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In order to realise high ionic conductivity and improved chemical stability, a series of anion exchange membranes (AEMs) with semi-interpenetrating polymer network (sIPN) has been prepared via the incorporation of crosslinked poly(biphenyl N-methylpiperidine) (PBP) and spirobisindane-based intrinsically microporous poly(ether ketone) (PEK-SBI). The formation of phase separated structures as a result of the incompatibility between the hydrophilic PBP network and the hydrophobic PEK-SBI segment, has successfully promoted the hydroxide ion conductivity of AEMs. A swelling ratio (SR) as low as 12.2 % at 80 °C was recorded for the sIPN containing hydrophobic PEK-SBI as the linear polymer and crosslinked structure with a mass ratio of PBP to PEK-SBI of 90/10 (sIPN-90/10

Poly(aryl piperidinium) (PAP) anion exchange membranes (AEMs) furnish an important avenue for the commercialization of anion exchange membrane fuel cells (AEMFCs), but their ionic conductivity and alkali resistance still need to be improved. Here, we report the synthesis of PAP AEMs with a branched structure by the acid-catalyzed reaction and compare them with the main-chain AEMs. The experimental results show that the branched AEMs have higher OH

A kind of anion exchange membranes (AEMs) with C C bond end-group crosslinked structure was synthesized successfully. Unlike the traditional aliphatic AEMs, the AEMs were prepared in this work by a strategy to realize the C C bond thermal end-group crosslinking reaction, exhibiting an obvious microphase separation structure and a suitable dimensional stability. The well-defined ion channels constructed in the AEMs guarantee the fast OH− conduction, as confirmed via physical and chemical characterization. The conductivity was dramatically enhanced due to the effective ion channels and increased ion exchange capacity. Among the as-prepared AEMs, the PHFB-VBC-DQ-80% AEM has a conductivity of 135.80 mS cm−1 at 80 °C. The single cell based on PHFB-VBC-DQ-80% can achieve a power density of 141.7 mW cm−2 at a current density of 260 mA cm−2 at 80 °C. The AEMs show good thermal stability verified by a thermogravimetric analyzer (TGA). Furthermore, the ionic conductivity of PHFB-VBC-DQ-80% only decreased by 7.1% after being soaked in a 2 M NaOH solution at 80 °C for 500 h.

Simple sol-gel method and microwave method were used to prepare two-dimensional Pd1Snx/TiO2-GO catalyst with high catalytic activity and strong resistance to CO poisoning. The morphology and structure of Pd1Snx/TiO2-GO catalyst were characterized by TEM, XRD and XPS. It was shown that the spindle TiO2 are uniformly fixed on the GO sheets and can still maintain the morphology after Pd and Sn nanoparticles loading. At the same time, Pd and Sn NPs were both uniformly anchored on the surface of the composite carrier according to EDS element mapping. The two-dimensional composite support TiO2-GO formed by the spindle-shaped TiO2 grown uniformly in-situ on GO helps to achieve uniform anchoring of metal nanoparticles. By introducing the second metal Sn, the electronic structure of Pd can be modified to provide more oxygen-containing groups, which leads to a more complete ethanol oxidation process. Through electrochemical tests, it can be found that Pd1Snx/TiO2-GO had excellent catalytic activity, anti-poisoning ability and long-term stability for ethanol electrooxidation in alkaline environment. The residual current density of Pd1Sn0.40/TiO2-GO is 7 times than that of PdSn/C (JM). Especially, the residual current density of Pd1Sn0.40/TiO2-GO catalyst only decreased by 16.7% after continuously scanned by cyclic voltammetry for 8 times.

Intercalated laminar membrane with controllable interlayer spacing (d-spacing) is one of the most effective membranes for fast molecule separation. In this work, we demonstrate a versatile strategy to create nanosheet-templated water channels in laminar graphene oxide (GO) membranes. The 1.2 nm-thick nickel hydroxide nanosheets as sacrificed intercalators provide a chance to control the d-spacing and simultaneously retain hydrophilicity. The resultant membranes have controllable channels and exhibit over 6 times higher water permeance than the unintercalated membrane. The 880 nm-thick nanosheet-templated GO (NST-GO) membrane has accurate d-spacing of about 1.14 nm and shows high water permeance of 120.3 L m−2 h−1 bar−1 and good molecule separation property, reflecting in high rejection for larger dyes (90.1% for erythrosine b (EB)), while low rejection for smaller dyes (58.3% for methylene blue (MB)). Furthermore, this strategy of intercalating and sacrificing nanosheets has higher potential than traditional intercalation in controlling d-spacing of laminar membranes.

