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Background. Rheumatoid arthritis (RA) is recognized as a chronic inflammatory disease featured by pathological synovial inflammation. Currently, the underlying pathophysiological mechanisms of RA remain unclear. In the study, we attempted to explore the underlying mechanisms of RA and provide potential targets for the therapy of RA via bioinformatics analysis. Methods. We downloaded four microarray datasets (GSE77298, GSE55235, GSE12021, and GSE55457) from the GEO database. Firstly, GSE77298 and GSE55457 were identified DEGs by the “limma” and “sva” packages of R software. Then, we performed GO, KEGG, and GSEA enrichment analyses to further analyze the function of DEGs. Hub genes were screened using LASSO analysis and SVM-RFE analysis. To further explore the differences of the expression of hub genes in healthy control and RA patient synovial tissues, we calculated the ROC curves and AUC. The expression levels of hub genes were verified in synovial tissues of normal and RA rats by qRT-PCR and western blot. Furthermore, the CIBERSORTx was implemented to assess the differences of infiltration in 22 immune cells between normal and RA synovial tissues. We explored the association between hub genes and infiltrating immune cells. Results. CRTAM, CXCL13, and LRRC15 were identified as RA’s potential hub genes by machine learning and LASSO algorithms. In addition, we verified the expression levels of three hub genes in the synovial tissue of normal and RA rats by PCR and western blot. Moreover, immune cell infiltration analysis showed that plasma cells, T follicular helper cells, M0 macrophages, M1 macrophages, and gamma delta T cells may be engaged in the development and progression of RA. Conclusions. In brief, our study identified and validated that three hub genes CRTAM, CXCL13, and LRRC15 might involve in the pathological development of RA, which could provide novel perspectives for the diagnosis and treatment with RA.

Fabricating covalent organic frameworks (COFs) membranes with tight structure, which can fully utilize well-defined framework structure and thus achieve superior conduction performance, remains a grand challenge. Herein, through molecular precursor engineering of COFs, we reported the fabrication of tight COFs membrane with the ever-reported highest hydroxide ion conductivity over 200 mS cm-1 at 80 °C, 100 % RH. Six quaternary ammonium-functionalized COFs were synthesized by assembling functional hydrazides and different aldehyde precursors. In an organic-aqueous reaction system, the impact of the aldehyde precursors with different size, electrophilicity and hydrophilicity on the reaction-diffusion process for fabricating COFs membranes was elucidated. Particularly, more hydrophilic aldehydes were prone to push the reaction zone from the interface region to the aqueous phase of the reaction system, the tight membranes were thus fabricated via phase-transfer polymerization process, conferring around 4-8 times the anion conductivity over the loose membranes via interfacial polymerization process.

Constructing long-range proton-transfer pathways with sufficient conducting sites in proton exchange membranes (PEMs) is vital for proton conduction. Herein, phosphotungstic-acid-coupled graphene o...

Objective: The clinical symptoms of rheumatoid arthritis (RA) have significant circadian rhythms, with morning stiffness and joint pain. Moxibustion is effective in the treatment of RA, while the underlying therapeutic mechanisms remain limited. Thus, we explored whether moxibustion could adjust the circadian rhythm of RA by modulating the core clock genes CLOCK and BMAL1 at the molecular level. Methods: 144 Sprague Dawley rats were randomly divided into four groups: control group (group A), model group (group B), 7-9 am moxibustion treatment group (group C), and 5-7 pm moxibustion treatment group (group D). Each group was divided into 6 time points (0 am, 4 am, 8 am, 12 N, 6 pm, and 8 pm) with an equal number of rats at each time point. Except for group A, all rats were injected with Freund’s Complete Adjuvant (FCA) 0.15 ml on the right foot pad to establish the RA model. The rats of the two moxibustion treatment groups were respectively subjected to moxibustion at 7-9 am and 5-7 pm. After 3 weeks of treatment, the tissues were collected at 6 time points during the next 24 hours. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to test the mRNA expression of CLOCK and BMAL1 in the hypothalamus and synovial tissues. CLOCK and BMAL1 protein expression in synovial tissues were detected with western blot. Results: Compared to group A, group B showed significantly down-regulated expression levels of CLOCK and BMLA1 at synovial tissue (P < 0.05), while no statistically significant difference was found in the hypothalamus (P > 0.05). The expression levels of CLOCK and BMLA1 were up-regulated in the moxibustion treatment groups in different tissues, especially in synovial tissue (P < 0.05) compared to group B. Nevertheless, no difference was observed between groups C and D (P > 0.05). Conclusions: Moxibustion could treat RA by modulating clock core genes CLOCK and BMAL1 to regulate the circadian rhythm. However, there was no significant difference between the 7-9 am moxibustion treatment group and the 5-7 pm moxibustion treatment group. This study provides a basis for research on moxibustion in the treatment of RA.

