Phosphate Surface Research Articles

Effect of air-particle abrasion and methacryloyloxydecyl phosphate primer on fracture load of thin zirconia crowns: an in vitro study

The study aimed to investigate the effects of airborne-particle abrasion (APA) and 10-methacryloxydecyl dihydrogen phosphate (10-MDP primer) surface treatments on the fracture load of thin zirconia crowns made from 3Y-TZP and 5Y-PSZ zirconia. Eighty full-contour zirconia crowns of 0.5 mm thickness were fabricated from 3Y-TZP and 5Y-PSZ zirconia. Crowns of each material were divided into four groups based on the surface treatment applied to the fitting surface (n = 10): Group 1 (control), Group 2 (10-MDP Primer Only), Group 3 (APA Only), and Group 4 (10-MDP Primer + APA). Crowns were cemented using self-adhesive resin cement and subjected to thermocycling. Fracture load tests were performed using a universal testing machine with a hemispherical indenter. Statistical analysis was performed using one-way ANOVA, Tukey's post hoc test, and independent samples T-test (α = 0.05). The fracture load of 3Y-TZP was significantly higher than 5Y-PSZ crowns across all groups (P ≤ 0.001). Group 1 had the lowest fracture load, while Group 4 had the highest for both materials. In 3Y-TZP, the fracture load of Group 2 increased by 40% (P = 0.002) and Group 3 by 50% (P < 0.001) compared to Group 1. Group 4 showed a 90% increase over Group 1 (P < 0.001). For 5Y-PSZ, fracture load of Group 4 increased by 70% compared to Group 1 (P < 0.001). It was concluded that applying a 10-MDP primer or APA significantly increases the fracture load of thin 3Y-TZP zirconia crowns, with the combination of both treatments yielding the highest values. For 5Y-PSZ, a significant increase in fracture load is observed only when both APA and the 10-MDP primer are used together.

Improvement of the Abrasion and Corrosion Resistance of a Waterborne Epoxy Coating by α-ZrP@PTA-Ce(III) with Dual Corrosion Inhibition Effects.

The introduction of poly(tannic acid) (PTA) and cerium ion [Ce(III)] on the surface of α-zirconium phosphate (α-ZrP) endowed the α-ZrP@PTA-Ce(III)/waterborne epoxy composite coating with enhanced corrosion protection and wear resistance performances. The successful preparation of α-ZrP@PTA-Ce(III) was confirmed through X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectra. PTA improved the compatibility between α-ZrP@PTA-Ce(III) and the waterborne epoxy resin due to the presence of organic groups from tannic acid. The wear resistance test indicated that the incorporation of α-ZrP@PTA-Ce(III) effectively reduced the coefficient of friction and the wear rate. Electrochemical impedance spectroscopy was used to analyze the corrosion protection performance of unbroken coatings and the self-healing ability of scratched coatings. The incorporation of α-ZrP@PTA-Ce(III) improved the protection performace distinctly. In addition, α-ZrP@PTA-Ce(III) endowed the composite coating with dual corrosion inhibition effects, originating from the PTA film, to prevent the penetration of corrosive media and a dense film that came from the Ce(III) cation. The waterborne epoxy system with enhanced corrosion and wear resistance in this paper broadens the application of α-ZrP.

Catalytic recycling of polylactic acid over zirconium phosphate supported WOx active sites

Chemical upcycling of end-of-life plastics is an economically and environmentally feasible way to tackle plastics crisis. Among them, methanol alcoholysis of polylactic acid (PLA) is a promising approach, which can produce methyl lactate (MLA) that can be further converted to lactide to achieve a sustainable development. In this work, a series of WOx/ZrP catalysts with WOx active sites in low coverage and high surface area were synthesized via anchoring WOx species on the surface of zirconium phosphate (ZrP). Characterizations indicated that the strong interaction between WOx and ZrP promoted the formation of WOx active sites in low coverage. In particular, 10 %WOx/ZrP catalyst was highly active and stable for the alcoholysis of PLA plastics under mild conditions due to the abundant WOx active sites and strong acidity. The yield of MLA over 10 %WOx/ZrP catalyst reached 94.5 % within 4 h at 160 °C, which was superior to the performance of traditional solid acids (α-ZrP, HZSM-5, Hβ and Amberlyst-45). In addition, 10 %WOx/ZrP was versatile for the alcoholysis of discarded PLA-based products and could be recycled at least five times. The prominent performance of 10 %WOx/ZrP catalyst and the possible reaction mechanism were discussed.

