Interconnected Morphology Research Articles

Investigation on preparation porous titanium through calciothermic reduction of porous TiO precursors

A route is present for preparing porous titanium scaffolds with open and interconnected pore morphology through calcium thermal in-situ reduction of TiO precursor. Titanium and dioxide titanium powders, with ammonium carbonate as the space holder, were used to prepare porous precursor whose main phase is TiO by a sintering process. Then calcium vapor was conduced to reduce the precursor and CaO was removed by leaching to obtain porous titanium structures. The morphology, pore structure, phase analysis of porous titanium precursor and porous titanium scaffolds were investigated by means of XRD, SEM and EDS. The porosity was observed by Archimedes method. By this route, the porous titanium with multi-gradient pore sizes ranging from a few microns to several hundred microns was formed. The porous titanium is of multi-gradient pore size distribution of 100 μm bigger, 10 μm∼100 μm and 10 μm smaller. The micro-pores on the pore walls increases connectivity between the macro-pores throughout the porous titanium interior. The porous titanium obtained by this method has a porosity of 50–65% and a titanium content more than 99%.

Luminescent Porous Silicon Filled with Nanoscopic Magnetic Structures – Assessment of the Optical and Magnetic Properties

Luminescent porous silicon which is denoted as microporous silicon offers a structure size of a few nanometers. It is filled with magnetic metals resulting in a composite system with specific optical and magnetic properties. The morphology of microporous silicon offers a branched network of pores. The luminescence which is observed in the red-orange region due to the small structure size is influenced by the metal filling. The magnetic response of the samples is related to the interconnected pores and differs significantly to mesoporous silicon filled with magnetic nanostructures of similar size.The luminescent porous silicon is etched in aqueous hydrofluoric acid solution by applying a current density of 10 mA/cm2 for 20 min resulting in a porous layer of about 0.8 µm thickness. The metal filling of microporous silicon is a challenging procedure which is carried out under cathodic conditions by pulsed electrodeposition. As electrolytes adequate metal salt solutions are used. The deposited nanosized metal structures are of the same interconnected sponge-like morphology as the template material.Mesoporous silicon offers oriented pores whereas the diameter is in the range of 50 nm [1]. Also in this case the metal nanoparticles are electrodeposited within the matrix material.The magnetic properties of the different systems rely on the morphology of the template material and the size and geometry of the incorporated metal deposits.The magnetic response offers a significant difference between filled luminescent and mesoporous silicon samples. Luminescent metal filled samples show strong magnetic anisotropy between the magnetization parallel and perpendicular to the surface. For these specimens also significant differences of the anisotropy can be observed depending on the kind of deposited metal, e.g. Ni or Co. These differences are not so distinctive in the case of mesoporous metal filled silicon because of weak magnetic interactions between the metal nanoparticles.Due to the merged optical and magnetic properties in the case of microporous silicon the nanocomposite could be promising for integrated magneto-optic devices.[1] P. Granitzer, K. Rumpf, Semiconductor Science and Technology 31, 4004, 2016.

The synergistic reinforcing effects of halloysite nanotube particles and polyolefin elastomer-grafted-maleic anhydride compatibilizer on melt and solid viscoelastic properties of polylactic acid/ polyolefin elastomer blends

The effect of halloysite nanotube (HNTs) particles and polyolefin elastomer-graft-maleic anhydride (POE-g-MA) in the polylactic acid (PLA) and polyolefin elastomer (POE) blend with a constant weight percentage composition have been studied using the scanning electron microscopy, rheometry, dynamic mechanical thermal analysis (DMTA) as well as the thermogravimetric testing. Through these, it was found that the simultaneous presence of POE-g-MA and HNT significantly improves the melt and solid viscoelastic properties and thermal stability of PLA/POE. This improvement is attributed to the increased interactions and improved interfacial adhesion between the present components. The microscopic images of PLA/POE-g-MA/POE (80/8/12) blend containing 4 wt% HNT showed a microstructure similar to the interconnected morphology due to the enhanced compatibility and better dispersion of nanoparticles. The rheological behavior was significantly changed for the PLA/POE blend containing POE-g-MA and 4 wt% HNT. This dramatic increase in the rheological properties was consistent with the morphological results. Only one glass transition temperature was observed in the DMTA plot of PLA/POE-g-MA/POE blend, which was a sign of a homogeneous, fully compatible system. In addition, a very strong reinforcing effect of HNT particles was observed in the presence of POE-g-MA for the nanocomposites. Finally, the thermogravimetric analysis showed a completely different trend for thermal degradation of PLA/POE-g-MA/POE nanocomposite containing 4 wt% HNT, which could be an indication of microstructural development.