Developing novel proton conductors is crucial to the electrochemical technology for energy conversion and storage. Metal-organic frameworks (MOFs), with a highly ordered and controllable structure, have been widely explored to prepare high-performance proton conductors. Albeit the prominent merits and great potential of the MOF-based materials such as MOF pellets or composite polymer electrolytes, constructing well-defined proton-transfer channels with much lower grain boundary resistance and more homogeneous distribution deserves extensive explorations. Herein, a kind of nanostructured metal-organic gel (MOG) with a three-dimensional (3D) interconnected proton-conductive network is prepared by a facile sol-gel method using Cr

Graphene oxide (GO) membranes with 2D interlaminar channels have triggered intensive interest as ion conductors. Incorporating abundant ion-conducting sites into GO interlayers is recognized as an effective strategy to facilitate ion conduction. Herein, we designed supramolecular compounds, para-sulphonato-calix[n]arenes (p-SC[n]As), as versatile intercalators to acquire highly conductive and robust GO membranes. The SC[n]A with ultrahigh ionic exchange capacity (IECw, 5.37 mmol g-1) imparts sufficient proton donors, and its rigid framework imparts strong support of adjacent nanosheets. We designed three kinds of SC[n]As with the same IECw but different sizes as intercalators, endowing the GO/SC[n]A membranes with increasing ion concentration and d-spacing in the order of GO/SC[4]A < GO/SC[6]A < GO/SC[8]A. Therefore, the interlayers of GO/SC[8]A membranes afforded higher density of proton donors and could accommodate more water molecules to construct more continuous H-bond networks for proton transfer. Accordingly, the proton conductivities exhibited the same increasing trend, up to 327.0 mS cm-1 of GO/SC[8]A-30% at 80 °C, 100% RH, which was 2.80 times higher than that of the GO membrane. Moreover, the GO/SC[n]A membranes remained stable in wet state, along with a 66% elevation in mechanical performance compared to the GO membrane.

Simultaneously improving the hydroxide conduction capacity and anti-swelling property of anion exchange membranes (AEM) is a big challenge in the field of fuel cells. In this work, the poly (vinyl imidazole) functionalized carbon nanotube (PVI@CNT) was synthesized as a dual functional nanofiller and introduced into the imidazole poly(ether ether ketone) (IPEEK) matrix. The imidazolium groups on the PVI@CNT offer additional ion conducting sites to improve the hydroxide conductivity. The imidazolium groups also react with the IPEEK to form a crosslinking structure along the nanotubes, thus ensuring favorable anti-swelling property. The nanohybrid membrane with 15 wt % PVI@CNT (IPEEK/PVI@CNT-15) shows a maximum conductivity of 121 mS cm -1 at 70 o C, 100% relative humidity (RH). Meanwhile, the crosslinking structure suppresses the swelling degree from 42.0% (pristine IPEEK) to 17.8% (IPEEK/PVI@CNT-15). The single H 2 /O 2 fuel cell performance of the membrane electrode assembly (MEA) with IPEEK/PVI@CNT-15 membrane reveals a high power density of 128.7 mW cm −2 . Moreover, the incorporation of the PVI@CNT also enhances the alkali stability and the thermal stability of the nanohybrid membranes.

Development of proton exchange membranes with sufficiently high proton conductivity, especially at low relative humidity (RH), remains a big challenge in the field of fuel cells. In this study, gra...

Nanofiltration is a promising technology towards desalination and water purification. However, the pursuit for separation efficiency was hampered by the thick and less controllable selective layer. Herein, the ultrathin composite membranes with enhanced nanofiltration (NF) performance were achieved by interfacial polymerization mediated by polydopamine (PDA)-covalent organic framework (COF) interlayer. The hybrid interlayer with exceptional surface hydrophilicity and high porosity controlled the adsorption/diffusion of amine monomers during the interfacial polymerization process and generated an ultrathin and dense polyamide (PA) layer, which was immensely reduced from 79 nm to 11 nm in thickness. The PA/PDA-COF/PAN nanofiltration membrane exhibited desirable desalination ratio (93.4% for Na2SO4) and dye rejection (94.5% for Orange GII), along with outstanding water permeation flux of 207.07 L m−2 h−1 MPa−1, 3 times higher than that of commercial NF membranes with similar solute rejection. Moreover, the hybrid interlayer significantly strengthened the interfacial interaction between the PA layer and the polyacrylonitrile (PAN) support, rendering the composite membrane with superior structural stability. The proposed strategy provided novel insight into the rational design of multifunctional interlayer to manipulate interfacial polymerization for high-performance PA membranes.

