Sulfonated Poly Ether Ether Ketone Research Articles

Preparation and study on H–MoS2/SLS modified SPI@SPEEK blend proton exchange membrane with balanced proton conductivity and stability

Proton exchange membranes (PEMs) are the core components of fuel cells, and research has long focused on how to balance their proton conductivity and durability. In this work, a series of homogeneous blend of sulfonated polyimide (SPI) and sulfonated polyether ether ketone (SPEEK) hybrid membranes with were constructed refined with sulfonated MoS2 (H–MoS2) and sodium lignosulfonate (SLS). The results showed that the tensile strength of the films was enhanced by 39.4% (67.84 MPa) compared to the base film. The composite films incorporating 1 wt% H-MoS2 and 2 wt% SLS has excellent proton conductivity, which can reach 50.24 mS/cm at 80°C and 100% humidity. The embed hybrid structure constructed by H–MoS2 and SLS, which not only effectively solves the limitations of the proton transport channel of traditional polymer materials, but also provides abundant proton transport sites, which provides a new strategy for preparing high-performance PEM.

Graphene Oxide-Silver-Coated Sulfonated Polyetheretherketone (Ag/GO-SPEEK): A Broad-Spectrum Antibacterial Artificial Bone Implants.

Polyetheretherketone (PEEK), particularly its sulfonated form (SPEEK), has emerged as a promising synthetic biomaterial for artificial bone implants, providing an alternative to conventional titanium metal. However, postoperative infections pose a critical challenge, driven by diverse and antibiotic-resistant bacteria. To address this issue, we propose the modification of the SPEEK surface using a thin graphene oxide (GO) film containing silver (Ag) ions. The resulting coating exhibits substantial antibacterial effects against various pathogens, including Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Candida albicans. Experimental assessments elucidate the coating's impact on bacterial adhesion, biofilm formation, and morphology. The results suggest that hindered bacterial growth stems from reduced biofilm production and the controlled release of Ag ions facilitated by the GO coating. The Ag/GO-SPEEK material holds promise as a bioactive implant, addressing the challenges associated with bacterial targeting in bone tissue engineering applications.

Preparation of modified atmosphere packaging based on the respiratory characteristics of cherry tomato and its freshness preservation application

Cherry tomato (Lycopersicon esculentum Mill.) belongs to the respiratory leap type of fruit, post-harvest respiratory metabolism exuberant, easy to lead to nutrient loss, tissue destruction, and then rotting and deterioration, seriously affecting its commercial value. Therefore, research on post-harvest preservation technology of cherry tomatoes is crucial for related industries. Spontaneous modified atmosphere film packaging technology can extend the storage period of fruits and vegetables by adjusting the gas concentration of the storage environment, so that the fruits and vegetables can be maintained at a level suitable for their storage. In this study, the respiration model of cherry tomatoes at different temperatures was established by measuring the respiration rate of cherry tomatoes at different temperatures. It was found that the respiration rate of cherry tomatoes increased with increasing temperature and gradually decreased with increasing storage time. T-test results showed that there was no significant difference between the experimental values and the predicted values. The chemical kinetic model and its equilibrium equation were used to determine the parameters of modified atmosphere packaging of cherry tomatoes. PEG/PVDF membranes and SPEEK/PEG/PVDF blend membranes were prepared with sulfonated polyether ether ketone (SPEEK), polyvinylidene fluoride (PVDF) and polyethylene glycol (PEG) according to the parameters of modified atmosphere membranes to keep cherry tomatoes fresh. The results showed that there was a significant effect of package method on the preservation parameters of cherry tomatoes, the SPEEK/PEG/PVDF membrane treatment group significantly reduced the weight loss rate of cherry tomatoes and maintained the lower film permeability and higher sound fruit rate, hardness, titratable acid (TA) content, VC content and total soluble solids (TSS) content of cherry tomatoes. It can effectively delay the ripening and senescence of cherry tomatoes and extend the fruit storage period.

Induced Anionic Functional Group Orientation-Assisted Stable Electrode-Electrolyte Interphases for Highly Reversible Zinc Anodes.

