, as observed by our alteration experiments, showed similarities with carbonaceous chondrites such as CM2 and CO3 chondrites. This alteration might be explained by water–rock reactions at low temperatures and by the short time alteration. These findings better constrain the temperatures and timescales of aqueous alterations in hydrous asteroids, as well as the role of water in the early solar system bodies.

Mesoporous silica nanoparticles (MSN) are promising drug vectors due to their high drug loading capacities, degradability under biologically relevant conditions. The dissolution of MSN has been the focus of several recent studies, most of which have, however, been carried out in the absence of proteins, and do therefore not reflect the conditions prevailing during in vitro or in vivo administration of the particles. Furthermore, typically the dissolution studies are limited with respect to the range of MSN concentrations applied. Here, we report results related to the dissolution kinetics and structural particle evolution for MCM-48 MSN carried out in the presence of proteins, and where the particle concentration has been used as a parameter to cover typical concentrations used in in vitro and in vivo studies involving MSNs. Proteins adsorbing to the MSN surface form a diffusion limiting layer that leads to the intermediate formation of core-shell structured particles upon dissolution. Here, the protein concentration controls the kinetics of this process, as the amount of protein adsorbing to the MSN increase with increasing protein concentration. The results thus also imply that the MSN dissolution kinetics is faster under normally applied in vitro conditions as compared to what can be expected under full serum conditions.

Two-dimensional (2D) ZnSnO3 is a promising candidate for future gas sensors due to its high chemical response and excellent electronic properties. However, the preparation of 2D ZnSnO3 nanosheets by utilizing soluble inorganic salts and nonorganic solvents remains a challenge. In this work, 2D ZnSnO3 was synthesized via a facile graphene oxide (GO)-assisted co-precipitation method, in which inorganic salts in the aqueous phase replaced metal organic salts in a non-aqueous system. Meanwhile, a “dissolution and recrystallization” mechanism was proposed to explain the transformation from 3D nanocubes to 2D nanosheets. In comparison, the 2D ZnSnO3 nanosheets showed a higher response to formaldehyde (HCHO) at low operating temperature (100 °C). The response (Ra/Rg) of the 2D ZnSnO3 sensor to 10 ppm HCHO was as high as 57, which was approximately 5 times the response of the ZnSnO3 nanocubes sensor. However, the ZnSnO3 nanocubes sensor showed better gas sensing performance to ethanol at high temperature (200 °C). Different gas-sensitive properties were attributed to the different gas diffusion and adsorption processes caused by the morphology and nanostructure. Moreover, both sensors could detect either 0.1 ppm HCHO or ethanol at their optimum operating temperature. This work presents a relatively economical method to prepare 2D compound metal oxides, provides a novel “dissolution and recrystallization” mechanism for 2D multi-metal oxide preparation, and sheds light on the great potential of high-efficiency HCHO and/or ethanol gas sensors.

S@pPAN has become promising cathode materials in rechargeable batteries due to its high compressed density, low E/S ratio, no polysulfide dissolution, no self-discharge, and stable cycling. However, it is a big challenge to enhance its sulfur content which determines its practical specific capacity. Herein, we prepare crosslinked PAN as precursor, leading to effective enhancement of sulfur content up to 55 wt% and a reversible specific capacity of 838 mAh g-1composites at 0.2C. Because of the microporous structure and high specific area, crosslinked PAN provides more space to accommodate sulfur molecule and improve the interfacial reaction of S@pPAN as well. This work provides a promising direction to design S@pPAN for lithium sulfur batteries with high energy density.