An effective strategy to improve both the conductivity and alkaline stability of anion exchange membranes (AEMs) was proposed by incorporating imidazolium ionic liquids (ImILs) modified 1D carbon nanotubes (IL@CNT) into imidazolium-based poly (ether ether ketone) (ImPEEK). Two types of ionic liquids (IL-M and IL-B) with different alkaline stability were chemically attached to CNTs. The introduction of IL@CNT provided the hybrid membranes with additional ion hopping positions and 1D long-range ion-conducting channels. The ImPEEK/IL-B@CNT-6 membrane with a high ion exchange capacity (IEC) of 2.49 mmol g−1 possessed the hydroxide conductivity of 134.52 mS cm−1 (70 °C, 100% RH) which was 1.7 times that of the pure ImPEEK membrane (80.20 mS cm−1). Meanwhile, the hybrid membranes showed enhanced alkaline stability due to the steric hindrance offered by CNTs and good alkaline resistance of IL-B with more bulky substituents. The residual ratio of hydroxide conductivity of ImPEEK/IL-B@CNT-8 after being treated in 2 M KOH at 50 °C for 48 h reached 77.47% (54.37% for pure ImPEEK and 70.21% for ImPEEK/ILM@CNT-8). The theoretical calculations of LUMO energy for IL-M (−1.83 eV) and IL-B (−1.74 eV) were in good accordance with experimental results. The ImPEEK/IL-B@CNT-6 hybrid membrane presented an improved fuel cell performance with the peak power density of 80.59 mW cm−2 at 50 °C which was 1.6 times that of the pure ImPEEK membrane. Mechanical properties, dimensional and thermal stability of the as-prepared hybrid membranes were also enhanced due to the improved interface compatibility.

The recent boom in human–machine interaction has triggered a significant demand for flexible and transparent ionotronics. State-of-the-art ion conductors are built by embedding electrolytes in a transparent gel polymer to form an ion-conducting composite, named ion conductive hydrogels or ionogels. Herein, we demonstrate an intrinsic ion-conducting membrane with ultrahigh ion conductivity, flexibility and transparency based on two-dimensional nanoclays of intrinsic conductivity (NICs). The inherently charged and ordered laminar microstructure exhibits an ultrahigh ion conductivity of 0.45 S cm−1 at 80 °C without external electrolytes, which is 100–1000 times higher than that of state-of-the-art ion-conducting composites. The NICs membranes also exhibit superior stability against harsh conditions including organic solvents, high temperature and prolonged dehydration–hydration cycles. We further demonstrate a NICs touch panel that can realize real-time, human–machine communication by drawing and typing. The nanoclays with intrinsic conductivity may open an avenue to electrolyte-free transparent and flexible ionotronics.

The construction of efficient proton transport channels in ion-conductive membranes is crucial to proton exchange membrane fuel cells (PEMFCs). Herein, zwitterion-functionalized covalent organic framework (Z-COF) with both ammonium groups and sulfonic acid groups was synthesized and blended with Nafion to prepare Nafion/Z-COF composite proton exchange membranes. The polymer-like feature of the Z-COF imparted favorable interactions between Z-COF and Nafion, and thus promoted the dispersion of Z-COF and the reorganization of ion clusters. The incorporation of Z-COF enhanced water retention property and the sulfonic groups on Z-COF provided additional proton-transport sites within the membranes. As a result, the low-energy-barrier paths for proton transport were created. The composite membranes with 10 wt% of Z-COF exhibited the highest proton conductivity of 0.22 S cm−1 at 80 °C and 100% RH, which was 57.1% higher than that of recast Nafion membrane. The enhanced proton conductivity also afforded the composite membrane a 45.7% increase in maximum power density of single fuel cell at 80 °C and 50% RH. The effects of Z-COF loading on membrane morphology, polymer chain mobility, thermal stability, water uptake and dimensional stability were also investigated.

State-of-the-art proton exchange membranes (PEMs) often suffer from significantly reduced conductivity under low relative humidity, hampering their efficient application in fuel cells. Covalent organic frameworks (COFs) with pre-designable and well-defined structures hold promise to cope with the above challenge. However, fabricating defect-free, robust COF membranes proves an extremely difficult task due to the poor processability of COF materials. Herein, a bottom-up approach is developed to synthesize intrinsic proton-conducting COF (IPC-COF) nanosheets (NUS-9) in aqueous solutions via diffusion and solvent co-mediated modulation, enabling a controlled nucleation and in-plane-dominated IPC-COF growth. These nanosheets allow the facile fabrication of IPC-COF membranes. IPC-COF membranes with crystalline, rigid ion nanochannels exhibit a weakly humidity-dependent conductivity over a wide range of humidity (30-98%), 1-2 orders of magnitude higher than that of benchmark PEMs, and a prominent fuel cell performance of 0.93 W cm-2 at 35% RH and 80 °C arising from superior water retention and Grotthuss mechanism-dominated proton conduction.

The heterogeneity of disease is a major concern in medical research and is commonly characterized as subtypes with different pathogeneses exhibiting distinct prognoses and treatment effects. The classification of a population into homogeneous subgroups is challenging, especially for complex diseases. Recent studies show that gut microbiome compositions play a vital role in disease development, and it is of great interest to cluster patients according to their microbial profiles. There are a variety of beta diversity measures to quantify the dissimilarity between the compositions of different samples for clustering. However, using different beta diversity measures results in different clusters, and it is difficult to make a choice among them. Considering microbial compositions from 16S rRNA sequencing, which are presented as a high-dimensional vector with a large proportion of extremely small or even zero-valued elements, we set up three simulation experiments to mimic the microbial compositional data and evaluate the performance of different beta diversity measures in clustering. It is shown that the Kullback-Leibler divergence-based beta diversity, including the Jensen-Shannon divergence and its square root, and the hypersphere-based beta diversity, including the Bhattacharyya and Hellinger, can capture compositional changes in low-abundance elements more efficiently and can work stably. Their performance on two real datasets demonstrates the validity of the simulation experiments.