Apatite Formation on α-Tricalcium Phosphate Modified with Bioresponsive Ceramics in Simulated Body Fluid Containing Alkaline Phosphatase.

Bioresponsive ceramics, a new concept in ceramic biomaterials, respond to biological molecules or environments, as exemplified by salts composed of calcium ions and phosphate esters (SCPEs). SCPEs have been shown to form apatite in simulated body fluid (SBF) containing alkaline phosphatase (ALP). Thus, surface modification with SCPEs is expected to improve the apatite-forming ability of a material. In this study, we modified the surface of α-tricalcium phosphate (α-TCP) using methyl, butyl, or dodecyl phosphate to form SCPEs and investigated their apatite formation in SBF and SBF containing ALP. Although apatite did not form on the surface of the unmodified α-TCP in SBF, apatite formation was observed following surface modification with methyl or butyl phosphate. When ALP was present in SBF, apatite formation was especially remarkable on α-TCP modified with butyl phosphate. These SCPEs accelerated apatite formation by releasing calcium ions through dissolution and supplying inorganic phosphate ions, with the latter process only occurring in SBF containing ALP. Notably, no apatite formation occurred on α-TCP modified with dodecyl phosphate, likely because of the low solubility of the resulting calcium dodecyl phosphate/calcium phosphate composites. This new method of using SCPEs is anticipated to contribute to the development of novel ceramic biomaterials.

Enhancing PA-PBI Composite Membrane with Metal Oxides Incorporation for HT-PEMFC Operating Above 200 oc

High-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) are renowned for their excellent CO tolerance and rapid reaction kinetics [1]. Among the various membrane types, phosphoric acid doped polybenzimidazole (PA-PBI) membranes, phosphoric acd (PA) acts as a proton conductor, facilitating proton transfer through hydrogen bond rearrangement between PA molecules and the PBI backbone [2]. However, the operating temperature of PA-PBI membrane-based HT-PEMFC is constrained by the condensation of PA, limiting their use to below 180 oC and posing a significant challenge for achieving efficient operation above 200 oC.Recent research endeavors have focused on enhancing PA-PBI membranes by incorporating metal oxides to extend their operational temperature range beyond 180 oC. The addition of metal oxides into PA solution leads to the formation of metal hydrogen phosphate, effectively preventing PA evaporation at elevated temperatures ( > 180 oC) and maintaining membrane performance without degradation. Furthermore, the presence of metal oxides facilitates proton transfer to the metal hydrogen phosphate surface, thereby improving ionic conductivity even at temperatures exceeding 200 oC.In this study, we present the synthesis of poly(2,2’-(1,4-phenylene)-5,5’ bibenzimidaozle) (pPBI) composite membranes through an in-situ method, where various metal oxides (SnO2, TiO2, ZrO2) are introduced into the synthesis solution. Through systematic investigation, we evaluate the impact of these metal compounds on fuel cell performance and durability at high temperatures exceeding 200 oC. Our findings shed light on the potential of metal oxide-modified PA-PBI composite membranes for advancing the performance and reliability of HT-PEMFCs in demanding operating conditions.