Anion exchange membranes (AEMs) with robust alkaline stability and high ionic conductivity are imminently required for the promising electrochemical energy conversion devices – fuel cells. Herein, a series of novel crosslinked AEMs with hydrophobic fluorine-based polymer backbones bearing special functional sites and hydrophilic long flexible multi-cation side chains are prepared. Morphology observation and ion transport analysis confirm the existence of distinct microphase separation and efficient ion-conducting channels within the membranes resulting from the inherent chemical structure. A highest ionic conductivity of 136.27 mS cm−1 can be achieved by TQ-PDBA-70% (IEC = 2.16 meq. g−1) at 80 °C. Meanwhile, the prepared TQ-PDBA-X AEMs exhibit a desirable swelling ratio ( 22.8 MPa). It is worth noting that the retained ionic conductivity of the TQ-PDBA-70% AEM is 98.14%, 95.50%, 77.90%, 72.02% and 58.15% after being immersed in 1, 2, 4, 8 and 10 M KOH at 80 °C for 1000 h, respectively. Chemical structure change of the TQ-PDBA-70% AEM before and after the alkaline stability test is negligible, as revealed by FT-IR. Moreover, TQ-PDBA-70% has high ionic exchange capacity (IEC) retention and maintains good mechanical properties. A single cell assembled with TQ-PDBA-70% has a maximum power density of 158.8 mW cm−2 under a current density of 360 mA cm−2. These results suggest that this type of structure opens a new strategy for developing high performance AEMs.

Pervaporation is a promising membrane technology for separation of aqueous organic solution particularly azeotrope and close-boiling point compounds. However, most of pervaporation membranes are based on hydrophilic polymers that suffer decline of separation performance due to their swelling in aqueous solution. Here we present a copolymer synthetic strategy for preparation of hydrophobic polymer pervaporation membrane with hierarchical porosity via uniting both rigid and flexible segments. The synthesized membrane has well-defined micropores and high free volume faction of 8.03% with cavity size of 0.476 nm, and demonstrate exceptional performance with high permeability and selectivity for dehydration of alcohols. In the pervaporation of ethanol-water azeotrope, the membrane displays the high permeabtion flux of 74.6 μm kg m−2 h−1 and water selectivity of 34 (separation factor of 732) at 30 °C. The developed strategy has excellent potential for synthesizing copolymers for high-efficient pervaporation membranes.

Anion exchange membranes (AEMs) of side-chain polymers have attracted growing attention recently in the fuel cells. However, their dimensional stability and alkali resistance still not meet the requirements for industrial application of fuel cells. Herein we demonstrate a facile approach to prepare the side-chain-type polymer AEMs with high performances via introducing both hydrophobic and hydrophilic side chains onto the backbone. Grafting hydrophobic side chain into the backbone favor to construct a well-defined micro-phase separation structure and fabricate fast ion transporting pathway. The resulting polyethersulfone (PES) based AEMs display a high hydroxide conductivity and good physicochemical stability. Impressively, the PES-8C0.15-QA0.85 AEM has a 54.3% increase in the hydroxide conductivity and a 45% decrease in the swelling ratio (SR) by introducing a small amount of hydrophobic side chain. Furthermore, the AEMs show good mechanical properties, alkaline tolerance and oxidative stability. The loss of ionic exchange capacity and hydroxide conductivity is less than 15% after alkaline treatment (1 M KOH, 60 °C, 480 h). This approach will be favorable to exploit practical AEMs for fuel cells.