Background: Heterogeneity of disease is a major concern in medical research, which is commonly recognized as subtypes with different pathogenesis, exhibiting distinct prognosis and treatment effects. The classification of population into homogenous subgroups is challenging, especially for the complex diseases. Recent studies show that gut microbiome compositions play a vital role in disease development, and it is of great interest to cluster the patients according to their microbial profiles. There are a variety of beta diversity measures to quantify the dissimilarity between the compositions of different samples for clustering. However, using different beta diversity measures results in different clusters, and it is difficult to make a choice. Results: Considering the microbial compositions from 16S rRNA sequencing, which are presented as a high-dimensional vector with large proportion of extremely small or even zero-valued elements, we set up three simulation experiments to mimic the microbial compositional data and evaluate the performance of different beta diversity measures in clustering. Their performance in two real datasets demonstrates the validity of the simulation experiments. Conclusion: It is shown that J-divergence/Jensen-Shannon divergence/square root of Jensen-Shannon divergence and Bhattacharyya/Hellinger can capture the compositional changes at low abundance elements more efficiently, and Bhattacharyya/Hellinger is suggested.

The enhancement of hydroxide conductivity in anion exchange membrane fuel cells is of great urgency. Incorporation of fillers with abundant ion exchange groups into polymer electrolyte offers availability to robust membranes with improved ion conductivity. In this study, imidazolium-functionalized graphene oxide (ImGO) was prepared by polydopamine coating on the pristine graphene oxide sheets and subsequent reaction with imidazolium. Then, the ImGO was incorporated into imidazolium-functionalized poly(ether ether ketone) (ImPEEK) matrix to fabricate ImPEEK/ImGO hybrid membranes. Benefiting from the abundant imidazolium groups on ImPEEK and ImGO, the ImPEEK/ImGO hybrid membrane possesses a high ion exchange capacity up to 2.59 mmol g−1 with a moderate water uptake and good mechanical strength simultaneously. The interconnected hydrogen-bonded networks formed between the functional groups and the absorbed water contribute to the maximum hydroxide conductivity of 0.14 S cm−1 at 70 °C and 100% RH at the ImGO loading content of 4 wt%. The ImPEEK/ImGO-4 hybrid membrane shows an improved fuel cell performance with the power density of 50.04 mW cm−2 at 50 °C which is 122% higher than that of the pristine ImPEEK membrane. Moreover, the alkaline and thermal stability of the hybrid membranes are also enhanced.

Anion-exchange membranes (AEM) are prepared from chloromethylated poly(ether ether ketone) (CMPEEK), which is quaternized by N,N,N′,N′-tetramethyl-1,4-phenylenediamine (TMPD) and 1-methylimidazole using a two-step method. TMPD can not only improve the mechanical properties but also provide more ion exchange groups and improve the availability of quaternary ammonium (QA) groups. By varying the amount of TMPD in the membrane casting solution, the comprehensive properties of the membranes are optimized and intensified. The anion conductivity is increased from 0.028 S cm−1 of the imidazolium functionalized poly (ether ether ketone) (ImPEEK) control membrane to 0.042 S cm−1 of the TMPD/ImPEEK membrane with a TMPD content of 5 wt%. Meanwhile, a 31.5% increase in ultimate tensile strength and a 27.8% increase in Young's modulus of the TMPD/ImPEEK membrane are achieved. This study exploited a facile approach to solving the trade-off relation between anion conductivity and mechanical properties.

Fast proton transport, good stability and high fuel-blocking property in solid polyelectrolytes is of critical significance for a number of energy-conversion devices. However, the simultaneous enhancement of these properties has proved to be extremely challenging. Herein, we report a novel strategy to remarkably increase the comprehensive properties of Nafion-based mixed-matrix polyelectrolyte membranes through engineering organic-inorganic interfaces using amphiphilic block copolymer functionalized nanoparticles, SiO2 nanoparticles grafted with sulfonated polystyrene-b-polyperfluroallylbenzene. The amphiphilic block copolymer on nanoparticles imparts favorable interactions between the nanoparticles and amphiphilic Nafion, and thus facilitates the dispersion of nanoparticles and the reorganization of ion clusters. As a result, the mixed-matrix polyelectrolyte membrane with 2.5 wt% filler loading exhibits proton conductivities of 327 mS cm−1 at 80 °C, 100% RH, and 63 mS cm−1 at 80 °C, 50% RH, which is one of the highest proton conductivities ever reported. Moreover, the membrane also shows pronounced enhancements in thermal stability, dimensional stability, methanol-blocking property, and mechanical strength, in comparison with those of Nafion.