Free-standing 3D network-like cathode based on biomass-derived N-doped carbon/graphene/g-C3N4 hybrid ultrathin sheets as sulfur host for high-rate Li-S battery

Abstract Derived from low-cost biomass chitin with hierarchical N-involving molecular structures, a novel renewable N-doping carbonaceous host material (denoted as C-NC) for S cathode in Li-S batteries with 3D network-like structures was fabricated via a facile dissolution and carbonization approach. When incorporated with a small amount of graphene (GN) and g-C3N4, the final products of C-NC/GN/g-C3N4 hybrids maintain the 3D interconnected network-like morphology assembled by 2D ultrathin graphene-like sheets. Meanwhile, the hybrids synergize the advantages of the graphene with high conductivity to facilitate fast electron transfer, the g-C3N4 with efficient chemical absorptivity for intermediate polysulfides to inhibit the unfavorable dissolution, as well as the 3D network frameworks of C-NC with high surface area and macro/mesoporous features to offer rapid ion diffusion channels and adequate electrolyte infiltration and mitigate the structural changes of S cathode during cycling. When loading with elemental S, the fabricated S@C-NC/GN/g-C3N4 cathode shows superior high-rate capability and remarkable cycling performance, which maintains a high reversible capacity of ∼1130 mA h g−1 after 500 consecutive electrochemical cycles. This renewable biomass-based cathode construction strategy offers a low-cost promising approach to design high-rate and ultralong-lifespan Li-S batteries.

Development of Polymeric Nanocomposite (Xyloglucan-co-Methacrylic Acid/Hydroxyapatite/SiO2) Scaffold for Bone Tissue Engineering Applications—In-Vitro Antibacterial, Cytotoxicity and Cell Culture Evaluation

Advancement and innovation in bone regeneration, specifically polymeric composite scaffolds, are of high significance for the treatment of bone defects. Xyloglucan (XG) is a polysaccharide biopolymer having a wide variety of regenerative tissue therapeutic applications due to its biocompatibility, in-vitro degradation and cytocompatibility. Current research is focused on the fabrication of polymeric bioactive scaffolds by freeze drying method for nanocomposite materials. The nanocomposite materials have been synthesized from free radical polymerization using n-SiO2 and n-HAp XG and Methacrylic acid (MAAc). Functional group analysis, crystallinity and surface morphology were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) techniques, respectively. These bioactive polymeric scaffolds presented interconnected and well-organized porous morphology, controlled precisely by substantial ratios of n-SiO2. The swelling analysis was also performed in different media at varying temperatures (27, 37 and 47 °C) and the mechanical behavior of the dried scaffolds is also investigated. Antibacterial activities of these scaffolds were conducted against pathogenic gram-positive and gram-negative bacteria. Besides, the biological behavior of these scaffolds was evaluated by the Neutral Red dye assay against the MC3T3-E1 cell line. The scaffolds showed interesting properties for bone tissue engineering, including porosity with substantial mechanical strength, biodegradability, biocompatibility and cytocompatibility behavior. The reported polymeric bioactive scaffolds can be aspirant biomaterials for bone tissue engineering to regenerate defecated bone.

Syntheses and characterizations of GO/Mn3O4 nanocomposite film electrode materials for supercapacitor applications

We have, in this study; used simple, in-expensive and environmentally-friendly successive ionic layer adsorption and reactions (SILAR) deposition procedure to successfully grow GO/Mn3O4 thin film electrode materials. The deposited films were examined for their surface morphology using scanning electron microscopy (SEM) while its morphology and structure was confirmed using transmission electron microscopy (TEM) and selected area electron diffractometry (SAED) respectively. X-ray diffraction (XRD) was used to study their structural properties while their supercapacitive studies were obtained using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS) techniques. All deposited films were scanned in 1 M solution of Na2SO4 electrolyte. The SEM images of the deposited films revealed highly porous interconnected morphology with Mn3O4 densely dispersed among graphene oxide (GO). Individual peaks of Mn3O4 and GO compounds indicating uniform spread of Mn3O4 inside the porous matrix of GO were observed from the XRD. Mn3O4 nanograins well-dispersed on the surface were further confirmed through the TEM images while bright concentric rings confirming the polycrystalline nature of the films were observed from SAED images. The film deposited at 40 cycles yielded the maximum specific capacitance of 532.54 Fg−1at 5 mVs−1 scan rate. The results of the electrochemical studies show that the GO/Mn3O4 composite films synthesized by SILAR could be a promising material for supercapacitors.