Nanoplatforms derived from iron dextran combined with ascorbic acid for enhanced photothermal-chemodynamic therapy of tumors

The current limitations of chemodynamic therapy (CDT) are mainly due to the lack of metal ions (Fe2+, Cu+, etc.), glutathione overexpression, and insufficient hydrogen peroxide level in the tumor microenvironment. Here, we constructed a safe and effective nanoplatform (abbreviate as MPCF, M: 4T1 cell membranes; P: polydopamine; C: calcium phosphate; F: iron dextran) for tumor CDT applications based on ascorbic acid and iron dextran, which is clinically used in the treatment of iron deficiency anemia. The MPCF was fabricated by encapsulating iron dextran nanoparticles within porous calcium phosphate nanoparticle carriers and surface modifying with polydopamine and 4T1 tumor cell membranes. The MPCF can efficiently accumulate at tumor sites and gradually degrade to release the encapsulated iron dextran nanoparticles in response to the acidic tumor microenvironment. Intraperitoneally injected ascorbic acid not only generated hydrogen peroxide at the tumor site, but also synergistically acted with endogenous glutathione to reduce trivalent iron ions in the iron dextran to divalent iron ions, leading to depletion of the excess glutathione at the tumor site and amplification of oxidative stress effects. In addition, polydopamine-mediated photothermal therapy (PTT) can further enhance the CDT effect. In vitro and in vivo experiments demonstrated that the combination therapy of CDT and PTT based on the MPCF exhibited effective tumor inhibition and good biosafety properties. Therefore, the nanoplatforms prepared with the clinical drug iron dextran provide a new idea for the design of nanoprobes of tumor therapy with clinical translational potential.

Nickel-rich ternary cathode material as a novel capping layer to improve lithium iron phosphate electrochemical performance

We use a facile high-temperature solid-phase method to coat a layer of Ni-rich ternary material (LiNi0.8Co0.1Mn0.1O2) on the surface of lithium iron phosphate. This active coating greatly improves the intrinsic conductivity of LiFePO4. Compared to the conventional carbon material cladding, since this cladding layer is electrochemically active, the problem of decreasing the proportion of active material due to the addition of a cladding layer can be avoided to a certain extent. Compared with the samples capped with conventional organic carbon source (151.2 mAh g−1) and inorganic carbon source (155.9 mAh g−1) at 0.2 C, the discharge specific capacity was as high as 165.7 mAh g−1. Capacity retention after 200 cycles is up to 98 %, which is much higher than that of glucose and graphene oxide (GO)-coated samples (95.9 %, 96.6 %). Even when charging and discharging cycles are performed at different multipliers (2C and 10C), the retention rate remains higher than the latter.

Features of the crystal structure and surface of superprotonic conductor caesium hydrogen sulfate phosphate.

The crystal structure of superprotonic conductor caesium hydrogen sulfate phosphate [Cs4(HSO4)3(H2PO4)] have been analyzed using neutron diffraction methods. Additionally, its structure and surface layers have been investigated using atomic force microscopy. From the diffraction data obtained, Fourier syntheses of neutron scattering densities were calculated, and the localization of hydrogen atoms and the parameters of three types of hydrogen bonds in the crystal structure were accurately determined. Correlation of surface characteristics of samples obtained by atomic force microscopy with their crystal structure is shown.

Influence of Phosphate Surface Coating on Performance of Aqueous‐Processed NMC811 Cathodes in 3 Ah Lithium‐Ion Cells

AbstractAqueous processing of state‐of‐the‐art cathode materials for lithium‐ion batteries like LiNi0.8Mn0.1Co0.1O2 (NMC811) has evolved as a more sustainable and cost‐effective alternative to the conventional 1‐methyl‐2‐pyrrolidone‐based process. However, the implementation of aqueous processing is challenging due to the water sensitivity of nickel‐rich layered oxides. This study investigates the influence of a phosphate‐based NMC811 surface coating on the performance of aqueous‐processed NMC811 cathodes in 3 Ah cells. The results show that the cells with phosphate‐coated NMC811 outperform those with uncoated NMC811, i. e., they exhibited higher initial capacity and improved capacity retention during cycling. Post‐mortem characterization techniques reveal that the phosphate coating limits the lithium loss during aqueous cathode manufacturing and further reduces side reactions during cycling, resulting in a smaller increase of cell impedance.