Dendrite growth and other side-reaction problems of zinc anodes in aqueous zinc-ion batteries heavily affect their cycling lifespan and Coulombic efficiency, which can be effectively alleviated by the application of polymer-based functional protection layer on the anode. However, the utilization rate of functional groups is difficult to improve without destroying the polymer chain. Here, a simple and well-established strategy is proposed by controlling the orientation of functional groups (─SO3H) to assist the optimization of zinc anodes. Depending on the electrostatic effect, the surface-enriched ─SO3H groups increase the ionic conductivity and homogenize the Zn2+ flux while inhibiting anionic permeation. This approach avoids the destruction of the polymer backbone by over-sulfonation and amplifies the effect of functional groups. Therefore, the modified sulfonated polyether ether ketone (H-SPEEK) coating-optimized zinc anode is capable of longtime stable zinc plating/stripping, and moreover an enhanced cycling steadiness under high current densities is also detected in a series of Zn batteries with different cathode materials, which achieved by the inclusion of H-SPEEK coating without causing any harmful effects on the electrolyte and cathode. This work provides an easy and efficient approach to further optimize the plating/stripping of cations on metal electrodes, and sheds lights on the scale-up of high-performance aqueous zinc-ion battery technology.

Preparation and Characterization of SPEEK–PVA Blend Membrane Additives with Colloidal Silica for Proton Exchange Membrane Fuel Cell

AbstractAn inexpensive membrane with high proton conductivity and high fuel cell performance, which can be an alternative to Nafion for PEMFC (Proton exchange membrane fuel cell), will overcome the obstacle to widespread commercialization of fuel cells due to high cost. For this purpose, SPEEK (sulfonated polyether ether ketone)-PVA (polyvinyl alcohol) blend membranes with colloidal silica additives were synthesized in this study. Ludox AS-40 was used as the colloidal silica source and the blend membrane was prepared by solution casting method. Water uptake capacity, swelling property, size change, dynamic mechanical analysis, ion exchange capacity, AC impedance analysis, hydrolytic and oxidative stability experiments of the synthesized Ludox additives blend membranes for fuel cell application were carried out, and the membranes were also characterized by FTIR (Fourier transform infrared) analysis. While the water uptake capacities of SPEEK/PVA membranes containing 1% Ludox, 5% Ludox, and 10% Ludox at room temperature were found to be 14.08%, 14.84%, and 16.6%, respectively, the water uptake capacities at 80oC increased to 14.73%, 15.17%, and 17.11%. The proton conductivities of 1% Ludox, 5% Ludox and 10% Ludox doped SPEEK/PVA membranes at 80oC were 0.25 S/cm, 0.56 S/cm, and 0.65 S/cm, respectively. Similarly, ion exchange capacities were determined to be 1.41 meq/g, 1.63 meq/g, and 1.71 meq/g, respectively. All Ludox-added membranes exhibited excellent hydrolytic stability, retaining approximately 88% of their mass after 650 h. In addition, in oxidative stability experiments carried out in 4 ppm Fe+ 2 at 80oC, the 10% Ludox-added membrane exhibited the highest weight loss of 88.8% at the end of 24 h, while the 5% Ludox-additive membrane retained 91.6% of its total weight. Considering the proton conductivity and longevity tests of the synthesized membranes, they are thought to be promising structures. Graphical Abstract

