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The sulfonated poly(ether ether ketone) (SPEEK) / polytetrafluoroethylene (PTFE) composite membranes were produced to aid the swelling properties. The PTFE porous films were used as reinforcing material for the SPEEK/PTFE composite membranes. Scanning electron micrographs showed that SPEEK resin was distributed uniformly in the composite membrane and completely plugged the micropores; there is a continuous thin SPEEK film present on the PTFE surface. The dimensional stability and mechanical strength of the composite membranes were apparently improved. The composite membrane had a smaller oxygen permeability than the Nafion® membrane despite it being larger than that of the SPEEK homogenous membrane. The performance and stability of the PEMFC with SPEEK/PTFE composite membranes were also tested. Results showed that the fuel cell had a larger resistance than the SPEEK homogenous membrane or the Nafion® membrane, but these disadvantages are compensated for with the thinner composite membrane, because of its low gas permeability and high mechanical strength. Stability testing showed that the cell performance could be kept steady for more than 150 hours. The structure of the composite membrane didn't undergo any change and a tight bond remained between the composite membrane and the catalyst layers of electrode after more than 300 hours of intermittent operation.

(Ultra) high‐pressure (HP) rocks can be exhumed rapidly by subduction reversal or divergent plate motion. Recent studies show that subduction reversal can in particular occur in a divergent double subduction zone when the slab pull of one slab exceeds that of the other, shorter one, which then experiences a net upward pull. This recent hypothesis, first proposed for Triassic HP‐rocks exposed in the central Qiangtang mélange belt in central Tibet, can explain the exhumation of (ultra) HP rocks through upward slab movement. However, this model lacks the support of kinematic evidence. In this study, based on the recognition of multiple deformational phases, we analyze the kinematics of the HP‐bearing mélange in central Qiangtang. Based on new 40Ar‐39Ar geochronology data and those collected from the literature, we present a temporal framework for the new observations. We recognize a switch in sense of shear between the prograde (D1) and exhumation (D2‐3) paths. The change of shear sense reflects the reversal from downward to upward movement of the oceanic slab below. Early D2 represents the early exhumation stage that caused retrograde metamorphism from eclogite to blueschist facies. No magmatism occurred during this period. Continued exhumation from blueschist facies to greenschist facies resulted in D2‐D3 structures. Voluminous igneous activity occurred during this stage. We suggest that subduction reversal in a divergent double subduction zone can best explain the kinematic evolution and temporal framework above. This exhumation model may provide a new perspective on the exhumation mechanism for other HP rocks around the world. Central Qiangtang HP‐bearing mélange formed by short‐lived southward subduction in a divergent double subduction settingProgressive inversed shearing exhumed HP rocksSubduction reversal in a divergent double subduction zone can exhume HP rocks through direct slab movement

Low-cost blend membranes consisting of sulfonated poly(ether ether ketone) (SPEEK) (an acidic polymer) and polysulfone-4-nitrobenzimidazole (PSf-NBIm) (a basic polymer) have been prepared with various PSf–NBIm contents (0–5.0wt%)and characterized by ion-exchange capacity, proton conductivity, and water uptake measurements. The blend membranes with PSf–NBIm contents of 2.5 and 5.0wt%show higher proton conductivity and lower water uptake in water and methanol/water solutions at a given temperature than plain SPEEK. The blend membranes also exhibit better electrochemical performance and lower methanol crossover in a direct methanol fuel cell than plain SPEEK and Nafion 115 membranes due to an enhancement in proton conductivity through acid-base interactions and an insertion of the benzimidazole side groups into the ionic clusters of SPEEK, as indicated by small-angle X-ray scattering. The maximum power density of the blend membrane with a PSf–NBIm content of 2.5wt%is 1.5 times higher than that of the Nafion 115 in 1Mmethanol solution at 80°C.

Blend membranes consisting of sulfonated poly(ether ether ketone) (SPEEK), which is an acidic polymer, and polysulfone bearing benzimidazole side groups (PSf-BIm), which is a basic polymer, have been prepared with various PSf-BIm contents (0–10wt%). The blend membranes have been characterized by ion exchange capacity, proton conductivity, liquid uptake, methanol permeability, and polarization measurements in direct methanol fuel cell (DMFC). The membranes with an optimum PSf-BIm content of ∼8wt%exhibit electrochemical performance in DMFC better than that of plain SPEEK membrane due to an enhancement in proton conductivity through acid-base interactions and lower methanol crossover.

Water in Nafion 115 membranes was replaced by imidazole and then doped with H3PO4to form imidazole–H3PO4complexes as proton solvent. Both the Nafion–imidazole and Nafion–imidazole–H3PO4composite membranes exhibited higher proton conductivity than the plain Nafion membrane under anhydrous conditions at T100°C. Although the Nafion–imidazole membranes with Pt catalyst exhibit poor performance in proton exchange membrane fuel cells (PEMFCs) at low temperatures (60 and 80°C) due to the poisoning of the Pt catalyst by imidazole, doping with H3PO4improves the fuel cell performance significantly due to the suppression of imidazole poisoning through the formation of imidazolium salt with H3PO4. The imidazole poisoning could also be suppressed further by replacing the Pt catalyst with a newly developed Pd–Co–Mo catalyst. The Nafion–imidazole–H3PO4membranes with the Pd–Co–Mo catalyst show performance superior to that of Nafion membrane with the Pt or Pd–Co–Mo catalyst in PEMFCs at 100°C.