Aiming to reduce the dosage of the noble metal Pt and improve the catalytic activity of the catalyst in fuel cells, hollow porous Ag–Pt alloy nanoparticles with Pt coating are prepared via a facile controlled galvanic replacement reaction. Ag is used as the substrate to build a hollow porous structure and alloyed with Pt to minimize the tensile effect of the Ag on the deposited Pt skin which would significantly lower the catalytic performance of the Ag–Pt bimetallic catalyst. This hollow porous Ag/Pt bimetallic catalyst exhibits a long catalytic durability and a mass activity of 0.438 A mgPt−1 at 0.9 V (vs. RHE) towards the oxygen reduction reaction (ORR), which is ca. 3 times higher than that of the commercial Pt/C catalyst. The significant enhancement over the state-of-the-art Pt catalysts can be attributed to (1) the high surface area of the nanoparticles, (2) the more suitable d-band center of the Pt skin deposited on the Ag–Pt alloy substrate, and (3) the high thermal stability of the Ag–Pt alloy. Therefore, this work provides a new strategy for designing high-performance catalysts with low cost. In addition, the synthetic chemistry involved can possibly be extended for fabricating versatile catalysts with a similar structure.

•Novel mono-sheet bipolar membrane was prepared by pre-irradiation grafting method.•The membranes showed good stability, ionic conductivity and ion exchange capacity.•The thickness of anion/cation exchange layer of the membrane can be easily controlled.•The properties of the membranes can be tuned by varying the degree of grafting.•The membranes were successfully used in the fuel cells without humidification.A new method for the preparation of the mono-sheet bipolar membrane applied to fuel cells was developed based on the pre-irradiation grafting technology. A series of bipolar membranes were successfully prepared by simultaneously grafting of styrene onto one side of the poly(ethylene-co-tetrafluoroethylene) base film and 1-vinylimidazole onto the opposite side, followed by the sulfonation and alkylation, respectively. The chemical structures and microstructures of the prepared membranes were investigated by ATR-FTIR and SEM-EDS. The TGA measurements demonstrated the prepared bipolar membranes have reasonable thermal stability. The ion exchange capacity, water uptake and ionic conductivity of the membranes were also characterized. The H2/O2 single fuel cells using these membranes were evaluated and revealed a maximum power density of 107 mW cm−2 at 35 °C with unhumidified hydrogen and oxygen. The preliminary performances suggested the great prospect of these membranes in application of bipolar membrane fuel cells.

•Novel anion exchange membranes based on pyrrolidonium salts and PVA were prepared.•The properties of the membranes could be tuned by varying the blending ratios.•The membranes showed excellent thermal, chemical and dimensional stability.•The membranes displayed the high OH− conductivity of above 10−2 S cm−1 at 25 °C.•A peek power density of 88.9 mW cm−2 of the H2/air fuel cell was obtained at 65 °C.Novel anion-exchange membranes based on two kinds of pyrrolidonium type ionic liquids, N-methyl-N-vinyl-pyrrolidonium (NVMP) and N-ethyl-N-vinyl-pyrrolidonium (NVEP), have been synthesized via polymerization and crosslinking treatment, followed by membrane casting. The covalent cross-linked structures of these membranes are confirmed by FT-IR. The obtained membranes are also characterized in terms of water uptake, ion exchange capacity (IEC), ionic conductivity as well as thermal, dimensional and chemical stability. The membranes display hydroxide conductivity of above 10−2 S cm−1 at 25 °C. Excellent thermal stability with onset degradation temperature above 235 °C, good alkaline stability in 6 mol L−1 NaOH at 60 °C for 168 h and remarkable dimensional stability of the resulting membranes have been proved. H2/air single fuel cells employed membrane M3 and N3 show the open-circuit voltage (OCV) of 0.953 V and 0.933 V, and the maximum power density of 88.90 mW cm−2 and 81.90 mW cm−2 at the current density of 175 mA cm−2 and 200 mA cm−2 at 65 °C, respectively.