Biobased pH-responsive and self-healing hydrogels prepared from O-carboxymethyl chitosan and a 3-dimensional dynamer as cartilage engineering scaffold

Novel dynamic hydrogels were prepared from O-carboxymethyl chitosan (CMCS) and a water soluble dynamer Dy via crosslinking by imine bond formation using an environmentally friendly method. Dy was synthesized by reaction of Benzene-1,3,5-tricarbaldehyde with Jeffamine. The resulting soft hydrogels exhibit a porous and interconnected morphology, storage modulus up to 1400 Pa, and excellent pH-sensitive swelling properties. The swelling ratio is relatively low at acidic pH due to electrostatic attraction, and becomes exceptionally high up to 7000 % at pH 8 due to electrostatic repulsion. Moreover, hydrogels present outstanding self-healing properties as evidenced by closure of split pieces and rheological measurements. This study opens up a new horizon in the preparation of dynamic hydrogels with great potential for applications in drug delivery, wound dressing, and in particular in tissue engineering as the hydrogels present excellent cytocompatibility.

Enhancement of solvent uptake in porous PVDF nanofibers derived by a water-mediated electrospinning technique

The effect of a N,N-dimethylformamide (DMF)/acetone solvent system (3:7, 4:6, 5:5, 6:4, 7:3) and spinning medium (air and water) on the membrane morphology and the structure-property relationship were investigated. A facile method was optimized to generate a porous, polymer-fiber membrane via the combinative effect of electrospinning and thermally inducing phase separation of the DMF/acetone (4:6) solvent system in a water medium. The attenuated total reflection (ATR) - Fourier transform infrared (FTIR) results showed an increased β-phase compared to the pristine poly(vinylidene fluoride) (PVDF). The XRD and DSC results further confirmed that the co-existing α- and β-phases in the pristine PVDF were converted into a unique β-phase in the electrospun membranes. In addition, the solvent uptake percentage of the DMF/acetone (4:6) solvent system in a water medium (540) is much greater than that in an air medium (320), and over two times better than that of commercial polyethylene (PE) membranes (190). Similarly, the discharge capacity of the PVDF membrane separator prepared with the DMF/acetone (4:6) solvent system in a water medium is higher than that of the air medium. This enhancement of solvent uptake might be due to the interconnected porous morphology present in the water medium.

In situ constructing lithiophilic NiFx nanosheets on Ni foam current collector for stable lithium metal anode via a succinct fluorination strategy

Metallic lithium is considered as the optimal anode material for the high-energy–density rechargeable lithium-based battery. However, the commercial application of Li metal anode is plagued by uncontrollable dendrites growth and unstable SEI layer derived from the nonuniform nucleation and undesired deposition process. Herein, a hybrid 3D porous Ni foam (NF) current collector decorated by nanostructured lithiophilic layer of interconnected NiFx nanosheets is firstly synthesized by a convenient one-step fluorination strategy. Benefiting from superior lithiophilicity, the NiFx nanosheets can successfully decrease the Li nucleation barrier and act as uniformly distributed nucleation sites for inducing the homogeneous Li deposition. In addition, the interconnected morphology of the NiFx nanosheets and the 3D porous structure of the NF effectively reduce the local current density of the electrode and thus alleviate the dendrites formation. Moreover, a LiF-enriched SEI layer in situ generated from the electrochemical reaction also facilitates the smooth Li plating. As a result, this 3D hybrid NiFx@NF current collector demonstrates dendrite-suppressed Li deposition morphology and excellent stripping/plating reversibility, presenting significantly enhanced Coulombic efficiency of ~ 98% over 450 cycles at 1 mA cm−2. Remarkably, symmetric cell with Li@NiFx@NF anode achieves a prolonged cycling lifespan over 1300 h together with a low overpotential of ~ 20 mV at 1 mA cm−2 under the cycling capacity of 1 mAh cm−2. Furthermore, excellent cycling performance and rate capability of the Li@NiFx@NF anode are also realized in full cells when coupled with LiFePO4 and Li4Ti5O12 cathodes. Our work not only provides an expeditious fluorination strategy to construct 3D fluorinated compound but also illustrates the superiority of synergetic design of lithiophilic sites plus LiF-enriched SEI layer for the current collector of Li metal anode.