Quasi-in-situ Observation and SKPFM Studies on Phosphate Protective Film and Surface Micro-Galvanic Corrosion in Biological Mg–3Zn–xNd Alloys

Quasi-in-situ Observation and SKPFM Studies on Phosphate Protective Film and Surface Micro-Galvanic Corrosion in Biological Mg–3Zn–xNd Alloys

Selective oxidation of methanol to green oxygenates on vanadium-aluminum phosphate based catalysts

The methanol transformation reaction in the presence of oxygen was carried out in the temperature range of 210–310 ºC, over vanadium catalysts based on vanadium oxide (V2O5) and on vanadium-phosphorus oxide (VPO) calcined at 450 ºC in air. Specifically, the vanadium oxide systems with V2O5 loadings below, above or corresponding to the theoretical monolayer (1–34 wt% of V2O5) were obtained by the impregnation of a mesoporous amorphous aluminum phosphate, AlPO4, calcined at different temperatures (from 350 ºC to 650 ºC) with vanadyl oxalate. Additionally, mechanical mixtures of either VPO or V2O5 with AlPO4 were also employed. Under the experimental conditions employed, with a methanol enriched feed (O2/methanol molar ratio=0.6), formaldehyde and dimethoxymethane were the main products obtained with all the catalysts studied. Vanadyl phosphate (VPO) exhibited slightly lower activity than vanadium oxide, formaldehyde being the main product (SFA ≥ 95%). The conversion of both vanadium oxide and vanadyl phosphate appreciably increased when mixed with the AlPO4, also promoting the formation of dimethoxymethane. The interaction of the vanadium species with the aluminum phosphate surface took place preferentially through the surface Al-OH groups, the vanadium species with less development being the most active in the formation of formaldehyde and dimethoxymethane, per at-g of vanadium.

Speciation studies at the Illite - solution interface: Part 2 – Co-sorption of uranyl and phosphate ions

Although it is well known that clays and phosphate ions (hereafter referred to as “P”) can contribute to the long term uptake of uranium (U) in a variety of geochemical systems, work is still needed to document the surface speciation of U(VI) and P sorbed on relevant clay minerals such as illite. Following on from previous work showing strong sorption of phosphate ligands on the surface of a homoionic Na-illite ([1]), we addressed the (competitive/synergistic) mechanisms of (co)sorption of trace levels of uranyl ions (1–10 µM) and phosphate ligands (100 µM) onto this clay, and the identity of the surface species formed, by in situ spectroscopy monitoring of the clay-solution interface along sorption. We also performed complementary batch sorption experiments and electrophoretic mobility (EM) measurements. Macroscopic data indicated a uranyl sorption dependent on pH, aqueous U concentration and clay-to-solution ratio, a signature of P on the U sorption, and a promotion of P sorption with U concentration. Macroscopic and EM data also suggested mostly reversible mechanisms of P and U co-sorption that confer negative charges on the mineral surface and involve several types of uranyl phosphate surface species and/or surface sites present on the clay edges. FTIR interface spectra confirmed that several types of inner sphere uranyl phosphate surface species formed at acidic pH at the illite-solution interface, as a function of U surface coverage and/or reaction time. An inner-sphere uranyl phosphate surface complex, likely with a U-bridging structure, was formed rapidly on high-affinity surface sites existing in limited quantities on the clay edges. Another U-P surface complex (with a possible P-bridging structure) was progressively formed in increasing amounts with U surface coverage and time on low affinity clay edge sites. Finally, a third U-P surface species having an autunite-like structure (probably a U-P polynuclear surface species) was formed on the illite surface at high U concentration (10 µM). The two later species competed with the existence on the illite surface of inner sphere surface complexes and outer-sphere surface complex of phosphate, which were identified in the absence of U. Information on uranyl surface speciation in the presence of phosphate ligands presented here is novel and provides for the first time in situ spectroscopic evidence of synergistic U-P sorption process leading in the formation of several types of uranyl phosphate sorption species on the surface of illite. These results provide a sound basis for better understanding / prediction of U sorption in the environment, including in clayey formations being considered as long term barriers to radionuclide migration in far field of high level radioactive waste repository.