Bioactive glasses (BGs) incorporating metallic ions to impart antibacterial activity and stimulation of osteogenesis and angiogenesis are promising candidates for bone tissue engineering. Silicate BGs of the 45S5 composition (45 SiO2, 24.5 Na2O, 24.5 CaO, 6 P2O5, (wt%)) crystallize readily during the high temperature processing of porous scaffolds. The crystallization slightly suppresses the bioactivity and dissolution of the glass. Structural changes during the high-temperature processing of metal ion-doped 45S5 BGs are challenging since metal ions may affect the formation of crystalline phases during thermal treatment. In this study, we investigated the effect of Cu on structural changes during the sintering of Cu doped 45S5 BG (Cu-45S5). The Cu-45S5 BG was sintered at 900 °C and 1050 °C for 1 hour, and the resultant microstructures were investigated using X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), including elemental distribution mappings from energy-dispersive X-ray spectroscopy (EDXS), and X-ray nano-computed tomography (nano-CT). XRD patterns of thermally treated samples indicate the formation of combeite and rhenanite as crystalline phases. Besides the crystalline fraction, a residual glassy phase is also present, which is enriched with Na and P ions. The results reveal that the crystallinity of Cu-45S5 glass-ceramics can be adjusted over a range of 70–78% by applying appropriate heat treatment profiles. Moreover, the size of the crystals increases with increasing temperature under the investigated conditions. Cu is found to be localized in the residual glassy phase, together with Si and Na, which has an effect on the release of Cu ions in physiological environments.

Studies on the formation and evolution of the solid electrolyte interface (SEI) film under different ambient temperatures are important to understand the failure behavior of lithium-ion batteries (LIBs). Herein, in-situ electrochemical impedance spectroscopy (EIS) test is performed on the whole discharge process of Si@Graphite@C/Li cell at 0, 25 and 55 ℃, respectively. Combining with scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy characterizations, it is found that the SEI film undergoes a complicated evolution process of pre-formation, self-improvement and gradual decay in succession at 25 ℃. Besides, due to the dissolution of organo-alkyl lithium at high temperature, the formed film is mainly composed of LiF, Li2CO3 and other inorganic salts, which helps to decrease the impedance. However, the electrolyte is consumed continuously on the new exposed interface, leading to the degraded performance of the cell. Moreover, the dynamic properties of Li+ ions are poor at low temperature, though the migration ability of Li+ ions in the solid phase can be improved as the cycle goes on. Therefore, the development and application of in-situ EIS technology are expected to become an important means to explain the electrochemical performance of batteries.

MnO2-based aqueous Zn-ion batteries (ZIBs) hold great promising for large-scale energy storage applications owing to their safe and sustainable nature. However, rapid capacity decay under high depth of discharge limits the applications of MnO2 cathodes. In the meantime, the reaction chemistry and degradation process of MnO2 cathodes cannot be fully understood, leading to improvement of their cycling stability lacks of robust methods. Herein, ZIB performances of MnO2 polymorphs are investigated to disclose their detailed reaction chemistry and degradation mechanisms. Ex situ characterizations at different cycles exhibit evolution of active materials (original MnO2→Mn2+→birnessite→ZnMn2O4/Mn3O4) and coexisted reactions from co-insertion, dissolution/deposition and chemical conversion mechanisms. Variational contributions from these intermediate products and different reaction mechanisms cause fluctuated performance during cycling. Initial performance activation is from enhanced activity of birnessite, while the degradation is caused by its conversion to electrochemically inactive ZnMn2O4 and Mn3O4. By optimizing tunnel structures, it is found that R-MnO2 shows low manganese dissolution with its reaction mainly achieved by intercalation/extraction of Zn2+/H+, and theoretical calculations verify its low Jahn-Teller distortion at discharged state. This specific property circumvents conversion of R-MnO2 to metastable birnessite, giving rise to a stable capacity under high depth of discharge.