Anion exchange membranes (AEMs) are a crucial constituent for alkaline fuel cells. As the core component of fuel cells, the low performance AEMs restrict the development and application of the fuel cells. Herein, the trade-off between the OH– conductivity and dimensional stability was solved by constructing AEMs with adequate OH– conductivity and satisfactory alkali resistance using Troger’s base (TB) poly (crown ether)s (PCEs) as the main chain, the embedded quaternary ammonium (QA) and Na+-functionalized crown ether units as the cationic group. Crown ether is an electron donator, and can capture Na+ to form Na+-functionalized crown ether units to conveniently transfer OH– and significantly promote the alkaline stability of the AEMs. The influence of the Na+-functionalized crown ether units on the performance of AEMs was studied in detail. The PCEs based AEMs show an obvious hydrophobic-hydrophilic microphase separation. These features make them ideal platforms for the OH– conduction applications. As expected, the as-prepared PCEs-QA-100% (100% is the degree of cross-linking) AEM with an ionic exchange capacity (IEC) of 2.07 meq g−1 has a high OH– conductivity of 159 mS cm−1 at 80 °C. Furthermore, the membrane electrode assemblies fabricated using the PCEs-QA-100% AEM possess a maximum power density of 291 mW cm−2 under the current density of 500 mA cm−2.

In this work, simple chemical reduction method is used to prepare Pd–Sn nanocatalysts supported on carbon for ethanol electro-oxidation in alkaline environment using ethylene glycol as reductant. The composition, structure and morphologies of PdSn/f-C catalysts are investigated by X-ray diffraction, X-ray photoelectron spectroscopy, energy dispersive X-ray and transmission electron microscopy. The electro-chemical activity and durability of as-obtained PdSn/f-C nanocatalysts are investigated and determined by cyclic voltammetry and Chronoamperometric measurements. The obtained results demonstrate that as prepared PdSn/f-C nanocatalysts have uniform dispersion and small particle size. In addition to, the as prepared PdSn/f-C nanocatalysts have higher electro-chemical activity and better stability toward EOR in alkaline environment than those of Pd/f-C and commercial Pd/C (JM) nanocatalysts. Specifically, the electro-catalytic activity of Pd 1.5 Sn/f-C nanocatalyst (3413.3 mA mg Pd − 1 ) is almost 8.6 times higher than Pd/C (JM) nanocatalyst (355.2 mA mg Pd − 1 ), which has competitive power among reported Pd–Sn catalysts. These results indicate that the uniform carbon supported PdSn nanostructure are promising electrocatalysts for direct ethanol fuel cells.

Mixed matrix membranes (MMMs) prepared by blending nanocomposites and organic polymers are attractive for producing new materials with improved characteristics such as good hydrophobicity, excellent permeate flux and high separation factor in pervaporation (PV). In order to overcome the aggregation of inorganic nanofillers in membrane and the leakage of inorganic nanoparticles from hybrid membrane in separation process, the polymers of intrinsic microporosity (PIMs) materials with unique properties were successfully synthesized and employed as organic microporous fillers owning good affinity with polymer matrix. The PIM-1/polydimethylsiloxane (PDMS) hybrid pervaporation membranes were then fabricated by mutual combination of the rigidity of PIM-1 and the flexibility of PDMS. The organophilic PIM materials were discovered to provide definite improvements in enhancing the interfacial compatibility and solvent resistance ability to achieve defect-free membrane. Various techniques including FTIR, SEM, EDS, NMR, GPC, contact angle goniometry, N2 absorption/desorption, pervaporation measurements and swelling tests were used to characterize and evaluate the properties of PIMs and membranes. Compared with the pristine PDMS membrane, the prepared PIM-1/PDMS pervaporation membrane exhibited superior permeate flux of 1425.3 g m−2 h−1 and competitive separation factor of 30.7 in the separation of n-butanol–water system under a very low concentration of 1.0 wt%. Moreover, the membrane displayed excellent stability and integrity even over 240 hour’s long-term continuous operation, which showed great potential for industrial application.