In Vitro Evaluation of Optimized PEEK Surfaces for Enhanced Osseointegration

The materials traditionally used for implant applications, such as titanium alloys, cobalt chromium, and zirconium, often require surface modifications to achieve the desired osseointegration. These materials still have the problematic stress-shielding effect. To limit stress shielding, PEEK is the superior alternative to fulfill implant needs. However, the traditional methods of modifying and functionalizing the surface of PEEK are often expensive, time consuming, and are not easily translated into commercialization. Sulfonation is a process, which is dependent on controllable factors. Thus far, no research has been performed to optimize the sulfonation process. Our data suggest that the process factors can be controlled and optimized. Cellular activity was examined on the optimized PEEK surfaces through testing with pre-osteoblast MC3T3-E1 cells through cell viability (MTT assay), cell proliferation (DNA assay), cell differentiation (ALP assay), and cell mineralization (Alizarin red assay). Overall, sulfonated and heat-treated PEEK exhibited a statistically significant increase in DNA content over the course of 21 days, indicating more cell proliferation and viability for that surface. In vitro testing results showed that the optimized sulfonated and heat-treated PEEK exhibited superior cell proliferation and mineralization performance over smooth PEEK and sulfonated-only PEEK.

Homogeneous-strengthened SPEEK membrane with ultrahigh conductivity regulated by main/side-chain bisulfonated PEEK for vanadium flow battery

A comblike polymer (SPOS) with a main/side-chain bisulfonated structure has been synthesized with 1,3-propane sulfonate as the pendant chains and poly (ether ketone) (PEEK) as the reactant by the combined post-sulfonation and ring-opening grafting reaction. Taking sulfonated PEEK as a membrane matrix, the composite membranes (S/SPOS) are prepared by the solution-blending method with varied contents of bisulfonic SPOS polymer from 10 to 25 wt%. The S/SPOS composite membranes display superior conductivity owing to synergistic enhancement in the intermolecular chain interactions and the homogeneous strengthened transportation channels from main/side-chain bisulfonic acid interconnected networks. S/SPOS-15 shows better CE (96.5–98.5 %) and EE (84.7–69.9 %) than that of Nafion 212 (CE: 92.3–95.0 %, EE: 76.1–63.7 %) at 100–200 mA cm−2. Moreover, 600-cycled durability and 77.3 % EE at 150 mA cm−2, and 71.8 h self-discharge time demonstrate its improved reliable structure and cyclic stability. This provides a promising method to prepare high-performance and low-cost membranes with desirable conductivity by homogeneous structural regulation and molecular chain synergistic interactions.

Overcoming the Trade-Off between Methanol Rejection and Proton Conductivity via Facile Synthesis of Crosslinked Sulfonated PEEK Proton Exchange Membranes

In this work, homogeneous, thin-film proton exchange membranes (PEMs) with superior proton conductivities and high methanol rejection were fabricated via a facile synthesis procedure. Sulfonated polyether ether ketone (sPEEK) was crosslinked via a Friedel–Crafts reaction by α,α′-dichloro-p-xylene, a non-hazardous and hydrophobic compound. PEMs with varying crosslinking and sulfonation degrees were fabricated to overcome the traditional trade-off between methanol rejection and proton conductivity. The sulfonation of PEEK at 60 °C for 24 h resulted in a sulfonation degree of 56%. Those highly sulfonated backbones, in combination with a low membrane thickness (ca. 20 µm), resulted in proton conductivities superior to Nafion 117. Furthermore, X-ray photoelectron spectroscopy proved it was possible to control the crosslinking degree via the crosslinking time and temperature. The PEMs with the highest crosslinking degree showed better methanol rejection compared to the commercial benchmark. The introduction of the crosslinker created hydrophobic membrane sections, which reduced the water and methanol uptake. Subsequently, the membrane became denser due to the crosslinking, hindering the solute permeation. Those two effects led to lower methanol crossovers. This study proved the successful fabrication of PEMs overcoming the trade-off between proton conductivity and methanol rejection, following a facile procedure using low-cost and non-hazardous materials.

Tribological Behavior of Sulfonated Polyether Ether Ketone with Three Different Chemical Structures under Water Lubrication.

With the development of the shipbuilding industry, it is necessary to improve tribological properties of polyether ether ketone (PEEK) as a water-lubricated bearing material. In this study, the sulfonated PEEK (SPEEK) with three distinct chemical structures was synthesized through direct sulfonated polymerization, and high fault tolerance and a controllable sulfonation degree ensured the batch stability. The tribological and mechanical properties of SPEEK with varying side groups (methyl and tert-butyl) and rigid segments (biphenyl) were compared after sintering in a vacuum furnace. Compared to the as-made PEEK, as the highly electronegative sulfonic acid group enhanced the hydration lubrication, the friction coefficient and wear rate of SPEEK were significantly reduced by 30% and 50% at least without affecting the mechanical properties. And lower steric hindrance and entanglement between molecular chains were proposed to be partially responsible for the lowest friction behavior of SPEEK with methyl side groups, making it a promising and competitive option for water-lubricated bearings.