Surface engineering of metal–organic frameworks (MOFs) with a mesoporous silica coating can improve MOF mechanical properties and provide an easy way to decorate MOF nanoparticles with organic or biological molecules though silane chemistry or electrostatic interactions, while retaining open access to MOF porosity. Silica coating would be highly beneficial for employing MOFs in a wide range of applications such as catalysis or drug delivery. However, obtaining a stable, controlled core–shell structure using MOF nanoparticles as seeds is challenging because of their intrinsic chemically labile nature. Here we analyze the factors that destabilize the core of the Zeolitic Imidazolate Framework-8 (ZIF-8) MOFs during the sol–gel deposition of a mesoporous silica shell causing a partial or total etching of the MOF material. Silicates in solution are found to scavenge Zn2+ ions removing them from the ZIF structure and causing a partial or complete dissolution of the ZIF seed. By carefully tuning the silicate concentration in solution simultaneous control can be obtained over both the ZIF-8 dissolution and the silica condensation kinetics, resulting in the growth of a uniform mesoporous silica shell while preserving the integrity of ZIF-8. The core–shell nanoparticles obtained show a compact core shell structure with no gap between the MOF core and the silica shell, even after calcination, while the crystalline ZIF-8 structure is retained. Overall, a general synthetic approach is presented for producing nanocomposite core–shell materials which can be applied to other MOF labile seeds to design new hierarchical materials.

Molybdenum disulfide (MoS2) is a promising anode material for lithium-ion batteries (LIBs) because of its high theoretical capacity. But its rapid capacity decay due to poor conductivity, structure pulverization, and polysulfide dissolution presents challenges for practical applications. In this work, an innovative cationic surfactant templating route to one-step synthesizing epitaxial few-layer MoS2@N-doped carbon (EF-MoS2@NC) core–shell hollow structures is developed via an electrostatic interaction S+X−I+ pathway. Compared with general hard-template strategies, the soft-template method proposed here is simplified, avoiding the cumbersome coating and template removal process. The internal hollow space and outer NC protective layer can accommodate the large volumetric expansion of MoS2 and preserve the structural integrity of the electrode preventing polysulphide dissolution. When evaluated as anode materials for LIBs, the core–shell EF-MoS2@NC hollow spheres achieve a high discharge capacity of 928 mA h g−1 after 100 cycles at 0.1 A g−1. More importantly, a reversible capacity of 829 mA h g−1 could be obtained at 1.0 A g−1 after 1000 cycles, which demonstrates good stability.

Copper is a most widely used substrate for Li deposition and dissolution in lithium metal anodes, which are complicated by the formation of solid-electrolyte-interphases (SEIs) whose physical and chemical properties can affect Li deposition and dissolution significantly. However, initial Li nucleation and growth on bare Cu creates Li nuclei that only partially cover the Cu surface so that SEI formation could proceed not only on Li nuclei but also on the bare region of the Cu surface with different kinetics, which may affect the follow-up processes distinctively. In this paper, we employ in-situ atomic force microscopy (AFM) together with X-ray photoelectron spectroscopy (XPS) to investigate how SEIs formed on Cu surface, without Li participation, and on the surface of growing Li nuclei, with Li participation, affect the components and structures of the SEIs, and how the formation sequence of the two kinds of SEIs along with Li deposition affect subsequent dissolution and re-deposition processes in a pyrrolidinium-based ionic liquid electrolyte containing small amount of water. Nanoscale in-situ AFM observations show that sphere-like Li deposits may have differently conditioned SEI-shells, depending on whether Li nucleation is precedent with formation of the SEI on Cu. Models of integrated-SEI shells and segmented-SEI shells are proposed to respectively describe SEI shells formed on Li nuclei and the SEI shells sequentially-formed on Cu and then on Li nuclei. “Top-dissolution” are observed for both types of shelled Li deposits, but the integrated-SEI shells only show wrinkles which can be recovered upon Li re-deposition while the segmented-SEI shells are apparently top-opened due to mechanical stresses introduced at the junctions of the top regions and become “dead” SEIs which forces subsequent Li nucleation and growth in the interstice of the dead SEIs. Our work provides insights on the impact mechanism of SEIs on Li deposition and dissolution on foreign substrates, and reveals that SEIs could be more influential to Li dissolution and spatial integration of SEI shells on Li deposits is important to improving the reversibility of deposition and dissolution cycling.