Novel CuCo2O4 Composite Spinel with a Meso-Macroporous Nanosheet Structure for Sulfate Radical Formation and Benzophenone-4 Degradation: Interface Reaction, Degradation Pathway, and DFT Calculation.

A series of CuCo2O4 composite spinels with an interconnected meso-macroporous nanosheet morphology were synthesized using the hydrothermal method and subsequent calcination treatment to activate peroxymonosulfate (PMS) for benzophenone-4 (BP-4) degradation. As-prepared CuCo2O4 composite spinels, especially CuCo-H3 prepared by adding cetyltrimethylammonium bromide, showed superior reactivity for PMS activation. In a typical reaction, BP-4 (10.0 mg/L) was almost completely degraded in 15 min by the activation of PMS (200.0 mg/L) using CuCo-H3 (100.0 mg/L), with only 9.2 μg/L cobalt leaching detected. Even after being used six times, the performance was not influenced by the lower leaching of ions and surface-absorbed intermediates. The possible interface mechanism of PMS activation by CuCo-H3 was proposed, wherein a unique interconnected meso-macroporous nanosheet structure, strong interactions between copper and cobalt, and cycling of Co(II)/Co(III) and Cu(I)/Cu(II) effectively facilitated PMS activation to generate SO4•- and •OH, which contributed to BP-4 degradation. Furthermore, combined with intermediates detected by liquid chromatography quadrupole time-of-flight mass spectrometry and density functional theory calculation results, the degradation pathway of BP-4 involving hydroxylation and C-C bond cleavage was proposed.

Long OPA1 isoforms mediate a membrane potential‐dependent threshold for mitochondrial fusion in AC16 cardiomyocytes

The bioenergetic function of mitochondria is linked to its organellar structural dynamics by optic atrophy‐1 (OPA1), a nuclear‐encoded protein that mediates fusion of the mitochondrial inner membrane. OPA1‐mediated inner membrane fusion is dependent on the transmembrane potential across the mitochondrial inner membrane (Δψm): long (L‐OPA1) isoforms accomplish fusion for an interconnected reticular morphology when Δψm is intact. Upon loss of Δψm, L‐OPA1 is cleaved by the OMA1 metalloprotease, causing accumulation of short S‐OPA1 and collapse of mitochondrial fusion to a fragmented morphology. We examined Δψm‐sensitive mitochondrial fusion in human AC16 cardiomyocytes treated with carbonyl cyanide m‐chlorophenyl hydrazone (CCCP), an uncoupler of Δψm. Upon increasing titration with CCCP, mitochondrial fusion collapses at [CCCP] > 2 μM, as determined using blinded ImageJ quantification of mitochondrial morphology. Similarly, OPA1 Western blotting revealed that AC16s show a significant loss of fusion‐active L‐OPA1 at [CCCP] > 2 μM. Taken together, these findings indicate that L‐OPA1 maintains mitochondrial fusion, but that OMA1 is activated at [CCCP] > 2 μM, causing L‐OPA1 cleavage and collapse of mitochondrial fusion. Experiments in progress are examining OMA1 activation at this Δψm breakpoint, as well as impact of altered OPA1 and OMA1 expression.Support or Funding InformationNIGMS 5SC3GM116669 (to R.G.)NIGMS 1SC3GM132053 (to M.K.)UTRGV Presidential Graduate Research Assistantship (to P. D.)

