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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.

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.

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.

Here we propose a strategy of radical oxidation reaction for the high-efficiency production of graphene oxide (GO). GO plays important roles in the sustainable development of energy and the environment, taking advantages of oxygen-containing functional groups for good dispersibility and assembly. Compared with Hummers' method, electrochemical exfoliation of graphite is considered facile and green, although the oxidation is fairly low. To synthesize GO with better crystallinity and higher oxidation degree, we present a photosynergetic electrochemical method. By using oxalate anions as the intercalation ions and co-reactant, the interfacial concentration of hydroxyl radicals generated during electrochemical exfoliation was promoted, and the oxidation degree was comparable with that of GO prepared by Hummers' method. In addition, the crystallinity was improved with fewer layers and larger size. Moreover, the aniline coassembled GO membrane was selectively permeable to water molecules by the hydrogen-bond interaction, but it was impermeable to Na+, K+, and Mg2+, due to the electrostatic interactions. Thus, it has a prospective application to water desalination and purification. This work opens a novel approach to the direct functionalization of graphene during the electroexfoliation processes and to the subsequent assembly of the functionalized graphene.

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.

To improve the overall performance of anion exchange membranes (AEMs) for fuel cells, a series of composite AEMs was prepared via a facile approach using ionic liquid-functionalized graphene oxide (IL-GO) and imidazolium-functionalized poly (2,6-dimethyl-1,4-phenylene oxide) (ImPPO). The prepared ImPPO/IL-GO-0.5% (0.5% refers to the weight percentage of IL-GO) membranes with an ionic exchange capacity (IEC) of 1.9 meq g−1 achieved a hydroxide conductivity of 78.5 mS cm−1. The high conductivity of ImPPO/IL-GO-0.5% is due to the fact that the ionic cluster size of composite membranes (3.43–3.58 nm) is larger than that of the pristine membrane (3.30 nm). The ionic cluster morphology is confirmed by atomic force microscopy (AFM) and small angle X-ray scattering (SAXS). Moreover, the AEMs retained approximately 70% of their initial hydroxide conductivity after the alkaline stability test in a 2 M aqueous NaOH at 80 °C for 480 h, indicating a good alkaline stability. A single cell using ImPPO/IL-GO-0.5% exhibits a peak power density of 136 mW cm−2 at 60 °C under 100% related humidity, thereby having a great potential for fuel cells.

Poor dispersibility in aqueous media of polymer functionalized one-dimensional materials including carbon nanotubes (CNTs), inorganic nanoparticles and polymer nanofibers is an inherent challenge to their utilization in several applications. Herein, polydopamine grafted CNTs (PDA-CNTs) are rendered dispersible through chemical crosslinking via bioinspired borate chemistry. Nanolayer coatings of polydopamine are deposited on the side walls of CNTs forming aggregates that lead to highly dense and agglomerated PDA-CNTs sediments in aqueous media. Borate crosslinking facilitates the obtainment of a homogeneous dispersion of borate crosslinked PDA-CNTs (B-PDA-CNTs) by forming strong hydrogen bonds in solution and thus permitting the facile fabrication of B-PDA-CNTs membranes with an interconnected nanoporous structure on a macroporous support. The obtained membranes with a controllable thickness are stable and display good ultrafiltration performances of ferritin molecules (>90%) and high water permeability of more than 2.8 × 103 L m−2 h−1 bar−1. The borate chemical crosslinking highlights a versatile approach for the preparation of stable polydopamine coated nanomaterials for wide applications with bio-macromolecules and in nanocomposite materials.

To resolve the excessive swelling and undesirable alkaline stability of densely functionalized type anion exchange membranes (AEMs) and to obtain high performance AEMs, quaternary ammonium-functionalized poly(arylene ether nitrile) (QPAEN) AEMs with dense flexible ionic side chain are prepared via nucleophilic substitution polycondensation, demethylation reaction and Williamson reaction. The densely pendent flexible long side chains with QA groups at the end provide a high conductivity and the introduced strong polar nitrile groups result in lower water uptake, excellent dimensional stability and strong alkali resistance of the AEMs. The QPAEN membrane with IEC of 1.78 meq g−1 exhibits the highest hydroxide conductivity of 116.0 mS cm−1 at 80 °C. The high conductivity is attributed to the well-developed hydrophilic/hydrophobic phase separated morphology that constructs efficient ion conducting pathways in the membranes. High retention of hydroxide conductivity (80.2%) and ionic exchange capacity (IEC) (86.0%) was observed for the QPAEN-0.4 membrane in the degradation test in a 2 M aqueous KOH solution for 480 h. Moreover, the single cell performance of the as-prepared AEMs was greatly enhanced and a high peak power density of 251.3 mW cm−2 at 60 °C was observed.