Organic electrode materials with environmentally friendly, design flexibility at the molecular level are promising substitutes for inorganic intercalation materials as cathode for SIBs. However, traditional electrode materials usually perform poor cycling stability and rate performance, mainly due to the dissolution in electrolytes and low electronic conductivity. Herein, conjugated porous polyimide poly(2,6-diaminoanthraquinone) benzamide (CP-PDAB), was prepared from 2,6-diaminoanthraquinone and pyromellitic dianhydride by a simple polycondensation reaction. The obtained CP-PDAB has disordered aggregates with porous and loose structure, facilitating the penetration of electrolyte and volume change during charging/discharging. And the constructed conjugated skeleton with electron delocalization is beneficial for structural stability, insolubility in electrolyte and high electronic conductivity. When evaluated as cathode for sodium ion batteries, it can retain a high reversible discharge capacity of 141 mAh g-1 at 500 mA g-1 for 100 cycles, and can maintain the high specific capacity of 71 mAh g-1 at 10 A g-1 after 500 cycles. This work demonstrates the potential application of organic materials containing conjugated skeleton, porous and loose structure, and multiple redox active units for next generation electrochemical energy storage devices.

Titanium dioxide (TiO2) thin films are prepared on various substrates like glass and silicon wafers by spray pyrolysis method. The spray solution is prepared by dissolving titanium-tetra isopropoxide (TTIP) in ethanol. Optical, structural and dielectric properties of these films are studied by the transmittance spectra, X-ray diffraction (XRD), atomic force microscopy (AFM), capacitance–voltage (C-V) characteristics, respectively. TiO2 metal oxide semiconductor (MOS) capacitors are fabricated using TiO2 as a dielectric medium. C-V plots are analyzed to determine the dielectric constant (er) of TiO2 film. The dependance of er of the TiO2 films with the substrate temperature has been investigated.

High-performance polymeric membrane technology is rapidly developing worldwide with the introduction of new materials and processes. Considerable research efforts are being made to establish a polymer membrane that can be used for ultrafiltration (UF) or nanofiltration (NF) applications. The development of modified polyamide-66 polymer and its compatibility in wastewater are essential elements in the quest for advances and improvements in membrane technology. The optimized conditions for membrane synthesis are critical in making it commercially viable. Response Surface Methodology (RSM) was used to find the optimum dissolution of polyamide-66 in formic acid. A model was developed and validated with experimental data, and it showed good agreement with R2 0.9984. The optimized condition for minimizing viscosity was determined. For minimum viscosity (3.64 cp), the optimum temperature and wt.% were 20 ?C and 0.6, respectively.

Lithium metal is an ideal anode for high-energy-density rechargeable batteries. However, its practical applications are hindered by the low Coulombic efficiency (CE) caused by the dendrites’ growth and the fragile SEI. Both ionic solvation behavior and SEI formation strongly affect the stability of the Li metal anode in a rechargeable battery. In this paper, 1,3-dioxolane (DOL), the well-known weak solvating capability and good SEI formation, was used as the solvent in its-fluorinated ether (TTE) blends. DOL reduced the cation-solvents interaction but reinforced the cation-anions coordination, lowering the Li plating-stripping overpotential. The addition of TTE significantly reshaped the solvation structure of Li-ion in the mixed solvent of DOL-TTE in comparison to the concentration effect. Specifically, the high TTE contents improved the electrochemical stability of the electrolyte, generated more anion-derived SEI, and resulted in the uniform Li plating-stripping that correlated with the solvation structure of more ionic aggregates less free solvents and anions. Apart from stabilizing Li anode, the decreasing free solvents in DOL-TTE (1:2) electrolytes prevented the rapid capacity decline of Li-SPAN cells from the dissolution and loss of LiPSs, obtaining 92% capacity retention and 99.77% average CE after 100 cycles.