Biodegradable porous polylactic acid film as a separator for supercapacitors

AbstractA porous polylactic acid (PLA) film was investigated as a separator for supercapacitors (SCs) and compared with commercial separators, for example, NKK‐MPF30AC and Celgard 2400. The porous PLA film was fabricated via a facile phase inversion method, and the cross‐sectional scanning electron microscope images of the PLA separator film exhibited highly porous interconnected morphology for ion diffusion. The surface modification of separators was performed by radio frequency (RF) air plasma to improve wettability. The plasma modification enhanced the water uptake and swelling properties of the separators and decreased the water contact angles of PLA and Celgard 2400 films. The mechanical and dielectric properties of separators were also studied. The ionic conductivities of RF‐PLA in 1 M H2SO4 and 1 M Na2SO4 were found to be 1.1 × 10−1 S/cm and 0.6 × 10−2 S/cm at room temperature, respectively. The electrochemical impedance spectroscopy of the RF‐PLA SCs showed the lowest solution resistance and internal resistance.

Green synthesis of ZnO nanoparticles decorated on polyindole functionalized-MCNTs and used as anode material for enzymatic biofuel cell applications

Presently, one of the most important aspects for the development of enzymatic biofuel cells (EBFCs) is to synthesize the novel electrode materials that possess high current density, low open-circuit voltage (OCV) and long-term stability. To achieve the above attributes, lots of new strategies are being used by the researchers for the development of advanced materials. Nowadays, nanomaterials and nanocomposites are the promising material that has been utilized as effective electrode material in solar cells, supercapacitors and biofuel cells application. Herein, we account for a novel electrocatalyst as electrode material that comprised ZnO nanoparticles decorated on the surface of polyindole (PIn)-multi-walled carbon nanotube (MWCNT), for the immobilization of glucose oxidase (GOx) enzyme and mediator (Ferritin). The PIn-MWCNT scaffold is prepared via in situ chemical oxidative polymerization of indole on the surface of MWCNT and assessed by myriad techniques. The micrograph of scanning electron microscopy (SEM) designated the interconnected morphology of MWCNTs in the polymer matrix. X-ray diffraction spectroscopy (XRD) and Fourier transform infrared spectroscopy (FTIR), confirm the crystallinity and different functional groups available in the synthesized material, respectively. The electrochemical assessment demonstrates that the ZnO/PIn-MWCNT/Frt/GOx nanobiocatalyst exhibits much higher electrocatalytic activity towards the oxidation of glucose with a maximum current density of 4.9 mA cm−2 by consuming 50 mM glucose concentration in phosphate buffer saline (PBS) (pH 7.4) as the testing solution by applying 100 mVs−1 scan rates. The outcomes reflect that the as-prepared ZnO/PIn-MWCNTs/Frt/GOx biocomposite is a promising bioanode for the development of EBFCs.

The Use of Conductive Polymers Embedded Macro Porous Pei and Ionic Liquid Form of Pei Cryogels for Potential Conductometric Sensor Application to CO2

Polyethyleneimine (PEI) cryogels with interconnected superporous morphology were synthesized via the cryopolymerization technique. Then, conductive polymers, poly(Aniline) (PANi), poly(Pyrrole) (PPy), and poly(Thiophene) (PTh) were prepared within these PEI cryogels. Then, the conductive polymer embedding PEI composites’ characterization was carried morphologically using scanning electron microscope (SEM) by means of Fourier Transform Infrared Radiation (FT-IR) spectrometer, and by means of electrical conductivity measurements using an electrometer. Among all the prepared cryogel conductive polymer composites, the highest value in terms of conductivity was determined for PEI/PANi cryogel composites with 4.80 × 10−3 S.cm−1. Afterward, to prepare polymeric ionic liquid (PIL) forms of PEI and PEI/PANi composites. To assess the effect of anions on the conductivities of the prepared composites, PEI-based cryogels were anion ex-changed after protonation with HCl by treatment of aqueous solutions of sodium dicyanamide (Na+[N(CN)2]−), ammonium hexafluorophosphate (NH4+[PF6]−), sodium tetrafluoroborate (Na+[BF4]−), and potassium thiocyanate (K+[SCN]−), separately. Furthermore, PEI-based cryogel composites and their PIL forms were tested as a sensor for CO2 gas. The higher conductivity changes were observed on bare PEI cryogel and PEI+[BF4]− PIL cryogels with 1000-fold decrease on conductivity upon 240 min CO2 exposure. The sensitivity and recovery percent of bare PEI and PEI+[BF4]− PIL cryogels were shown almost the same with a two-fold decrease in the presence of 0.009 mole of CO2 gas, and approximately 30% recovery after the fifth consecutive reuse.