Preparation and properties of porous calcium phosphate ceramic microspheres modified with magnesium phosphate surface coating for bone defect repair

Most studies have highlighted the critical influence of bioactive metal ions and pore structure on the bone repair performance of calcium phosphate. In this study, porous calcium phosphate ceramic microspheres with different porosities (45 %, 60 %, and 75 %) and pore sizes (20, 40, and 100 μm) were constructed by combining the extrusion-rolling and pore-forming agent methods, and they were then characterized as well as their physicochemical and biological properties. On this basis, the screened porous calcium phosphate microspheres were further coated with magnesium phosphate to improve the performance of osteogenesis and angiogenesis. The results demonstrated that pore size and porosity promoted the degradation properties. However, excessive pore size and porosity also resulted in a significant decline in the mechanical performance and biological properties of the microspheres. Successful magnesium phosphate coating of ceramic microspheres did not adversely affect their physicochemical performance and allowed stable release of magnesium ions, which further enhanced the biological properties of porous ceramic microspheres, such as cell proliferation, osteogenic differentiation, and angiogenic properties. This study presents an efficient and practical processing method to further enhance the properties and expand the applications of calcium phosphate materials.

Speciation studies at the Illite - solution interface: Part 1 – Sorption of phosphate ions

Although phosphate ion (hereafter “P”) sorption is known to influence clay surface reactivity and trace metal behavior in the environment, there is still a lack of in situ spectroscopic evidence on the identity of phosphate sorption species formed at the interface between solution and clays with a 2:1 layered structure (2 silica tetrahedral: 1 octahedral layers), which are ubiquitous in soils and clay formations. We studied the surface speciation of phosphate ions by in situ spectroscopic monitoring along P sorption at the interface between a solution and a homoionic Na-illite, as a function of time or aqueous phosphate concentration (20–250 µM) leading to low/moderate P surface coverage. We also combined them with batch sorption experiments and electrophoretic mobility (EM) measurements. Macroscopic data indicated that the percentage of P sorption depends on pH, aqueous phosphate concentration, and the clay/solution ratio of the experiment, i.e., the coverage of the clay surface by P, with a maximal sorption capacity of the clay equal to ca. 6 µmol.g−1 at pH 4. Macroscopic and EM data further suggest that P sorption mechanisms onto illite confer negative charges on the surface and involve several sorption species and/or surface sites present on the clay edges. In situ FTIR spectra showed that, at acidic pH, three types of phosphate surface species exist at the illite-solution interface: an outer-sphere surface complex (OSSC) of phosphate (ΞSOH2+…H2PO4-, with S referring to a sorption site on the clay), an inner-sphere surface complex (ISSC) of phosphate, probably a monodentate binuclear surface complex ((ΞSO)2PO2) formed by surface ligand exchange with high-affinity aluminol sites and, to a lesser extent, low-affinity sites on the clay edges, and, in limited amounts, an Al-phosphate surface precipitate. Phosphate ion sorption occurs through the initial formation of the OSSC of phosphate, which dominates phosphate surface speciation at short reaction times and low P concentrations and transforms over time into the ISSC of phosphate. This study presents the first published in situ surface speciation of phosphate ions sorbed at the interface between a solution and an illite. The evidence of a strong sorption of phosphate ions at this clay surface provides new and sound knowledge to better understand the environmental fate of phosphate ions and trace metals, particularly in agricultural soil - groundwater continua or in clay host rocks considered for high-level radioactive waste disposal.

Effect of Low-Level Laser Irradiation (810 nm) on the Proliferation and Differentiation of Osteoblast-Like Cells Cultured on SLA Titanium Discs Exposed to a Peri-implantitis Environment.