Layered double hydroxides (LDH), bearing trivalent cationic charge centers and hydroxyl slabs, hold great promise for use in efficient solid-state ion conductors. In this study, a composite membrane with ion-conducting 2D channels was prepared based on exfoliated LDH nanosheets and quaternized polyvinyl alcohol via a filtration process. The LDH laminates, which were formed by the stacking of exfoliated LDH nanosheets, primarily afforded the conductive performance of the membranes. Within the intra-laminate galleries of LDH, charge-balancing anions determined the channel size, water absorption capacity and electrostatic interactions inside the 2D channels. As a result, hydroxide ion transport was greatly affected by the anionic species present. The organic moieties inside the inter-laminate galleries of LDH conferred hydrogen bonds and covalent linkages at the organic–inorganic interfaces, resulting in a nacre-mimetic structure, leading to the improved mechanical properties of the composite membranes. The synergistic manipulation of composition and interactions within the intra- and inter-laminate galleries endowed the novel anion conductors with both high conductivity (156.3 mS cm−1 at 80 °C) and good mechanical performance (a tensile strength of 48.4 MPa and toughness of 2.09 MJ m−3).

Zirconium-based alloys are widely used for fuel claddings particularly in pressurized water reactor. This study investigates the oxidation characteristics of Zr-4 and Zr-Sn-Nb alloy in steam, oxygen and air atmosphere respectively in temperature range of 650–1250 ℃ by a modified thermo-gravimetric analyzer. The oxidation rate exponents and oxidation kinetic correlations are calculated. The rate transitions of the kinetic oxidation for Zr-Sn-Nb and Zr-4 occur both at 1100 ℃ in steam, both 950 ℃ in air, and 1200 ℃ and 1150 ℃ in oxygen, respectively. The oxidation kinetics of both zirconium alloys in air is faster than in steam and oxygen. The maximum thickness of the oxide layers for both zirconium alloys is reached at 1150 ℃ in steam due to the phase transformation of the zirconium from monoclinic to tetragonal. The oxide layer formed in air is porous, heterogeneous with a multi-layer structure of oxide-nitride-oxide because of the formation and re-oxidation of zirconium nitride in oxygen starvation environment. The oxidation resistance of the zirconium alloy is related to the integrity and compactness of the oxide layer. Gas diffusion through the imperfection in the oxide scale may accelerate subsequent oxidation.

In this study, a well-designed polysulfone with dense phenyl groups surrounding its backbone (designated as P(ES1-co-ES2)) was synthesized and then modified with abundant quaternary ammoniums (QA). The QA functionalized P(ES1-co-ES2) was added to QA functionalized poly (ether ether ketone) with N,N,N',N'-tetramethyl-1,6-hexanediamine (TMHDA) as crosslinking reagent to fabricate anion exchange imembranes (AEM). The incorporation of abundant QA groups substantially increased the ion exchange capacity of the blend membranes. Meanwhile, the densely QA functionalized P(ES1-co-ES2) acted as “hydroxide ion wires” in blend membranes, constructing efficient ion channels for high-speed ion transfer. High hydroxide conductivity up to 215.4 mS cm−1 at 90 °C and the maximum power density of single fuel cell up to 137.2 mW cm−2 at 60 °C were thus achieved. In addition, the strong covalent interaction caused by TMHDA led to significantly enhanced physical stability (anti-swelling, tensile strength and elongation etc.), while the steric hindrance by the long aliphatic chain of TMHDA enhanced the chemical stability of the blend membranes. This study presents a novel AEM with simultaneously enhanced hydroxide conductivity, physical and chemical stabilities.

A novel approach to in-situ synthesize and encapsulate phosphotungstic acid into the cavity of MIL-101(Cr) using Na2WO4·2H2O and Na2HPO4 as precursors is presented to increase the acid loading content (31.4 wt.%). The phosphotungstic acid-encapsulating MIL-101(Cr) (HPW@MIL101) is introduced in sulfonated poly(ether ether ketone) (SPEEK) to prepare SPEEK/HPW@MIL101 nanohybrid membranes for PEMFC applications. Due to the introduction of HPW@MIL101, proton-conducting nanochannels are constructed both in the cavity of MIL101 and at the interface between HPW@MIL101 and SPEEK. Meanwhile, due to the hygroscopicity of phosphotungstic acid, the membrane dehydration at elevated temperatures is alleviated. The proton conductivity at low relative humidity is remarkably enhanced. The nanohybrid membrane with 9 wt.% HPW@MIL101 exhibits proton conductivity of 272 mS cm−1 at 65 °C, 100% RH and 6.51 mS cm−1 at 60 °C, 40% RH, which are 45.5% and 7.25 times higher than those of pristine SPEEK membrane (187 mS cm−1 and 0.898 mS cm−1), respectively. The single H2/O2 fuel cell with SPEEK/HPW@MIL-9 membrane acquires the power density of 383 mW cm−2 at 100% RH, which is 27.2% higher than that of pristine SPEEK membrane. The peak power density of SPEEK/HPW@MIL-9 membrane at 55% RH is 2.97 times higher than that of pristine SPEEK membrane (79 mW/cm2).