Insights into interfacial speciation and deposition morphology evolution at Mg-electrolyte interfaces under practical conditions

Abstract Rechargeable magnesium (Mg) battery technologies show the promise of low cost, less safety concerns and relatively higher energy density. Interrogating the critical issues on the Mg stripping/plating performance as well as the Mg metal anode-electrolyte interfacial chemistry is one great importance under the practical areal capacity and rate conditions. In this work, we systematically investigate the electrochemistry of Mg stripping/plating processes within four distinctive Mg-ion electrolytes and the Mg anode-electrolyte interfacial chemistry under practical conditions. Electrochemical results show that the cycle life of Mg//Cu asymmetric cells using these above electrolytes is significantly shortened (less than 10 cycles) when tested at a practical areal capacity of 10 mAh cm−2. Further optical and electron microscopic analyses reveal that the gradual growth of the Mg deposits is susceptible to detachment from the copper substrate, where the initial nucleation process might occur. In spite of showing an interconnected particle-like morphology, the Mg deposits could easily penetrate the porous separator, leading to cell failure. The co-deposition of metallic Al is revealed from surface region to bulk, while the Cl-containing species exist in the near surface of Mg deposits. Our work not only highlights the critical impacts of areal capacity on the performances of Mg stripping/plating process, but calls for further efforts to eliminating the safety concerns of Mg anode under practical conditions.

Free-standing interconnected carbon nanofiber electrodes: new structural designs for supercapacitor application

This work aims to develop and characterize a new design of free-standing interconnected carbon nanofiber electrodes for supercapacitor application. The fibers are obtained via carbonization of three components of electrospun nanofiber mats based on a polyacrylonitrile polymer (as a carbon backbone precursor), polyvinylalcohol (as a sacrificial copolymer), and 0–1.0 wt% multi-walled carbon nanotubes. Carbonizing these ternary composites results in fibers with about twice as large in surface area and one order of magnitude higher in electrical conductivity than those obtained by the carbonization of neat polyacrylonitrile and/or binary polyacrylonitrile-0–1.0 wt% carbon nanotube mats. The carbonized polyacrylonitrile-polyvinylalcohol-0.3 wt% carbon nanotube mat reveals the highest surface area and electrical conductivity and best capacitive performance. It exhibits energy and power densities of 27.8 Wh kg−1 and 110.59 kW kg−1, respectively, and cyclic stability of 95% after 2000 charge–discharge cycles at a charging current of 1.0 Ag−1. The nanotubes’ alignment along the fiber’s axis, the formation of fiber–fiber interconnected morphology with more mesopore pollution, and changes in the graphitization degree and defect features of fiber crystallites are the reasons for the observed increase in the electrical conductivity, surface area, and capacitive performance of the carbon fibers. Therefore, the new design represents a potential free-standing carbon nanofiber electrode for future electrochemical double layer capacitor (EDLC) device fabrication.

Poly(l-lactic acid) (PLLA)/MgSO4·7H2O Composite Coating on Magnesium Substrates for Corrosion Protection and Cytocompatibility Promotion.

Magnesium (Mg) and its alloys show excellent potential as orthopedic implantable materials, with their in vivo degraded Mg ions (Mg2+) known to promote the growth of new bone. However, the swift corrosion process during implantation has greatly hindered its clinical applications. A method to counter the high rate of corrosion is to coat Mg substrates on surfaces with a thin layer of biodegradable polymer. Although such a coating reduces the long-term corrosion rate, it also prevents the short-term release of bone-simulating Mg2+ after orthopedic operations. To balance these contradicting short- and long-term characteristics, we present a polymer-inorganic composite coating on pure Mg substrates that enables Mg-based implants to achieve controllable release of Mg2+ and high corrosion resistance simultaneously. The coatings were fabricated by adding an appropriate amount of inorganic magnesium sulfate heptahydrate (MgSO4·7H2O) salt particles into a biodegradable poly(l-lactic acid) (PLLA) polymer matrix, such that they can percolate inside to form an interconnected morphology during the phase separation between Mg salt and PLLA polymers as solvent evaporates during the drying process, resulting in the formation of an organic-inorganic composite coating. The in vitro corrosion tests indicated that the composite coatings with lower Mg salt loading had the best degradation behavior, resulting in controllable release of Mg2+ and alkaline shift. Cytocompatibility of bare and coated Mg were investigated via MC3T3-E1 preosteoblasts through MTT assay and LIVE/DEAD imaging, along with the observation of cell distribution and adhesion behaviors. The results further demonstrated that the incorporation of a suitable amount of Mg salt particles could further improve the cytocompatibility as compared to the pristine PLLA coating. We believe such fabricated organic-inorganic composite coatings could have great potential for application on Mg substrates to obtain Mg-based biomaterials with higher practical value in clinical treatments.