Introduction: Elimination of inflammation and re-osseointegration are the major objectives of peri-implantitis therapy. Existing data, however, do not support any decontamination approach. Thus, the present in vitro study aims to assess whether the air-debriding decontamination method with erythritol powder restores the biocompatibility of infected titanium discs and to investigate the potent biomodulatory ability of diode laser (810 nm) irradiation to promote cell proliferation and differentiation of premature osteoblast-like cells (MG63) towards osteocytes. Methods: The experimental groups consisted of cells seeded on titanium discs exposed or not in a peri-implantitis environment with or without biomodulation. Infected discs were cleaned with airflow with erythritol powder. Cell cultures seeded on tricalcium phosphate (TCP) surfaces with or without biomodulation with a laser (810 nm) were used as controls. The study evaluated cell viability, proliferation, adhesion (SEM) at 24, 48 and 72 hours, and surface roughness changes (profilometry), as well as the effects of low-level laser therapy (LLLT) on ALP, OSC, TGF-b1, Runx2, and BMP-7 expression in MG63 cells' genetic profile on days 7, 14, and 21. Results: The MTT assay as well as the FDA/PI method revealed that cell proliferation did not show significant differences between sterile and decontaminated discs at any timepoint. SEM photographs on day 7 showed that osteoblast-like cells adhered to both sterile and disinfected surfaces, while surface roughness did not change based on amplitude parameters. The combination of airflow and LLLT revealed a biomodulated effect on the differentiation of osteoblast-like cells with regard to the impact of laser irradiation on the genetic profile of the MG63 cells. Conclusion: In all groups tested, osteoblast-like cells were able to colonize, proliferate, and differentiate, suggesting a restoration of biocompatibility of infected discs using airflow. Furthermore, photomodulation may promote the differentiation of osteoblast-like cells cultured on both sterile and disinfected titanium surfaces.

Surface stabilized Ni-rich LiNi0.9Co0.08Al0.02O2 cathode materials via surface modification with GdPO4 for lithium-ion batteries

Ni-rich LiNixCoyAl1-x-yO2 (NCA) with high energy density and relatively low cost is a promising candidate. However, interfacial instability and severe kinetic hindrance lead to severe property fading and serious safety concerns during the prolonged Li+ intercalation. Herein, we introduce an effective inorganic coating strategy for gadolinium phosphate (GdPO4) surface modified NCA cathode material by a sample wet-chemical method, which enhance the layered structural stability, lower the lithium migration barrier. As a result, superior rate capacity and stable capacity retention for NCA are exhibited after GdPO4 coating. Especially for 3 wt% GdPO4 coated sample, the first discharge capacity is 102.7 mA h g−1 at 5C, as well as capacity retention of 85% after 100 cycles. The improved electrochemical performance turns out to be uniform and thin coating layer by transmission electron microscope, the decreased voltage polarization by cyclic voltammetry, as well as the resistance changes between the cathode and solid electrolyte by electrochemical impedance spectroscopy. Taking all these findings into account, it is evident that GdPO4-coated Ni-rich cathode material can be utilized in advanced lithium-ion batteries.

Determination of stress waves and their effect on the damage extension induced by surface defects of KDP crystals under intense laser irradiation

The residual crack defects on the surface of potassium dihydrogen phosphate (KDP) crystals are the bottleneck that limits the improvement of laser damage resistance in the application of high-power laser devices. The multiple stress waves introduced by these residual surface lateral cracks on crystals under laser irradiation are the main inducement for damage extension and reduction of laser damage resistance. However, the coupling of these stress waves complicates their propagation in the crystal, and the interaction mechanism between each stress wave and laser damage has not been quantitatively characterized. Herein, a laser damage dynamic model for surface lateral cracks is constructed to reproduce the dynamic behaviors of the evolution of micro-defects to sub-millimeter damage pits under laser irradiation. Combined with the time-resolved pump and probe technique, the distribution of stress waves induced by lateral cracks was detected in situ to determine the type of stress waves. Then, the initiation and extension of laser damage were analyzed quantitatively to establish the correlations between different stress waves and damage extension. It is found that the longitudinal, shear, and Rayleigh waves induced by lateral cracks lead to large crush zones on the surface of KDP crystals, as well as butterfly-like damage sites accompanied by a large number of cracks at the bottom in the longitudinal section. The scale of the damage site can reach up to approximately 150 µm for lateral crack defects with large surface widths. This study ultimately reveals the physical mechanism of damage evolution induced by lateral cracks, providing effective guidance for developing control standards of surface crack defects during optical ultra-precision machining processes. This is of great significance for the improvement of laser damage resistance of KDP crystals in high-power laser systems.