Magnetic iron-titanium binary oxide as an effective adsorbent for arsenic contaminant is a challenge primarily because of their bulk structure and agglomeration effect. Herein, a novel and uniform sandwich-like magnetic Fe3O4@TiO2 sheets were synthesized by utilizing a facile strategy involving amorphous-to-crystalline transformation and reduction in H2, to achieve dispersed anatase TiO2 nanoparticles with a small size of ∼8 nm anchored on Fe3O4 sheets. The resultant Fe3O4@TiO2 sheets nanocomposite possessing a high specific surface area of ∼89.4 m2 g−1 and available magnetic susceptibility of ∼20.0 emu g−1, significantly enhanced the photocatalytic oxidation property of arsenite and considerable adsorption capability for arsenic removal. The adsorption capacities of As(V) and As(III) with UV-assisted from adsorption experimental results were 36.36 and 30.96 mg g−1, respectively, while the residual concentrations for both As(V) and As(III) were lower than the strict limit of 10 μg L−1. Adsorption equilibriums were almost reached within 45 min. In addition, the adsorbent exhibited excellent stability over a broad pH range of 3–9 and still maintained great removal efficiency after five time regeneration cycles. Furthermore, except for silicate and phosphate, the extremely weak inhibiting influences of common co-existing ions in arsenic removal process, demonstrated that the developed magnetic Fe3O4@TiO2 sheets with unique nanostructure could be a promising efficient adsorbent for arsenic removal.

The excellent catalyst need to meet low cost, long-time stability and high electrocatalytic activity in direct ethanol fuel cells (DEFC). Here, carbon nanotube-supported Pd-based (Pd/CNT, PdSn/CNT, PdNi/CNT and PdSnNi/CNT) catalysts were synthesized by microwave-assisted polyols and in-situ reduction. Compared with commercial Pd/C (JM), the as-prepared Pd-based catalysts have higher electrocatalytic activity and outstanding long-time durability toward ethanol electro-oxidation reaction in alkaline media. The enhanced electrocatalytic activity of Pd-based catalysts are owning to high electrochemically active surface area (ECSA) and modified electronic structure of Pd. After chronoamperometric test, the current densities of Pd-based catalysts can be reactivated by simple cycle potential scan in 1 M NaOH, which indicated that all of them have excellent resistance to CO poisoning.

Self-recoverable Pd–Ru/TiO2 nanocatalysts have been prepared by electrochemical stripping of Pd–Ru/TiO2 precursors. For the ethanol oxidation reaction (EOR), these Pd–Ru/TiO2 nanocatalysts are used as an anode catalyst. The characterization of catalysts via chronoamperometry has been repeated 15 times. After 15 stability tests, the Pd1Ru0.69/TiO2 nanocatalysts still achieve a factor of 9.4 enhancement at the residual current density (309.42 mA mgPd−1) for the EOR over commercial Pd/C catalysts (33.01 mA mgPd−1). From the 5th to 15th test, when each 10 000 s stability test is performed in a fresh ethanol electrolyte, the initial and residual current density of the catalysts could recover to the original or even better value in a few hours before performing another 10 000 s stability test. Herein, these Pd–Ru/TiO2 nanocatalysts with ultrastability towards ethanol electrooxidation are self-recoverable. Density functional theory calculations reveal that the introduction of oxophilic metal Ru and a TiO2 support into Pd-based catalysts and the synergistic effects between Ru and TiO2 have led to the ultrastability towards the EOR. The introduction of oxophilic metal Ru and a TiO2 support into catalysts can reduce the adsorption energy of OHads on the Pd–Ru/TiO2 nanocatalysts, and it will inhibit the COads produced and adsorbed on the Pd surface.

To explore the alkaline stability of cationic groups, several investigations have been reported via small molecule model compounds, theoretical calculations or grafting cations to the benzylic positions of the polymer backbones. In this work, anion exchange membranes (AEMs) with various head groups of trimethylammonium (TMA), 1-methylpyrrolidinium (MPY), 1-methylpiperidinium (MPRD), 1-methylimidazolium (Im1) and 1,2-dimethylimidazolium (Im1,2)) flexibly linked to poly(ether sulfone) (PES) backbones are prepared to explore the effect of pendent functional groups. The AEMs tethering MPRD groups are found to exhibit the highest Br− conductivity of 60.4 ± 2.1 mS cm−1 at 80 °C. PES-MPY exhibits the best relative stability and maintains 90.7% and 83.1% of the original ionic exchange capacity (IEC) and conductivity, respectively, after immersed into 2 M NaOH at 60 °C for 672 h. Meanwhile, the alkaline stability is in the order of PES-MPY > PES-MPRD > PES-TMA > PES-Im1,2 > PES-Im1. The maximum power density of a H2/O2 fuel cell using PES-MPRD (109.0 mW cm−2) and PES-MPY (106.5 mW cm−2) is larger than that using PES-Im1 (65.1 mW cm−2). The results provide a guidance for designing high-performance AEMs.

