No abstract

Design and fabrication of alternative proton exchange membrane (PEM) with high proton conductivity is crucial to the commercial application of PEM fuel cell. Inspired by the bioadhesion principle, dopamine‐modified halloysite nanotubes (DHNTs) bearing –NH2 and –NH– groups are facilely synthesized by directly immersing natural halloysite nanotubes (HNTs) into dopamine aqueous solution under mild conditions. DHNTs are then embedded into sulfonated poly(ether ether ketone) (SPEEK) matrix to prepare hybrid membranes. HNTs‐filled hybrid membranes are prepared for comparison. The microstructure and physicochemical properties of the membranes are extensively investigated. Fourier transform infrared analysis implies that ordered acid–base pairs (e.g., –S–O–…+H–HN–, –S–O–…+H–N–) are formed at SPEEK–DHNT interface through strong electrostatic interaction. In such a way, continuous surface‐induced ion‐channels emerge along DHNTs. Although the incorporation of DHNTs reduces the channel size, water uptake, and area swelling of the hybrid membranes, which in turn would reduce the vehicle‐type proton transfer, the acid–base pairs create continuous pathways for fast proton transfer with low energy barrier via Grotthuss mechanism. Consequently, DHNT‐filled hybrid membrane with 15% DHNTs achieves a 30% increase in proton conductivity and a 52% increase in peak power density of single cell when compared with SPEEK control membrane, particularly.

lower temperature. 7 Various chemical methods have been proposed and proven to be eVective in reducing the sintering A series of Z type hexaferrite samples with composition temperature and achieving good properties for hexaferrites Ba 3 Co x Z n 2x Fe 24 O 41 ( x varying f rom 0•0 to 2•0 in such as BaM and Co 2 W. 8 -1 0 steps of 0•4) were prepared by a citrate sol-gel process. To achieve homogeneity of ions at the atomic level in Samples were characterised by T G-DSC, X -ray the precursor and to obtain Z type ferrite at lower temper-diVraction, and scanning electron microscopy. Complex ature, the citrate sol-gel technique is used in the present permittivity and permeability, and dielectric and magpaper to prepare a series of Z type Ba 3 Co x Zn 2x Fe 2 4 O 4 1 netic losses were studied as a function of measurement hexaferrites. The eVects of measurement frequency, sintering f requency, composition, and annealing temperature. temperature, and composition on complex permeability and T he dependence of natural resonant frequency on dielectric constant are also reported. annealing temperature as well as on cobalt content was investigated in the range 100 M H z to 6 GHz. R e ection loss has been calculated as a function of frequency EXPERIMENTAL PROCEDURES according to transmission line theory. BCT /545 Ferrite powder preparation Stoichiometric amounts of ferric citrate, barium carbonate, Dr H. Z hang is at the H igh T emperature Ceramics cobalt nitrate, and zinc nitrate were dissolved in an aqueous