The paper reports a comprehensive review of the performance of nanoporous gas-liquid polypropylene membrane contactor with NaOH absorbents for removal of H2S and CO2 components from the gas streams. The experiments at different operation conditions, including variation of acid gas content in a feed stream, alkali concentration in absorbent, gas and liquid absorbent volume flow rates, absolute and gas-liquid differential pressures are discussed as a function of the absorbent saturation levels. In-liquid diffusion of components and gas/membrane contact times were determined as main governing factors limiting contactor efficiency. Mass transfer rates of acid gas removal on the membrane contactor over 3 × 10−3 mol/(m2 × s) for CO2 and 7.5 × 10−3 mol/(m2 × s) for H2S were attained. Ultimate processed gas quality with H2S content below 5 ppm and CO2 content below 0.01% was achieved at the contactor performance over 7 m3/(m2 × h) and initial acidic gas content of 2%, while achieving a membrane packing density in the contactor over 3000 m2/m3. The paper also provides an experimentally-proven theoretical model for calculating removal efficiency and residual acid gas partial pressures depending on the membrane parameters and operation conditions. It is shown, the mass transfer coefficient and removal efficiency differ significantly for H2S and CO2 due to the difference in dissolution mechanism involving kinetically limited deprotonation reaction of solvated water in case of CO2(aq) while engaging direct deprotonation of H2S. This allows to attain residual partial pressure of H2S in retentate stream equal to the equilibrium pressure above the absorbent solution, while CO2 residual pressure exceeds an equilibrium value few orders of magnitude. The effect has been successfully utilized for the selective removal of H2S from both CO2 and H2S-containing mixtures with H2S/CO2 selectivity exceeding 1500.

The wetting of 3% yttria-stabilized zirconia (YSZ) by Sn–8Zr, Sn–4Zr–4Ti, and Sn–8Ti alloys was studied at 800–900 °C. Both Zr and Ti improve the wettability via the formation of reaction products and adsorption. In the systems containing Zr additives in the alloys, ZrO2-x precipitates preferentially, and the wettability is dominated by interface adsorption. An anomalous temperature dependence was found in the final wettability of these systems owing to the decrease in adsorption with an increase in the temperature. The spreading dynamics are controlled by the dissolution of Zr, followed by the formation of a wetting ridge. The wettability of the Sn–8Ti/YSZ system is dominated by the precipitation of reaction products (Ti2O3 and Ti11.31Sn3O10). The reaction kinetics is the limiting factor for spreading in Sn–8Ti/YSZ, and the adsorption at the interface significantly decreased the energy barrier for wetting.

Traditional hard/soft template approaches to hollow structures suffer from tedious procedures and time-consuming. Compare to these methods, self-template approaches usually gain advantages of step-economy. Herein, solid spherical Ni-glycolate/Ni microspheres were initially synthesized by reacting nickel (II) with ethylene glycol at high temperature. The source of nickel (II) has determinable impact on the formation of Ni-glycolate/Ni. Specially, nickel acetate as sources yielded Ni-glycolate/Ni, while nickel nitrate as precursor cannot. The plausible reason for this result can be attributed to the different acidity of the system caused by the dissolution of nickelacetate and nickel nitrate. By reacting with thioacetamide (TAA) under solvothermal condition and heat treatment, the Ni-glycolate/Ni microspheres were further employed as self-template for direct the formation of hollow NiS microspheres. The driving force for converting Ni-glycolate/Ni into hollow NiS could be attributed to Kirkendall effect resulted from the different diffusion rates of nickel ions (from Ni-glycolate/Ni) and sulfur ions from the decomposition of TAA. When applied as electrode material of supercapacitors, the formed hollow NiS microspheres exhibited a specific capacitance of 1674 F/g at 1 A/g with excellent rate capability and cycling performance. The corresponding asymmetric device of NiS//AC delivered a high energy density of 43.3 Wh/kg at the power density of 850.3 W/kg. These achievements pave innovative synthetic approach to hollow structures for many other practical applications.