Morphology-optimized interconnected Ni3S2 nanosheets coupled with Ni(OH)2 nanoparticles for enhanced hydrogen evolution reaction

Hydrogen evolution reaction (HER) performance of Ni3S2 electrocatalyst is associated with different morphologies and chemical compositions. In this work, nanosheets, nanorods and dendrite-like structure of Ni3S2 are synthesized and investigated as HER catalysts. Ni3S2 with interconnected nanosheets morphology exhibits the largest electrochemical active surface area, and thereby the lowest overpotential (288 mV vs. RHE) compared with Ni3S2 nanorods (314 mV vs. RHE) and dendrite-like Ni3S2 (303 mV vs. RHE) morphologies. Based on this, Ni(OH)2 species are further grown on the surface of nanosheets Ni3S2 and thus interconnected Ni3S2@Ni(OH)2 nanosheets have been obtained, demonstrating improved HER performance with decreased overpotential (237 mV vs. RHE) and superior stability. These results suggest that (i) the robust nanosheet structure of Ni3S2 can provide abundant space for contacting with electrolyte, which facilitates the mass transfer; and (ii) the formation of Ni3S2@Ni(OH)2 heterostructure is beneficial for water dissociation in HER process, which brings about accelerated HER kinetics.

3D network of V2O5 for flexible symmetric supercapacitor

The obstacles, faced by flexible lithium-ion batteries (LIB) for its unambiguous synthesis procedure and low power densities for practical applications escalate the position of flexible supercapacitors (SCs) as a new standalone performer in modern energy storage devices. Additionally, some admirable features like supremacy over energy density, cyclic stability and fast response make SCs a vital aspirant among the energy storage devices. Eying on those advantages of SCs, in this work layered oxide V2O5 3D array has been grown on carbon fabric. The prepared electrode exhibits a specific capacitance of 1098 F/g at a scan rate of 5 mV/s in 0.5 M K2SO4 electrolyte at three electrode configurations. Further, a flexible solid-state symmetric supercapacitor (SSSc) has been assembled taking LiCl/PVA gel electrolyte. The fabricated SSSc manifests a maximum energy density of 48.32 Wh/kg at a power density of 0.49 kW/kg. Moreover, the device exhibits 92% capacitance retention at a current density of 15 A/g after 10,000 cyclic performance. Interconnected network morphology with a large number of cavities/pores actually provides swift access of the electrolyte ions which utterly improves the performance of the electrode when it has been used for energy storage purposes.

Phosphonic Acid Coupling Agent Modification of HAP Nanoparticles: Interfacial Effects in PLLA/HAP Bone Scaffold.

In order to improve the interfacial bonding between hydroxyapatite (HAP) and poly-l-lactic acid (PLLA), 2-Carboxyethylphosphonic acid (CEPA), a phosphonic acid coupling agent, was introduced to modify HAP nanoparticles. After this. the PLLA scaffold containing CEPA-modified HAP (C-HAP) was fabricated by selective laser sintering (frittage). The specific mechanism of interfacial bonding was that the PO32− of CEPA formed an electrovalent bond with the Ca2+ of HAP on one hand, and on the other hand, the –COOH of CEPA formed an ester bond with the –OH of PLLA via an esterification reaction. The results showed that C-HAP was homogeneously dispersed in the PLLA matrix and that it exhibited interconnected morphology pulled out from the PLLA matrix due to the enhanced interfacial bonding. As a result, the tensile strength and modulus of the scaffold with 20% C-HAP increased by 1.40 and 2.79 times compared to that of the scaffold with HAP, respectively. In addition, the scaffold could attract Ca2+ in simulated body fluid (SBF) solution by the phosphonic acid group to induce apatite layer formation and also release Ca2+ and PO43− by degradation to facilitate cell attachment, growth and proliferation.