A novel two-dimensional (2D) zeolitic imidazolate framework-graphene oxide hybrid nanocomposite (ZIF-L@GO) is designed as an inorganic filler in sulfonated poly(ether ether ketone) (SPEEK). ZIF-L with unique leaf-like morphology is grown in-situ on the GO sheet in aqueous media at room temperature. The terminal imidazole linker in ZIF-L@GO and the –SO3H in SPEEK can form acid-base pairs in the membrane interface to produce low energy proton conduction highway. Benefiting from the unique structural advantage, the hybrid SP-ZIF-L@GO membranes displayed promoted physicochemical and electrochemical performances over the pure SPEEK. The SP-ZIF-L@GO-5 achieved a proton conductivity of 0.265 and 0.0364 S cm−1 at 70 °C-100% RH and 90 °C-40% RH, 1.76- and 6.24-fold higher than pure SPEEK, respectively. Meanwhile, a single cell based on SP-ZIF-L@GO-5 had an output power up to 652.82 mW cm−2 at 60 °C, 1.45 times higher than the pure SPEEK. In addition, the durability test was performed by holding open circuit voltage (OCV) for 24 h. The SP-ZIF-L@GO-5 provided better long-term stability than the pure SPEEK. These superior performance suggests a promising application in PEMFC.

The development of anion exchange membranes (AEMs) is hindered by the trade-off of ionic conductivity, alkaline stability, and mechanical properties. Troger's base polymers (Tb-polymers) are recognized as promising membrane materials to overcome these obstacles. Herein, the AEMs made from Tb-poly(crown ether)s (Tb-PCEs) show good comprehensive performance. The influence of crown ether on the conductivity and alkaline stability of AEMs has been investigated in detail. The formation of hydronium ion-crown ether complexes and an obvious microphase-separated structure formed by the existence of crown ether can enhance the conductivity of the AEMs. The maximum OH- conductivity of 141.5 mS cm-1 is achieved from the Tb-PCEs based AEM (Tb-PCE-1) at 80 °C in ultrapure water. The ion-dipole interaction of the Na+ with crown ether can protect the quaternary ammonium from the attack of OH- to improve the alkaline stability of AEMs. After 675 h of alkaline treatment, the OH- conductivity of Tb-PCE-1 decreases by only 6%. The Tb-PCE-1-based single cell shows a peak power density of 0.202 W cm-2 at 80 °C. The prominent physicochemical properties are attributed to the well-developed microstructure of the Tb-PCEs, as revealed by TEM, AFM, and SAXS observations.

A series of hyperbranched poly(arylene ether ketone) (HBPAEK) anion exchange membranes (AEMs) was synthesized by polycondensation and quaternization using 1-(N′,N′-dimethylamino)−6,12-(N,N,N-trimethylammonium) dodecane bromide. The highest ionic conductivity of the HBPAEK-28-18 AEM with ionic exchange capacity of 2.21 meq g−1 is 122.5 mS cm−1 at 80 °C. The chemical stability of the AEMs was examined upon exposure to a 2 M KOH solution at 80 °C by monitoring the change in ionic conductivity, which decreased from 122.5 to 104.2 mS cm−1 after 500 h. 1H NMR spectra confirmed the chemical stability of the AEM during this period. The hyperbranched structure can not only improve the conductivity, but also increase the chemical stability of the AEMs. The H2/O2 single cell using HBPAEK-28-18 exhibits a maximum power density of 188.6 mW cm−2 under a current density of 450 mA cm−2 at 80 °C. Furthermore, the hyperbranched structure AEMs also exhibited good thermal stability and mechanical property