Functionalized microporous sulfonated polyetheretherketone: Osteogenesis and anti-osteoclastogenesis effects via ROS and NLRP3-mediated pyroptosis in macrophages

The treatment of osteoporotic implant failures tends to be challenging due to an imbalance in bone homeostasis. Recently, the accumulation of intracellular reactive oxygen species (ROS) and activation of the inflammasome containing nucleotide-binding oligomerization domain-like-receptor family pyrin domain-containing 3 (NLRP3) protein have been shown to indirectly affect osteogenesis and osteoclastogenesis. Owing to the release of multi-metal ions from laponite (LAP), we fabricated a multifunctional LAP coating on a three-dimensional microporous sulfonated polyetheretherketone (SPEEK) surface via polydopamine (PDA) modification (SPEEK@PDA-LAP). The balance between osteogenesis and osteoclastogenesis was examined using macrophages in an osteo-immune microenvironment. Employing in vitro assays, we showed that the SPEEK@PDA-LAP alleviated intracellular ROS accumulation and inhibited the activation of NLRP3 inflammasome-mediated pyroptosis in macrophages, creating an osteoimmunomodulatory microenvironment to stimulate osteogenesis and inhibit osteoclastogenesis. The micro-computed tomography and histological results of in vivo experiments indicated that SPEEK@PDA-LAP implants reversed the balance between osteogenesis and osteoclastogenesis to promote the formation of new bone around the implant even under osteoporotic conditions. The results indicate that inhibiting the NLRP3 inflammasome and regulating intracellular ROS in macrophages can be an effective therapy for osteoporosis. These results highlight the potential of functional PEEK materials for bone regeneration in patients with osteoporosis.

Anchoring of Fe-MIL-101-NH2 to the Polymer Membrane Matrix through the Hinsberg Reaction to Promote Conductivity of SPEEK Membranes.

SCPEEK@MOF proton exchange membranes, where SCPEEK is sulfinyl chloride polyether ether ketone and MOF is a metal-organic framework, were prepared by doping Fe-MIL-101-NH2 into polymers. The amino group in the MOF and the -SOCl2 group in thionyl chloride polyether ether ketone cross-link to form a covalent bond through the Hinsberg reaction, and the prepared composite membrane has stronger stability than other electrostatic interactions and simple physical doping composite membranes. The formation of covalent bonds improves the water absorption of the composite membrane, which makes it easy for water molecules to form hydrogen bonds. Moreover, SPEEK as a proton conductive polymer and the synergy of MOFs improve the proton conductivity of composite membranes. The composite membranes were characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The swelling rate, water absorption, mechanical stability, ion exchange capacity, and proton conductivity of the pure sulfonated polyether ether ketone (SPEEK) membrane were compared with those of the mechanically doped SPEEK/MOF membrane and the composite membrane SCPEEK@MOF doped with different ratios of Fe-MIL-101-NH2, and all of the SCPEEK@MOF showed superior performance. When the Fe-MIL-101-NH2 loading rate of the composite membrane is 2%, the proton conductivity of the composite membrane can reach 0.202 S cm-1 at 363 K and a 98% relative humidity, which is much higher than that of the SPEEK/MOF membrane obtained by simple physical doping under the same conditions.