Chloromethylated mesoporous silica nanoparticles (CM MSN) were synthesized through co-condensation of tetraethoxysilane and (chloro) phenyltrimethoxysilane precursors using hexadecyl trimethyl ammonium bromide as template. With the addition of the particles into chloromethylated poly (ether ether ketone) (PEEK), the hybrid membranes were prepared by a solution-casting method after complete quaternization of the casting solution. The successful synthesis of the particles was verified by transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy while the effect of CM MSN incorporation on membrane performance including thermal stability, mechanical strength and hydroxide conductivity was investigated by thermal gravimetric analysis, electronic stretching machine, alternating-current impedance and so on. Owing to the large pore volume and high surface area of the particles, the hybrid membranes exhibited enhanced hydroxide conductivity (88.7% increase at 60 °C, 100% RH with 5.0 wt% filling content) due to an increase in ion concentration and optimization of the channel morphology. Besides, higher mechanical strength, thermal and dimensional stability of hybrid membranes were obtained compared with those of the imidazolium PEEK membrane.

With well-defined channels and tunable functionality, metal-organic frameworks (MOFs) have inspired the design of a new class of ion-conductive compounds. In contrast to the extensive studies on proton-conductive MOFs and related membranes attractive for fuel cells, rare reports focus on MOFs in preparation of anion exchange membranes. In this study, chloromethylated MIL-101(Cr) was prepared and incorporated into chloromethylated poly (ether ether ketone) (PEEK) as a multifunctional filler to prepare imidazolium PEEK/imidazolium MIL-101(Cr) (ImPEEK/ImMIL-101(Cr)) anion exchange membrane after synchronous quaternization. The successful synthesis and chloromethylation of MIL-101(Cr) were verified by transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy while the enhanced performance of composite membranes in hydroxide conductivity, mechanical strength and dimensional stability were evaluated by alternating-current impedance, electronic stretching machine and measurement of swelling ratio. Specifically, incorporating 5.0 wt% ImMIL-101(Cr) afforded a 71.4% increase in hydroxide conductivity at 20 °C, 100% RH. Besides, the composite membranes exhibited enhanced dimensional stability and mechanical strength due to the rigid framework of ImMIL-101(Cr). At room temperature and the ImMIL-101(Cr) content of 10 wt%, the swelling ratio of the ImPEEK/ImMIL-101(Cr) was 70.04% lower while the tensile strength was 47.5% higher than that of the pure membrane.

Simultaneous manipulation of vehicle-type and Grotthuss-type proton conduction within proton exchange membranes (PEMs) to induce satisfactory proton conductivity is crucial and challenging for promising environmentally friendly devices such as PEM fuel cells. In this study, a facile one-pot biomimetic mineralization approach is proposed for the construction of binary SiO2–TiO2 nanoparticles with a tunable ratio of silica to titania. Then the nanoparticles are functionalized by acid–base pairs and introduced into a Nafion matrix to fabricate novel hybrid membranes. The interaction between functional groups on SiO2–TiO2 binary nanoparticles and the polymer endows the hybrid membrane with good interfacial compatibility and enhanced dimensional stability. The incorporation of acid–base pairs reduces the activation energy for proton transfer; as a result, the hybrid membrane exhibits the highest proton conductivity of 1.37 × 10−2 S cm−1 at 26.1% RH and 80 °C, which is two orders of magnitude higher than that of recast Nafion. Compared with recast Nafion, a 51.3% increase in maximum power density is achieved for the Nafion/Si1–Ti2-160 hybrid membrane at 60 °C.

Biological membranes possess hierarchical channels and thus exhibit ultrahigh permselectivity for molecules and ions. Intrigued by the delicate structure and transport mechanisms in biochannels, polymer composite membranes with selective transport channels are successfully fabricated for diverse energy- and environment-related applications. This tutorial review aims to present the latest progress in the design and construction of selective molecule/ion transport channels within polymer composite membranes with emphasis on the regulation of the physical and chemical microenvironments of these channels. The concluding remarks are presented with a tentative perspective on the future research and development of highly efficient channel-facilitated molecule/ion transport across polymer composite membranes.

peer-reviewed Developing new materials for the fabrication of proton exchange membranes (PEMs) for fuel cells is of great significance. Herein, a series of highly crystalline, porous, and stable new covalent organic frameworks (COFs) have been developed by a stepwise synthesis strategy. The synthesized COFs exhibit high hydrophilicity and excellent stability in strong acid or base (e.g., 12 m NaOH or HCl) and boiling water. These features make them ideal platforms for proton conduction applications. Upon loading with H3PO4, the COFs (H3PO4@COFs) realize an ultrahigh proton conductivity of 1.13×10−1 S cm−1, the highest among all COF materials, and maintain high proton conductivity across a wide relative humidity (40–100 %) and temperature range (20–80 °C). Furthermore, membrane electrode assemblies were fabricated using H3PO4@COFs as the solid electrolyte membrane for proton exchange resulting in a maximum power density of 81 mW cm−2 and a maximum current density of 456 mA cm−2, which exceeds all previously reported COF materials.