•Novel anion exchange membranes based on two types of imidazolium ionic liquids were synthesized.•The properties of the membranes could be tuned by varying the monomer ratios.•The ionic conductivity of the synthesized membrane is as high as 2.26 × 10−2 S cm−1 at 30 °C.•All the membranes show excellent thermal and chemical stability.•A peek power density of 116 mW cm−2 of the H2/O2 fuel cell is obtained at 60 °C.Novel anion exchange membranes (AEMs) based on two types of imidazolium ionic liquids, 1-vinyl-3-methylimidazolium iodide [VMI]I and 1-vinyl-3-butylimidazolium bromide [VBI]Br, have been synthesized by copolymerization. The obtained membranes are characterized in terms of water uptake, ion exchange capacity (IEC), ionic conductivity as well as thermal and chemical stability. The conductivity reaches 0.0226 Scm−1 at 30 °C. All the membranes show excellent thermostability. The membranes are stable in 10 mol L−1 NaOH solution at 60 °C for 120 h without obvious changes in ion conductivity. Fuel cell performance using the resulting membrane has been investigated. The open circuit voltage (OCV) of the H2/O2 fuel cell is 1.07 V. A peek power density of 116 mW cm−2 is obtained at a current density of 230 mA cm−2 at 60 °C. The results demonstrate the brilliant prospect of the developed membranes for alkaline fuel cell applications.

•Novel fluorinated anion exchange membranes with pyridinium salt were prepared.•The ionic conductivity of the membrane can be as high as 2.7 × 10−2 S cm−1 at 30 °C.•The maximum power density of H2/O2 fuel cell was 124.8 mW cm−2 at 60 °C.•The membranes show good thermal and chemical stabilities.Novel fluorinated anion exchange membranes with pyridinium salt functionalized groups for alkaline anion exchange membrane fuel cells have been prepared and characterized. These membranes have shown a combination of good thermal stabilities, high ionic conductivities, and excellent chemical stabilities. The ionic conductivity of the membranes can be as high as 2.7 × 10−2 S cm−1 in deionized water at 30 °C. An alkaline H2/O2 fuel cell employing the resulting membrane was assembled and revealed a maximum power density of 124.8 mW cm−2 at 60 °C. The preliminary performances have demonstrated their potential as electrolytes for alkaline anion exchange membrane fuel cells.

To develop a series of cross-linked anion exchange membranes for application in fuel cells, poly(ethylene-co-tetrafluoroethylene) (ETFE) films was radiation grafted with vinyl benzyl chloride (VBC), followed by quaternization and crosslinking with 1,4-Diazabicyclo[2,2,2]octane (DABCO), alkylation with p-Xylylenedichloride (DCX), and quaternization again with trimethylamine (TMA). These anion exchange membranes were characterized in terms of water uptake, ion-exchange capacity, ionic conductivity as well as thermal stability. The chemical structures of the membranes were examined by FT-IR. The anion conductivity of the resulting alkaline anion exchange membrane is as high as 0.039 S cm−1 at 30 °C in deionized water and the ionic conductivity increases with the increasing of temperature from 20 to 80 °C. The membrane is stable after being treated by 10 M potassium hydroxide solution at 60 °C for 120 h .The fuel cell performance with the final AAEM obtained in a H2/O2 single fuel cell at 40 °C with this AAEM was 48 mW cm−2 at a current density of 69 mA cm−2.Highlights► ETFE-derived and radiation grafted anion exchange membrane were successfully prepared by two times quaternization method. ► 1,4-Diazabicyclo[2,2,2]octane (DABCO) was used to introduce quaternary ammonium groups and crosslinking structure. ► Elemental analysis and FT-IR results indicated the success of grafting reaction. ► The prepared anion exchange membrane was tested in in-house metal-cation-free H2/O2 fuel cell system. ► The max power density was found to be 48 mW cm−2.