Development of Aqueous Organic Flow Battery Using SPEEK Membrane and Eco-Friendly Electrolytes

Aqueous organic redox flow batteries (AORFBs) are a type of flow battery that offers a promising solution for energy storage, and one of the main issues is selecting low-cost membranes with high ion conductivity to enhance performance and efficiency. In this study, low-cost sulfonated poly ether ether ketone (SPEEK) membranes were fabricated using the casting method, with the polymer/solvent ratios of SPEEK and N,N'-dimethylformamide (DMF) being varied. The Nafion 117 membrane was used as a benchmark for comparison. The performance of aqueous organic redox flow batteries employing anthraquinone-2-sulfonic acid (AQS) and 1,2-benzoquinone-3,5-disulfonic acid (BQDS) as electrolytes was evaluated. The SPEEK membranes were determined to have dense, homogeneous surfaces with no flaws and a thickness of 60 microns. In addition, their physicochemical properties, such as water uptake, swelling ratio, ion exchange capacity, and degree of sulfonation, were investigated. The results showed that the SPEEK membranes had better rate performance and cycle stability when compared to the Nafion117 membrane during charge-discharge cycles. Additionally, the SPEEK membranes exhibited slower potential drops and higher power density during constant current mode operation, despite showing no significant differences in energy efficiency and power density. These findings demonstrate the potential of SPEEK membranes for use in AORFBs and as a benchmark for future research and development.

SYNTHESIS OF POLYMER ELECTROLYTE MEMBRANES BASED ON IONIC LIQUID DOPED SPEEK

The sustainable and environmentally benign energy demand of the world has been increasing. Among the various options, proton exchange membrane fuel cell is an attractive choice for energy supply due to its high efficiency and application conditions without waste. In this research, triazole-based ionic liquid doped sulfonated polyether ether ketone (SPEEK) composite membranes were presented for proton exchange membrane fuel cell (PEMFC) applications. Composite membranes were prepared by incorporating 1,2,3-triazole-based ionic liquids (TIL 1-2-3) into poly(ether ether ketone) (PEEK) matrices. The mechanical, structural, and thermal properties of both composite membranes and the triazole-based ionic liquids were thoroughly characterized using dynamic mechanical analysis (DMA), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The performance and viability of composites for PEMFC applications that involve elevated temperatures were conducted by proton conductivity test across a broad range of temperatures (30-180 oC). High-temperature proton conductivity was measured as 1.73x10-2 S/cm for SPEEK/TIL-3(1.0). According to the proton conductivity test results, it was concluded that the composite membranes may exhibit improved performance in PEMFC applications due to increased proton conductivity values.

Review of SPEEK Amphoteric Proton Exchange Membranes in All Vanadium Flow Batteries

Sulfonated polyether ether ketone (SPEEK) membranes have been widely used in the field of all vanadium flow batteries (VFRB) due to their simple structure, convenient preparation, good thermal and mechanical stability, low cost, and easy modification. However, its membrane performance largely depends on the degree of sulfonation. As the degree of sulfonation increases, the proton conductivity increases, but it also increases water uptake, leading to excessive swelling and vanadium ion penetration, thereby reducing the stability of the membrane and the performance of the battery. The introduction of alkaline functional groups can serve as proton acceptors to promote proton transport through the Grotthus mechanism, and on the other hand, they can form acid-base pairs with sulfonic acid groups. The resulting hydrogen bonds, acid-base interactions, ion bonds, and other interface interactions are beneficial for reducing the swelling rate of SPEEK membranes, and can also adjust the size of proton transport channels, constructing efficient proton transport channels that are both conducive to proton transport and can hinder the passage of vanadium ions, Improve the ion selectivity of membranes. Therefore, this article reviews the basic research and practical development status of SPEEK amphoteric membranes in VRFB, including the latest progress in various modification strategies. And evaluated the challenges and potential future research directions faced by the development of SPEEK membranes.