Graphene oxide (GO) membranes with 2D interlaminar channels have triggered intensive interest as ion conductors. Incorporating abundant ion-conducting sites into GO interlayers is recognized as an effective strategy to facilitate ion conduction. Herein, we designed supramolecular compounds

Graphene oxide (GO) membrane, bearing well-aligned interlayer nanochannels and well-defined physicochemical properties, promises fast proton transport. However, the deficiency of proton donor groups on the basal plane of GO and weak interlamellar interactions between the adjacent nanosheets often cause low proton conduction capability and poor water stability. Herein, we incorporate sulfonated graphene quantum dots (SGQD) into GO membrane to solve the above dilemma

Coating an ultrathin crosslinked graphene oxide film onto a Nafion support enables the tradeoff effect to be successfully overcome by the resulting composite membrane: 93% decrease of methanol permeability while retaining the high proton conductivity of Nafion, owing to the synergistic modulation of methanol-transport and proton-transport channels within the graphene oxide film.

The emergence of all-organic frameworks is of fundamental significance, and designing such structures for anion conduction holds great promise in energy conversion and storage applications. Herein, inspired by the efficient anion transport within organisms, a de novo design of covalent organic frameworks (COFs) toward ultrafast anion transport is demonstrated. A phase-transfer polymerization process is developed to acquire dense and ordered alignment of quaternary ammonium-functionalized side chains along the channels within the frameworks. The resultant self-standing COFs membranes exhibit one of the highest hydroxide conductivities (212 mS cm-1 at 80 °C) among the reported anion exchange membranes. Meanwhile, it is found that shorter, more hydrophilic side chains are favorable for anion conduction. The present work highlights the prospects of all-organic framework materials as the platform building blocks in designing ion exchange membranes and ion sieving membranes.

Graphene oxide (GO) membrane, possessing well-aligned laminar interlayer channels and oxygen bearing groups, offers great potentials as proton conductor in fuel cells. Yet, the scarcity and non-uniform distribution of proton conducting sites in the interlayer channels often lead to low conductivity and hinder the use of GO membranes for proton conduction. Single strand deoxyribonucleic acid (ssDNA) molecules bear abundant phosphate and amidogen groups which can act as proton conducting sites. The sequentially arranged phosphate and amidogen groups are in a linear molecule chain, which accords with the ideal arrangement of proton conducting sites. Herein, we intercalated ssDNA into GO interlayer channels via a pre-assembly process to create high-efficient proton conducting channels. GO nanosheets offer well-aligned 2D physical channels and ssDNA provides large amount of sequentially arranged proton conducting sites, which synergistically enhance proton conduction. The DNA@GO-3 membrane shows a proton conductivity of 564.8 mS cm−1 at 80 °C and 98% RH, which is 4.4-fold higher than that of pristine GO membrane and among the highest of the reported GO-based membranes. The H2/O2 single fuel cell performance is improved by nearly 3 folds in terms of maximum power density.

The design of new types of proton-conductive materials with high proton conductivity has sparked tremendous interest. Covalent organic framework (COF), a new category of porous crystalline materials possessing well-defined porosity and tunable functionality, holds great potential as next-generation proton conductors. Here, triazole COF loaded with phosphotungstic acid (HPW@COF) has been incorporated into sulfonated poly(ether ether ketone) (SPEEK) matrix to fabricate SPEEK/HPW@COF composite membranes. The one-dimensional channels of COF lined with protonated triazole (triazolium cations) by hydroscopic HPW and neutral triazole as well as counter anions (PO40W123−) could act as proton-donors and -acceptors forming interconnected hydrogen-bonding networks, thus greatly facilitating proton conduction via Grotthuss-type mechanism particularly under low RH. Accordingly, SPEEK/HPW@COF displayed 35.5 times higher proton conductivity than the plain SPEEK at 65 °C, 40% RH. Moreover, the proton conductivity of SPEEK/HPW@COF remained constant during soaking in water for 15 days, indicating the excellent immobilization of HPW due to the electrostatic interaction between basic nitrogen sites and HPW as well as the confinement effect of microporous COF channels. These results demonstrated that N-heterocycles functionalized COFs gave great promise as effective hosts to encapsulate proton carriers.

Proton exchange membranes (PEMs) have triggered growing attention in energy-related applications due to their fundamental and technological significance. In this work, silica-based nanoscale ionic materials (NIMs-SiO2) were synthesized and incorporated into sulfonated poly (ether-ether-ketone) (SPEEK) to prepare nanocomposite membranes. NIMs-SiO2 could not only provide extra proton transfer sites, but also enhanced the hydrophilicity of the membranes, leading to decrease of the activation energy. The nano-scale size (7 nm) and the functional groups of the NIMs-SiO2 lead to good interfacial adhesion with SPEEK, improving the mechanical properties of the membranes. Consequently, SPEEK/NIMs-SiO2(5) exhibited the highest proton conductivity and peak power density, which were 1.92 and 1.51 folds higher than the pristine SPEEK membranes, respectively. The results showed the nanocomposite membranes had potential as alternative proton exchange membranes for corresponding devices.