Polymers of intrinsic microporosity (PIMs) represent a novel class of membrane materials attracting much attention over the past decade. But challenges still exist in the preparation of anion exchange membranes (AEMs) due to their poor solubility and brittleness. Here we present a new strategy to synthesize soluble PIMs for high performance AEMs. By combining merits of two Troger's base units, the synthesized copolymer exhibits good solubility as well as excellent mechanical properties. The copolymer has good solubility in dimethylsulfoxide (DMSO) after little quaternization and thus permits crosslinking with a long-flexible multi-cation agent. The resulting membrane has good dimensional stability (20.8% swelling ratio at 60 °C) and excellent alkaline resistance. Subsequently, this membrane exhibits a high hydroxide conductivity of 103.9 mS cm−1 (80 °C) at a low ion exchange capacity (IEC) of 1.67 meq g−1. Moreover, this membrane achieves a peak power density of 158 mW cm−2 in a single fuel cell at a current density of 330 mA cm−2 at 60 °C. The presented approach is beneficial for developing high performance PIM-based AEMs and highlights the tremendous potential of multi-cation cross-linked Troger's base AEMs for wide application in energy and separation fields.

To enhance the conductivity and alkaline stability of anion exchange membranes (AEMs), partially fluorinated poly(arylene ether) AEMs with functionalized claw-type side chains are prepared. It is found that the integration of a claw-type head into the side chain and a fluorinated moiety into the backbone is favorable for forming a well-defined hydrophilic/hydrophobic phase-separated structure, as confirmed by transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). A highest hydroxide conductivity of 98.19 mS cm−1 is achieved for FPAE-3B-3.0-PD with an ion exchange capacity (IEC) of 1.16 meq. g−1. Besides, the as-prepared AEMs exhibit good dimensional stability, robust mechanical properties and high thermal stability. The FPAE-3B-3.0-PD membrane still maintains about 94% and 93% of its initial IEC and conductivity after being immersed in a 1 M aqueous KOH solution at 80 °C for 600 h. The change in the chemical structure of the AEM before and after the alkaline stability test is negligible, as noted by 1H NMR. Furthermore, the single cell using FPAE-3B-3.0-PD has a highest power density of 156 mW cm−2 at a current density of 350 mA cm−2 at 80 °C.

This work reports the preparation of ternary hollow PdSnNi (H-PdSnNi) catalysts with nanochannels toward the electrooxidation of ethanol in alkaline medium, in which the Pd and Sn nanoparticles grow on the surface of H-Ni microspheres by galvanic replacement method. The reaction is driven by the difference in the equilibrium potential of the Pd/PdCl42−, Sn/Sn2+ and Ni/Ni2+ redox couples. Structural measurements indicate the hollow structure of the H-PdSnNi nanocomposites and the well distribution of nanoparticles. The distinctive Pd NPs and Sn NPs loaded on H-Ni microspheres can efficient prevent Pd NPs from the aggregation and provide a high specific area. Electrochemical tests illustrate that the H-PdSnNi2.5 catalyst has large electrochemically active surface area and prominent activity (1902 A g−1). After the same chronoamperometery test, the residual current density of H-PdSnNi2.5 catalyst remains 1006 A g−1 which is 7.1 times that of Pd/C (JM) (140 A g−1). The superior activity and stability of the H-PdSnNi catalysts toward ethanol electrooxidation are attributed to the hollow structure, the electron effect and bifunctional mechanism due to the addition of Ni and Sn. This work will spur the study of the structure and composition (ternary-metallic) of electrocatalysts toward EOR with superior electrooxidation performance.