A new polymerizable imidazolium salt monomer, 1-(4-vinylbenzyl)-3-methyl-imidazolium chloride ([VBMI]Cl), has been readily synthesized by reaction of 4-vinylbenzyl chloride with 1-methylimidazole. Novel anion exchange membranes (AEMs) based on the copolymers of [VBMI]Cl and styrene have been prepared and characterized. Excellent thermostability of the membranes is observed through the thermo-gravimetric analysis (TGA) curves. Water uptake and ion exchange capacity (IEC) of the OH− form AEMs range from 26.1% to 61.9% and from 0.95 to 1.45 mmol g−1, respectively. This type of AEM displays significant ionic conductivities over the order of 10−2 S cm−1 in deionized water at room temperature, and the membranes are stable in 10 mol L−1NaOH solution at 60 °C for 120 h. For the H2/air single fuel cell at 30 °C with this novel AEM, the peak power density of 33 mW cm−2 is obtained at a current density of 59 mA cm−2.

Novel anion exchange membranes based on the copolymers of 1-allyl-3-methylimidazolium chloride (AmimCl) ionic liquid either with methyl methacrylate (MMA) or butyl methacrylate (BMA) have been prepared via free radical polymerization. The structures and characteristic properties of the membranes are studied. It is found that the hydroxyl ionic conductivity of the synthesized membrane can reach 3.33 × 10−2 S cm−1 in deionized water at 30 °C. The methanol permeability is less than 10−9 mol cm2 s−1 even at 60 °C. These membranes with imidazolium salt functional groups exhibit superior stability both chemically and thermally as well compared to the alkyl quaternary ammonium functionalized polymers. Therefore, the membranes have good perspectives and great potential for alkaline fuel cell applications.Research highlights▶ This article briefly highlights the stability both in thermal and chemical of imidazole-type anion exchange membrane. ▶ Building on previous research work in this area, it provides a new way to prepared a novel material, which has many merits, such as high ionic conductivity, excellent chamical stability as well as thermal stability, low methanol permeability. ▶ It provides a new material which has good perspectives and great potential for alkaline fuel cell appliacation.

Aiming to reduce the dosage of the noble metal Pt and improve the catalytic activity of the catalyst in fuel cells, hollow porous Ag–Pt alloy nanoparticles with Pt coating are prepared via a facile controlled galvanic replacement reaction. Ag is used as the substrate to build a hollow porous structure and alloyed with Pt to minimize the tensile effect of the Ag on the deposited Pt skin which would significantly lower the catalytic performance of the Ag–Pt bimetallic catalyst. This hollow porous Ag/Pt bimetallic catalyst exhibits a long catalytic durability and a mass activity of 0.438 A mgPt−1 at 0.9 V (vs. RHE) towards the oxygen reduction reaction (ORR), which is ca. 3 times higher than that of the commercial Pt/C catalyst. The significant enhancement over the state-of-the-art Pt catalysts can be attributed to (1) the high surface area of the nanoparticles, (2) the more suitable d-band center of the Pt skin deposited on the Ag–Pt alloy substrate, and (3) the high thermal stability of the Ag–Pt alloy. Therefore, this work provides a new strategy for designing high-performance catalysts with low cost. In addition, the synthetic chemistry involved can possibly be extended for fabricating versatile catalysts with a similar structure.

A new polymerizable imidazolium salt monomer, 1-(4-vinylbenzyl)-3-methyl-imidazolium chloride ([VBMI]Cl), has been readily synthesized by reaction of 4-vinylbenzyl chloride with 1-methylimidazole. Novel anion exchange membranes (AEMs) based on the copolymers of [VBMI]Cl and styrene have been prepared and characterized. Excellent thermostability of the membranes is observed through the thermo-gravimetric analysis (TGA) curves. Water uptake and ion exchange capacity (IEC) of the OH− form AEMs range from 26.1% to 61.9% and from 0.95 to 1.45 mmol g−1, respectively. This type of AEM displays significant ionic conductivities over the order of 10−2 S cm−1 in deionized water at room temperature, and the membranes are stable in 10 mol L−1NaOH solution at 60 °C for 120 h. For the H2/air single fuel cell at 30 °C with this novel AEM, the peak power density of 33 mW cm−2 is obtained at a current density of 59 mA cm−2.