MnFe2O4/graphene oxide modified PEEK with phototherapeutic and GPx-mimetic potential for anti-bacterial treatment

Polyetheretherketone (PEEK) as a promising orthopaedic alternative possesses excellent mechanical properties and biocompatibility. However, the scarcity of anti-pathogenic property limits its clinical application. In this work, the MnFe2O4/graphene oxide (MFO/GO) nanosheets were hydrothermally fabricated and further decorated on sulfonated PEEK (SP) substrate mediated by polydopamine for the preparation of SP-P-MFO/GO. The results show that the sample exhibits glutathione oxidase-mimetic activity, which can catalyze glutathione to oxidized glutathione for reactive oxide species accumulation to kill bacteria. Additionally, the favorable photothermal effect can generate a local hyperthermic microenvironment for enhancing bacterial inhibition. The antibacterial tests in vitro reveal that the SP-P-MFO/GO possesses about 99.99% bactericidal rate against both E. coli and S. aureus with near infrared laser irradiation. This work provides a potential strategy for the healing of bacteria-invaded bone tissue.

Construction of thermal, chemical and mechanically stable ion exchange membranes with improved ion selectivity for vanadium redox flow batteries applications

As an alternative to expensive Nafion membrane, SPEEK (Sulfonated Poly Ether Ether Ketone) membrane reinforced with hydroxylated boron nitride is investigated as a potential proton exchange membrane for vanadium redox flow battery (VRFB). SPEEK based hybrid membranes are characterized for their thermal, mechanical and chemical stability along with proton conductivity and vanadium permeability. The results reveal that the hydroxylated boron nitride enhances the physicochemical properties of SPEEK and shown to improve selectivity of ions (52.629 *103. S.cm−3.min) with better stability. The improved properties are attributed to hydrogen bond formation between hydroxyl moieties of born nitride and sulfonic acid group in SPEEK. Among the hybrid membrane, SPEEK reinforced with 0.05 wt % of hydroxylated boron nitride exhibits a higher coulombic efficiency of 93.6 % (91.8 % for Nafion), higher self-discharge time of 14.21 h (11.36 h for Nafion) in VRFB single cell performance study. Cyclic performance study in VRFB with hybrid membrane shows stable characteristics during 50 cycles and it reaffirms the structural, thermal and chemical stability of hybrid membranes. Thus, this study provides insight into replacing commercial Nafion with hydroxylated boron nitride reinforced SPEEK hybrid membrane for vanadium redox flow battery.

Cost estimation and performance evaluation of 3D printed membranes for vanadium redox flow batteries

AbstractThe membrane is a central component in the commercialization of vanadium redox flow batteries (VRFB), with Nafion being the preferred material for those membranes. Nafion suffers however from high vanadium crossover and high cost, thus limiting its wider commercial application in VRFB. To address this, studies have focused on sulfonated polyether ether ketone (SPEEK) as an alternative material. This work presents an economic study on the production costs of 3D printed SPEEK (3D‐SPEEK) membranes for VRFB, with multiple production scenarios evaluated. This analysis relies on the performances of 3D‐SPEEK membranes prepared in our laboratory, which have shown higher Coulombic efficiency and lower vanadium ions diffusion than Nafion membranes. Results from the economic analysis revealed that the cost of the 3D‐SPEEK membrane varies from 567.77 to 79.35 €/m2 depending on the production scheme and scale used. Production costs lower than commercial Nafion membranes are achieved when a large production scheme is used. Further analysis shows that 3D‐SPEEK membranes might even be cheaper than conventional SPEEK membranes if their printing time is reduced.

NH2-UiO66 functionalized polyimide nanofiber to anchor HPW and fabricate high-performance sandwich-structure membrane for achieving excellent durability