With the aim of preparing highly alkaline stable anion-exchange membranes (AEMs) with desirable ionic exchange capacity (IEC) and swelling, a series of crosslinked poly(4-vinylphenol) (PVP)-based membranes was prepared. A facile crosslinking method using bis(hydroxymethyl)-4-cresol (BHMC) as the crosslinker was introduced in the preparation of AEMs to avoid sacrificing specific functional groups such as –OH in the backbone. It is worth mentioning that the whole procedure for membrane preparation was efficient and easy to handle. The as-prepared membranes exhibited pretty low water uptake and swelling by the introduction of a crosslinked structure. Microphase separation to different extents could be observed in the membranes with different degrees of crosslinking via transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). The QAPVP-5% membrane with an ionic exchange capacity (IEC) of 2.12 meq g−1 displayed the highest ionic conductivity of 78 mS cm−1 at 80 °C. Moreover, the all-carbon backbone endowed an excellent alkaline stability of the membranes, and the QAPVP-5% membrane still retained 91.3% of its original conductivity after immersing in a 2 M aqueous KOH solution at 80 °C for 480 h. A peak power density of 122 mW cm−2 was also obtained by a single cell equipped with the QAPVP-5% membrane.

The commercial application of metal oxide composites adsorbent for arsenic removal was limited by some problems, such as low adsorption capacity and difficult recycling. Herein, monodispersed core-shell mesoporous H-Fe3O4@mTiO2 magnetic microspheres adsorbent for efficient arsenic removal was prepared by facile pre-modification of titania precursor and boiling water assisted crystallization treatment. The obtained H-Fe3O4@mTiO2 composite microspheres possessed high-quality core-shell structure with a high specific surface area of 179.98 m2 g−1 and an available magnetic susceptibility of 31.91 emu g−1 which is easy to separate adsorbent from waste water. The batch adsorption experimental results showed that the Langmuir maximum capacities of the obtained H-Fe3O4@mTiO2 for As(V) and As(III) were 7.74 and 18.22 mg g−1, respectively. Particularly, H-Fe3O4@mTiO2 exhibited excellent performance for As(III) removal at a broad pH range of 3–10. Moreover, as-made adsorbent showed excellent stability after 5 regeneration cycles because the preponderant magnetic inner-core can realize fast solid-liquid separation process of adsorbent without any loss.

To investigate the influence of main chain structure on the performance of anion exchange membranes (AEMs), crosslinked naphthalene-based block polymer AEMs are synthesized via nucleophilic polycondensation, Williamson reaction, atom transfer radical polymerization (ATRP) reaction, bromination, and quaternization. With a helical structure, the naphthalene-based triblock backbone can provide the ion channels inside AEMs, further enhance the ionic conductivity and dimensional stability. The crosslinked network of long alkyl chains ensures desirable mechanical properties of AEMs. The prepared NAPEK-PVP-X AEMs have a high alkaline stability, a low swelling ratio and a high ionic conductivity. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) are used to confirm the hydrophilic/hydrophobic microphase separated structure of the AEMs. More developed ion transport channels of naphthalene-based AEMs are shown by molecular dynamics (MD) simulations. A power density peak of 160.73 mW cm−2 is obtained by assembling the NAPEK-PVP-10-Q4 AEM into a single cell operating at 60 °C. The study provides a resource for future work on AEMs.

Clustered alkyl side chains bearing a string of three imidazolium cations with hexyl spacers are grafted to fluorene-based poly (arylene ether sulfone) successfully. Nanostructure is directly configured within the anion exchange membranes (AEMs) via the novel multi-cation side chains. As confirmed by atomic force microscopy (AFM) and small angle X-ray scattering (SAXS), percolating OH – conducting channels with the size of ionic clusters nearly 20 nm endow the trimPES-0.4 membrane with an excellent ion conductivity in excess of 120 mS cm –1 at 80 °C. Because of the self-assembly of ionic groups, water molecules are compartmentalized into the hydrophilic side chain regions instead of backbones, resulting in advantageous over water management. Together with the lengthened hydrophobic segments, TrimPES-0.2 exhibits superior dimensional stability (12.0%, 30 °C) to conventional mono-cation type AEMs. Furthermore, the novel multi-cation TrimPES-0.4 displays a peak power density of 134.4 mW cm –2 at a current density of 280 mA cm –2 . Therefore, these findings suggest that by tuning the distribution of cations, AEMs with well-balanced performance can be made for fuel cell applications.