We encapsulate large Pt shell/Ni core (PtNi) particles with thick and porous nitrogen-doped carbon (N–C) layers, and demonstrate that the thick N–C layers can protect the PtNi particles from dissolution and migration for an extremely long service life through both steric hindrance and chemical bond; in addition, the well mass transfer performance of the porous N–C, the thin Pt shell, and the promotion effects of N–C and Ni on Pt lead to excellent activity of the composite catalyst (N–C/PtNi). As a result, the N–C/PtNi keeps the high oxygen reduction reaction activity value of 962–1080 mA mgPt−1 for 60,000 cyclic voltammetry (CV) cycles and still has a high activity of 265 mA mgPt−1 even after 120,000 CV cycles. Moreover, the N–C/PtNi shows a max power density of 1.24 W cm−2 at cathodic loading of 0.1 mgPt cm−2 in H2–O2 fuel cell under 200 kPa absolute pressure of O2 without performance decrease within 60,000 cycles. Other large noble metal-based particles are believed to gain ultrahigh stabilities and higher activities through performing the similar encapsulation.

Poor dispersion of metal oxide-biomass carbon composite limits its further improvement in electrochemical properties. The study reports synthesis of highly dispersed RuO2-biomass carbon nanocomposite (HD–RuO2–BC). Octyl ammonium salicylate ionic liquid was combined with Ru3+ ion to form Ru-based ionic liquid. Followed by addition of coconut meat, microwave treatment to form homogeneous solution, thermal reduction in N2 and oxidation in air in sequence. The resulting HD–RuO2–BC shows three-dimensional architecture and high Ru loading of 9.2%. RuO2 nanoparticles of 6.2 nm were uniformly dispersed in biomass carbon sheets. Excellent dispersion and small size of RuO2 nanoparticles achieve to a significant synergy between RuO2 and biomass carbon. HD–RuO2–BC electrode gives high capacitance of 907.7 F g−1 at 1 A g−1. The value is more than that of BC (150.6 F g−1) and RuO2 electrodes (584.7 F g−1), verifying that introduction of RuO2 achieves to an obviously enhanced capacitance. The symmetrical flexible supercapacitor exhibits excellent supercapacitor performances, including high capacitance (403.8 F g−1 at 1.0 A g−1), rate-capacity (223.1 F g−1 at 50 A g−1), cycling stability (98.2% capacity retention after 10,000 cycles at 50 A g−1) and energy density (378.7 Wh Kg−1at power density of 5199.2 W kg−1).

Lithium-sulfur (Li-S) batteries are considered to be promising candidates for next-generation storage systems. However, the practical applications are still hindered by the severe capacity decay, mainly caused by the large volume change, polysulfide shuttle and sluggish sulfur conversion kinetics. Herein, hollow urchin-like Mn3O4 (HU-Mn3O4) microspheres as sulfur hosts have been synthesized by the hydrothermal method and calcination treatment, aiming to prevent the polysulfide dissolution (benefiting from the strong polysulfide anchoring effect of Mn3O4) and alleviate the volume expansion of sulfur (benefiting from the special hollow structure). Meanwhile, the urchin-like thorny surface also facilitates the rapid ion/electron transfer and the abundant active sites for the fast sulfur redox kinetics. When used as the sulfur host in Li-S batteries, the S@HU-Mn3O4 cathode delivers a high initial capacity of 1137.4 mAh g−1 with a slow capacity decay of 0.042% after 200 cycles at 0.2 C. Even under the conditions of lean electrolyte (E/S = 7 mL g−1) and low N/P ratio (N/P = 2.1), the S@HU-Mn3O4 cathode still enables a stable cycling performance with a high gravimetric energy density (202 Wh kg cell−1), demonstrating its great potential in the development of future practical Li-S battery materials.