Two-dimensional solid-state NMR spectroscopy investigations of surface precipitation of phosphate onto calcite

The interaction of phosphate with typical soil minerals is important for understanding P cycling in natural and agricultural systems. We investigated the mechanisms of kinetics of phosphate uptake onto calcite using solid-state NMR spectroscopy. At a low phosphate concentration of 0.5 mM, the 31P single-pulse solid-state NMR peak revealed the formation of amorphous calcium phosphate (ACP) within the initial 30 min, which transformed to carbonated hydroxyapatite (CHAP) after 12 d. At a high phosphate concentration (5 mM), the results showed transformation from ACP to OCP, later to brushite, and eventually to CHAP. The formation of brushite is further supported by 31P{1H} heteronuclear correlation (HETCOR) spectra via a correlation of δP–31 = 1.7 ppm and the 1H peak at δH–1 = 6.4 ppm, which denotes the structure water of brushite. Furthermore, 13C NMR directly revealed both A-type and B-type CHAP. Generally, this work provides a detailed understanding of the aging effect on the phase transition scale of phosphate surface precipitation onto calcite in soil environments.

Cycling performance of silicon‐carbon composite anodes enhanced through phosphate surface treatment

AbstractSilicon (Si)‐based anodes have long been viewed as the next promising solution to improve the performance of modern lithium‐ion batteries. However, the poor cycling stability of Si‐based anodes impedes their application and calls for solutions for further improvements. In the present work, the incorporation of phosphate groups on the surface of an amorphous Si‐carbon composite (a‐Si/C) has been achieved by a hydrothermal reaction using phosphoric acid and sodium dihydrogen phosphate at pH = 2. Different levels of the surface P‐doping have been realized using reaction times (2, 4, and 8 h) at two different phosphate concentrations. The presence of phosphate groups on the particle's surface has been confirmed by energy‐dispersive X‐ray, infrared, and Raman spectroscopy. The cycling stability of the P‐treated a‐Si/C composites has been significantly improved when using lithium bis(trifluoromethanesulfonyl)imide as a salt in ether‐based solvents mixture compared to a conventional electrolyte for Si‐based anodes (LiPF6 in carbonate‐based solvents). Coulombic efficiencies as high as 99% have been reached after five charge/discharge cycles for almost all phosphate‐treated materials. The 4 h P‐treated a‐Si/C composite electrode exhibits the best reversible capacity of 1598 mAh g−1 after 200 cycles demonstrated in half‐cells using an ether‐based electrolyte.

In vitro cellular biocompatibility and in vivo degradation behavior of calcium phosphate-coated ZK60 magnesium alloy

Calcium phosphate (Ca-P) surface coating is a simple but effective way to enhance both corrosion resistance and biocompatibility of ZK60 magnesium alloy. However, cell compatibility on different Ca-P layers coated on ZK60 alloy has seldom been investigated. In this study, the effects of type, morphology and corrosion protection of several Ca-P coatings formed at pH 6.5, 7.8 and 10.2 on cell behavior were examined by using an osteoblastic cell line MC3T3-E1. Furthermore, in vivo behavior in rabbits of the alloy coated with the optimum Ca-P layer was also studied. It was found that the surface factors governed the cell morphology and density. The coating morphology plays a dominant role in these surface factors. The sample coated at pH 7.8 showed the best cellular biocompatibility, suggesting that the hydroxyapatite (HAp) layer formed at pH 7.8 was the optimum coating. In rabbits, this optimum coating enhanced remarkably the corrosion resistance of the alloy. During implantation, the outermost crystals of the HAp coating were shortened and thinned due to the dissolution of HAp caused by the body fluid of the rabbits. It is indicated that ZK60 alloy coated at pH 7.8 can be applied as a biodegradable implant.