Polymers of intrinsic microporosity (PIMs) have attracted increasing interest in gas separation membranes due to their high permeability. However, the moderate selectivity limits their wide applications in CO2 separation. Herein we report a facile strategy to improve simultaneously the permeability and CO2 selectivity of PIMs membrane using the prepared PIM-1/graphene oxide (GO) nanosheets mixed matrix membrane. The GO nanosheets improves the hydrophilicity and surface roughness of PIM-1 membrane whereas the uniform assembly of GO nanosheets in the PIM-1 matrix creates the hydrophilic/hydrophobic microphase segregation in the membrane. The as-prepared mixed matrix membrane is also very porous and has a pore size of about 0.78 nm. The combination of these properties significantly contributes to the enhancement of the gas separation performance of PIM-1 membrane, with the resultant membrane exhibiting an exceptionally high CO2 permeability of up to 6169 barrer as well as a high CO2/N2 selectivity of 123.5, which is more than 7 times that of the pure PIM-1 membrane. The developed PIM-1/GO mixed matrix membrane should have a wide application in the CO2 separation.

To enhance the ionic conductivity and mechanical property of the chemically stable aliphatic anion exchange membranes (AEMs), cross-linked poly(vinylbenzyl chloride) AEMs (PVBC-xQ4) bearing long flexible cross-linker chains with multiple quaternary ammonium (QA) head were prepared via a facile one-step process. The AEMs exhibit high conductivity and excellent mechanical property. The cross-linked AEMs excluding any other heteroatomic bond especially the sulfone linkage or ether bond in the backbone have robust alkaline stability, low water uptake, and good dimensional stability. A well-developed hydrophilic/hydrophobic phase separated morphology was observed by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The PVBC-50Q4 membrane with ionic exchange capacity (IEC) of 1.87 mequiv g–1 displays a highest ionic conductivity of 74.3 mS cm–1 at 80 °C. After tested in a 2 M aqueous KOH solution at 80 °C for 1300 h, 88% of the conductivity and 89% of the IEC were remained. Furthermore, ...

Poly(ether ketone)s bearing multication side chains are synthesized via nucleophilic polycondensation, demethylation and the Williamson reaction to prepare high performance anion exchange membranes (AEMs). The introduction of multication side chains is found to promote the formation of hydrophilic/hydrophobic phase segregated morphology, as confirmed by transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). The TQAPEK-0.5 membrane with ionic exchange capacity (IEC) of 1.94 meq g−1 shows the highest hydroxide conductivity of 132.8 mS cm−1 at 80 °C. The first cationic group on the side chain is linked to the backbone via hexyleneoxy groups to render the AEM a good alkaline stability. As a result, TQAPEK-0.5 has only a 22.4% decrease in the conductivity after immersed in a 2 M aqueous KOH solution at 60 °C for 600 h. Besides, the peak power density of a single cell using the TQAPEK-0.5 membrane is observed to be 206 mW cm−2 at a current density of 400 mA cm−2. Furthermore, the as-prepared AEMs also exhibit good mechanical property and thermal stability, and hold promise for application in fuel cells.

The membrane fouling is one of the key issues in ultrafiltration (UF) process because it significantly reduces the membrane permeability and increases industrial cost. The challenge is to improve antifouling ability of UF membranes without compromising their separation performance. Here we report a facile strategy to prepare antifouling UF membranes via grafting of positively charged poly(ethylenimine) (PEI) chains onto brominated tetra-methyl polyethersulfone (TM-PES) membranes. The resultant PEI grafted TM-PES membranes show excellent antifouling ability with sufficient water permeability and outstanding separation performance. Typically, the grafted membrane with the bromination degree (BD) of 73% has not only a high water permeability of 72 L m−2 h−1 bar−1 but also rejections of 96.3% for ferritin and 91.4% for bovine serum albumin (BSA). Specially, the water flux can be recovered nearly 90% after protein fouling. The developed strategy is suitable for preparation of antifouling UF membranes. Moreover, the fabricated membranes have a great potential application in biomacromolecule separation.