Alkaline stability is the critical issue for the practical application of anion exchange membranes (AEMs) in fuel cells. The benzyltrimethyl ammonium and backbone with C-O linkages of the traditional AEMs are susceptible to attack by hydroxide ions resulting in poor alkaline stability of the AEMs. Herein, we present the preparation of polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) triblock copolymer via grafting, ketone reduction and quaternization for AEM fuel cell applications. The quaternary ammonium (QA) groups are attached to the SEBS backbone free of C-O linkages via long flexible alkyl spacers, which are responsible for the robust alkaline stability of the AEMs. Thus, the hydroxide conductivity of SEBS-CH 2 -QA-1.5 was only decreased by 7.7% and 13.7% after immersing the membranes into a 1 M aqueous KOH solution at 60 and 90 °C for 360 h, respectively. Furthermore, SEBS-CH 2 -QA-1.5 with IEC of 1.23 meq g −1 exhibits a maximum hydroxide conductivity of 56.4 mS cm −1 at 80 °C and a maximum power density of 94.6 mW cm −2 under a current density of 300 mA cm −2 .

To explore highly conductive and alkaline stable anion exchange membrane (AEM) materials, triblock copolymers bearing alkyl-tethered cycloaliphatic quaternary ammonium-head-groups are prepared via nucleophilic substitution, Friedel-Crafts acylation, ketone reduction and Menshutkin reaction. The designed triblock copolymers composed of quaternized poly(phenylene oxide) segments and poly(ether sulfone) segments are responsible for the microphase separated morphology and well-connected ion domains, as confirmed by transmission electron microscopy. The highest conductivity, up to 105.1 mS cm−1 at 80 °C is achieved for the AEM with ionic exchange capacity (IEC) of 1.81 meq g−1. Furthermore, the AEMs show robust alkaline stability due to the alkyl-tethered cation-head-groups structure. High retention of hydroxide conductivity (88.9%) and IEC (91.2%) is observed for the AEMs via degradation test in a 1 M aqueous KOH solution at 80 °C for 480 h. Based on the AEM with high conductivity, a H2/O2 fuel cell achieves a peak power density of 176.5 mW cm−2 (80 °C) at a current density of 500 mA cm−2.

Covalent crosslinking is considered to be a promising strategy to balance the dimensional stability and conductivity of anion exchange membranes (AEMs). Nevertheless, crosslinking using diamine crosslinkers would introduce hydrophobic alkyl chains into the ionic domain resulting in a significant decline in hydroxide conductivity and crosslinking via catalyst is discouraged. Herein, we presented a strategy for preparing crosslinked AEMs without using catalyst and the crosslinked moiety is away from the ionic domain. The crosslinking was carried out by converting the trifluorovinyl groups into perfluorocyclobutane groups via thermal treatment. The designed side-chain structure is responsible for the obvious hydrophilic/hydrophobic phase separated morphology and interconnected ion conducting channels, as confirmed by atomic force microscopy, transmission electron microscopy and small angle X-ray scattering. The obtained membrane exhibited high dimensional stability and a highest conductivity of 77.1 mS cm −1 at 80 °C. Furthermore, the crosslinked AEMs also had robust mechanical properties, good thermal stability and reasonable alkaline stability.

In this work, bimetallic NiPd hollow nanoporous (H NiPd) catalysts are prepared by in-situ deposition of Pd nanoparticles (Pd NPs) on hollow Ni (H Ni) microspheres. Scanning electron microscope (SEM) and transmission electron microscopy (TEM) reveal the hollow nanoporous essence of H NiPd catalysts. Meanwhile, using high-angle annular dark-field scanning TEM (HAADF-STEM) and elemental mapping, it is found that tiny dendritic-like NiPd nanocomposites attach on the exterior of microspheres. The content of Pd is easily tailored to constitute H NiPd catalysts with different Ni/Pd atomic ratios. Further electrochemical evaluation vindicates that the as-prepared H NiPd catalysts have a good catalytic activity and stability toward ethanol oxidation reaction (EOR) in alkaline medium. Notably, the peak current density of H Ni3.1Pd catalyst and the chronoamperometric current density of H Ni4.6Pd catalyst are 4 and 2 times of Pd/C (JM) catalyst, respectively, which show that H NiPd catalysts hold great potential in application of alkaline direct ethanol fuel cells (DEFCs).