Sulfonated poly ether ether ketone (SPEEK) was used to fabricate proton exchange membrane (PEM) due to its adaptable proton conductivity. However, PEM cannot simultaneously enhance its conductivity and stability. To solve the problem mentioned above, phosphotungstic acid (HPW) with strong inherent proton conductivity was chosen to add to the SPEEK matrix, but it still faces the leaky problem. NH2-UiO-66 (NU6) with a large surface area and chemical stability was synthesized in situ on the surface of polyimide (PI) nanofiber to create NU6@PI nanofiber, which can be used to anchor HPW. Meanwhile, the stability of proton transport channel may be further enhanced by the sandwich structure, which may be advantageous for proton transport. The NU6@PI/SPEEK + HPW-20 exhibited a conductivity of 174.9 mS·cm−1 and a swelling ratio of 19 % at 60 °C and 100 % RH. After 6 weeks of testing, its conductivity decreased to 151.2 mS·cm−1 which was 24 % higher than that of SPEEK, while the swelling ratio increased to 31 % which was lower than that of SPEEK. The outcome demonstrates that the sandwich-structure NU6@PI/SPEEK + HPW membrane may really boost proton conductivity and stability at the same time. By using XPS and TEM, it is possible to confirm the acid-base interaction and acid-rich layer that exist at the interfaces of NU6@PI nanofiber and HPW/SPEEK matrix. After 6-weeks of usage, the sandwich-structure composite membrane with nanofiber at both the top and bottom of PEM can still maintain high proton conductivity and high stability, offering a novel research idea for resolving the issue that PEM cannot simultaneously achieve significant proton conductivity as well as elevated stability.

Construction of Cation-Sieving Function Layers Enabling Dendrite-Free Zinc Metal Anodes for Durable Aqueous Systems.

Rechargeable aqueous zinc-ion batteries are considered as promising candidates for safe and green energy storage. Yet, Zn anodes still suffer from serious challenges. Herein, an effective cation-sieve of polyethersulfone-modified sulfonated polyether ether ketone is developed as protective coating layer of the Zn anodes. Cation-only transmission and dense property of the layer can protect the Zn from active water and anions, inhibiting corrosion, hydrogen evolution reaction (HER), and passivation. Zincophilic property of the layer can homogenize Zn2+ flow, and promote uniform plating of Zn. Therefore, protected symmetric Zn||Zn cell can maintain as long as 5600h with a low polarization at 1.0mA cm-2 and 0.5 mAh cm-2 , and still long as 800h at 5.0mA cm-2 and 5.0 mAh cm-2 . It is found that not only the dendrites but also the popular existed passivation product of Zn4 SO4 (OH)6 ·5H2 O can be inhibited effectively. In asymmetric Zn||Ti cells, average Coulombic efficiency can reach 98.2%, suggesting corrosion and HER are restrained effectively. Matched with MnO2 cathode, full cells using coated Zn exhibit much better cycling performance than that using bare Zn. Moreover, Zn4 O3 (SO4 )·7H2 O (ZSH)-assisted reversible conversion mechanism between the ZSH and Znx Hy MnO2 is revealed through operando Raman.

Antimicrobial Peptide Conjugated on Graphene Oxide-Containing Sulfonated Polyetheretherketone Substrate for Effective Antibacterial Activities against Staphylococcus aureus.

In the present study, the antimicrobial peptide nisin was successfully conjugated onto the surface of sulfonated polyetheretherketone (SPEEK), which was decorated with graphene oxide (GO) to investigate its biofilm resistance and antibacterial properties. The PEEK was activated with sulfuric acid, resulting in a porous structure. The GO deposition fully covered the porous SPEEK specimen. The nisin conjugation was accomplished using the crosslinker 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) through a dip-coating method. The surface micrographs of the SPEEK-GO-nisin sample indicated that nisin formed discrete islets on the flat GO surface, allowing both the GO and nisin to perform a bactericidal effect. The developed materials were tested for bactericidal efficacy against Staphylococcus aureus (S. aureus). The SPEEK-GO-nisin sample had the highest antibacterial activity with an inhibition zone diameter of 27 mm, which was larger than those of the SPEEK-nisin (19 mm) and SPEEK-GO (10 mm) samples. Conversely, no inhibitory zone was observed for the PEEK and SPEEK samples. The surface micrographs of the bacteria-loaded SPEEK-GO-nisin sample demonstrated no bacterial adhesion and no biofilm formation. The SPEEK-nisin and SPEEK-GO samples showed some bacterial attachment, whereas the pure PEEK and SPEEK samples had abundant bacterial colonies and thick biofilm formation. These results confirmed the good biofilm resistance and antibacterial efficacy of the SPEEK-GO-nisin sample, which is promising for implantable orthopedic applications.