Combining two facile methods, spinodal blending and self-crosslinking by chloromethyl groups are jointly utilized in fabricating alkaline anion exchange membranes (AEMs). Highly and moderately chloromethylated poly(ether ether ketone)s and sub-equimolar (to chloromethyl) amounts of 1-methylimidazole are mixed and reacted to form blend AEMs. Nanoscale bi-continuous phase separated morphologies are obtained due to spinodal decomposition. Subsequent heat treatment triggers self-crosslinking of the AEMs arising from residual chloromethyl groups in membranes. Compared with unblended and uncrosslinked AEMs having similar ion exchange capacity (IEC), the ion conductivity of the present AEMs is increased by 45.4% in water and 113% in 95% RH at 60 °C. Dimensional and alkaline stabilities of AEMs are also enhanced by the self-crosslinking, i.e., the swelling ratio decreases by 50.3% at 60 °C and the residual conductivity increases by 26.3% after alkaline treatment in 1 M NaOH at 60 °C. Interestingly, individual spinodal blending or self-crosslinking are found ineffective in overcoming the trade-off between AEM conductivity and stability, while a combination of both methods leads to a simultaneous improvement in conductivity and membrane stability.

The creation of interconnected ionic nanoaggregates within solid electrolytes is a crucial yet challenging task for fabricating high-performance alkaline fuel cells. Herein, we present a facile and generic approach to embedding ionic nanoaggregates via pre-designed hybrid core-shell nanoarchitecture within nonionic polymer membranes: i) synthesizing core-shell nanoparticles composed of SiO2/densely quaternary ammonium functionalized polystyrene. Due to the spatial confinement effect of the SiO2 “core”, the abundant hydroxide-conducting groups are locally aggregated in the functionalized polystyrene “shell”, forming ionic nanoaggregates bearing intrinsic continuous ion channels; ii) Embedding these ionic nanoaggregates (20-70 wt%) into polysulfone matrix to construct interconnected hydroxide-conducting channels. The chemical composition, physical morphology, amount and distribution of the ionic nanoaggregates are facilely regulated, leading to highly connected ion channels with high effective ion mobility ...

Nafion, as a state-of-the-art solid electrolyte for proton exchange membrane fuel cells (PEMFCs), suffers from drastic decline in proton conductivity with decreasing humidity, which significantly restricts the efficient and stable operation of the fuel cell system. In this study, the proton conductivity of Nafion at low relative humidity (RH) was remarkably enhanced by incorporating multifunctional graphene oxide (GO) nanosheets as multifunctional fillers. Through surface-initiated atom transfer radical polymerization of sulfopropyl methacrylate (SPM) and poly(ethylene glycol) methyl ether methacrylate, the copolymer-grafted GO was synthesized and incorporated into the Nafion matrix, generating efficient paths at the Nafion-GO interface for proton conduction. The Lewis basic oxygen atoms of ethylene oxide (EO) units and sulfonated acid groups of SPM monomers served as additional proton binding and release sites to facilitate the proton hopping through the membrane. Meanwhile, the hygroscopic EO units enhanced the water retention property of the composite membrane, conferring a dramatic increase in proton conductivity under low humidity. With 1 wt % filler loading, the composite membrane displayed the highest proton conductivity of 2.98 × 10

The objective of this study is to exploit the one-dimension structure and good proton conduction of phosphorylated silica nanotubes for high proton conductivity of proton exchange membrane (PEM). Three types of poly(vinylphosphonic acid-co-divinylbenzene)/silica nanotubes with different aspect ratios are synthesized and incorporated into the sulfonated poly(ether ether ketone) (SPEEK) matrix to prepare composite membranes. The poly(vinylphosphonic acid) segments in the nanotubes could construct facile proton-conduction pathway along this one-dimensional nanostructure. The nanotubes with high aspect ratio exhibit more pronounced effect in elevating the proton conductivity of membranes, revealing the importance of continuity of conduction pathway on proton transport. The membrane incorporated with the nanotubes of the largest aspect ratio of 45.9 exhibits the highest proton conductivity of 0.1032 S cm−1 at 30 °C, 100% RH, which was 84% higher than that of SPEEK control membrane. Moreover, the nanotubes can reduce the methanol permeability, and improve mechanical stability of the membranes.

The catalytic synthesis of ethylbenzene by alkylation of benzene with diethyl carbonate was carried out over HZSM-5 with Si/Al ratios from 50 to 250. The catalysts were characterized by XRD, SEM, 29Si and 27Al MAS-NMR, NH3-TPD and pyridine IR techniques. HZSM-5 with a Si/Al ratio of 200 exhibited the best benzene conversion and ethylbenzene selectivity because of its ideal acid strength. Strongly acidic sites may lead to an excessive decomposition of diethyl carbonate. The effects of temperature, feed ratio, WHSV and time-on-stream on catalytic activity and product selectivity were studied, and a possible mechanism is presented.