Developing highly active Pd-based nanocatalysts with a well-organized structure is desired for direct alcohol fuel cell commercialization. In this study, room temperature seed mediated growth strategy has been successfully developed to prepare ternary Pd@Cdx-Agy core-shell as advanced novel non-Pt anode nanocatalysts for ethanol oxidation reaction EOR in alkaline electrolyte. The introduction of oxophilic Cd and Ag metals into Pd nanocatalysts can reduce the adsorption energy of OHads on the Pd@Cdx-Agy nanocatalysts and inhibit the COads on the Pd surface. Morphological characterization demonstrates that the as-synthesized Pd@Cdx-Agy nanocatalysts are well-organized core-shell nanostructure with Pd NPs as the core and Cd-Ag alloy as the shell. Moreover, electrochemical results indicate that the Pd@Cd1-Ag1 core-shell catalyst exhibit a remarkable electrochemical activity ( 2995.76 mA mg Pd − 1 ), excellent CO tolerance and long-term durability compared to those of Pd@Cd ( 1285.9 mA mg Pd − 1 ), Pd@Ag ( 2423.52 mA mg Pd − 1 ) and commercial Pd/C (JM) ( 477.4 mA mg Pd − 1 ) nanocatalysts. The excellent catalytic activity and stability of Pd@Cd1-Ag1 nanocatalyst can be associated to their huge electrochemical active surface area, positive influence of Cd-Ag NPs on Pd NPs and the unique well-organized core-shell nanostructure. These results suggested that the as-synthesized Pd@Cdx-Agy core-shell could serve as advanced catalysts towards alkaline DEFCs.

The exploration of nonhazardous nanoparticles to fabricate a template-driven superhydrophobic surface is of great ecological importance for oil/water separation in practice. In this work, nano-hydroxyapatite (nano-HAp) with good biocompatibility was easily developed from discarded oyster shells and well incorporated with polydimethylsiloxane (PDMS) to create a superhydrophobic surface on a polyurethane (PU) sponge using a facile solution–immersion method. The obtained nano-HAp coated PU (nano-HAp/PU) sponge exhibited both excellent oil/water selectivity with water contact angles of over 150° and higher absorption capacity for various organic solvents and oils than the original PU sponge, which can be assigned to the nano-HAp coating surface with rough microstructures. Moreover, the superhydrophobic nano-HAp/PU sponge was found to be mechanically stable with no obvious decrease of oil recovery capacity from water in 10 cycles. This work presented that the oyster shell could be a promising alternative to superhydrophobic coatings, which was not only beneficial to oil-containing wastewater treatment, but also favorable for sustainable aquaculture.

Facile synthesis of poly (ether sulfone)-based anion exchange membranes (AEMs) bearing flexible pendent quaternary ammonium (QA) groups for fuel cells is reported. (2,3-Epoxypropyl) trimethyl ammonium chloride (EPTMAC) is directly grafted onto the hydroxyl-bearing poly (ether sulfone) (PES) backbone via one-step ring-opening reaction to introduce ion conductive moieties. This scheme is more straightforward than the conventional two-step functionalization approach via chloromethylation or radical-initiated bromination and Menshutkin reactions. This method can be used to control the degree of functionalization of QA-containing PES easily. 2D nuclear overhauser effect spectroscopy (NOESY) shows that QA groups aggregate and self-assemble in the functionalized-PES solutions which are in favor of fabricating a membrane with phase separation morphology, as well as confirmed by small angle X-ray scattering (SAXS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). These resulting AEMs exhibit reasonable hydroxide conductivity, low water uptake, high power density, and desirable durability in a single fuel cell. This suggests that they are good candidates for fuel cells.