The effects of impregnation and reduction conditions on the particle size of Pt and structure of Pt/C catalyst were investigated by TEM, XRD and rotating thin-layer electrode techniques. The results showed that reduct...The effects of impregnation and reduction conditions on the particle size of Pt and structure of Pt/C catalyst were investigated by TEM, XRD and rotating thin-layer electrode techniques. The results showed that reductants affected the particle size and crystal face of platinum in the catalyst and Pt/C catalyst prepared from BP-2000 and by using HCHO as reductant showed a good electrocatalytic activity.展开更多
he nano-graphite sheet/alumina composites were prepared in situ by a facile impregnation-reduction process.The microstructure of the composites was analyzed by X-ray diffraction （XRD）,and the final phase composition...he nano-graphite sheet/alumina composites were prepared in situ by a facile impregnation-reduction process.The microstructure of the composites was analyzed by X-ray diffraction （XRD）,and the final phase composition after reduction is Al2O3,metal Fe and graphite crystal.Scanning electron microscopy （SEM） images show that the particle size of Fe is about 20 nm,and the lamellae thickness of the graphite is about 30 nm.Then,the dielectric properties and conductive mechanism of the composites were investigated experimentally in the frequency range of 0.01-1.00 GHz by impedance analyzer.The results show that the real part of permittivity of composites increases with Fe3＋ concentration,which is due to the increase in interfacial polarization between Fe and A12O3 and the three-dimensional network of lamellar graphite formation.Therefore,tunable microtopography and electrical parameters of nano-graphite sheet/alumina composites can be realized by changing Fe3＋ concentration.展开更多
The goal of this study was to develop and design a composite proton exchange membrane（PEM） and membrane electrode assembly（MEA） that are suitable for the PEM based water electrolysis system. In particular,it focus...The goal of this study was to develop and design a composite proton exchange membrane（PEM） and membrane electrode assembly（MEA） that are suitable for the PEM based water electrolysis system. In particular,it focuses on the development of sulphonated polyether ether ketone（SPEEK） based membranes and caesium salt of silico-tungstic acid（Cs Si WA） matrix compared with one of the transition metal oxides such as titanium dioxide（TiO2）, silicon dioxide（SiO2） and zirconium dioxide（ZrO2）. The resultant membranes have been characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, ion exchange capacity（IEC）, water uptake and atomic force microscopy. Comparative studies on the performance of MEAs were also conducted utilizing impregnation-reduction and conventional brush coating methods. The PEM electrolysis performance of SPEEK-Cs Si WA-ZrO2 composite membrane was more superior than that of other membranes involved in this study. Electrochemical characterization shows that a maximum current density of 1.4 A/cm^2 was achieved at 60 °C, explained by an increased concentration of protonic sites available at the interface.展开更多
文摘The effects of impregnation and reduction conditions on the particle size of Pt and structure of Pt/C catalyst were investigated by TEM, XRD and rotating thin-layer electrode techniques. The results showed that reductants affected the particle size and crystal face of platinum in the catalyst and Pt/C catalyst prepared from BP-2000 and by using HCHO as reductant showed a good electrocatalytic activity.
基金financially supported by the National Natural Science Foundation of China(Nos.50772061 and 51172131)
文摘he nano-graphite sheet/alumina composites were prepared in situ by a facile impregnation-reduction process.The microstructure of the composites was analyzed by X-ray diffraction （XRD）,and the final phase composition after reduction is Al2O3,metal Fe and graphite crystal.Scanning electron microscopy （SEM） images show that the particle size of Fe is about 20 nm,and the lamellae thickness of the graphite is about 30 nm.Then,the dielectric properties and conductive mechanism of the composites were investigated experimentally in the frequency range of 0.01-1.00 GHz by impedance analyzer.The results show that the real part of permittivity of composites increases with Fe3＋ concentration,which is due to the increase in interfacial polarization between Fe and A12O3 and the three-dimensional network of lamellar graphite formation.Therefore,tunable microtopography and electrical parameters of nano-graphite sheet/alumina composites can be realized by changing Fe3＋ concentration.
文摘The goal of this study was to develop and design a composite proton exchange membrane（PEM） and membrane electrode assembly（MEA） that are suitable for the PEM based water electrolysis system. In particular,it focuses on the development of sulphonated polyether ether ketone（SPEEK） based membranes and caesium salt of silico-tungstic acid（Cs Si WA） matrix compared with one of the transition metal oxides such as titanium dioxide（TiO2）, silicon dioxide（SiO2） and zirconium dioxide（ZrO2）. The resultant membranes have been characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, ion exchange capacity（IEC）, water uptake and atomic force microscopy. Comparative studies on the performance of MEAs were also conducted utilizing impregnation-reduction and conventional brush coating methods. The PEM electrolysis performance of SPEEK-Cs Si WA-ZrO2 composite membrane was more superior than that of other membranes involved in this study. Electrochemical characterization shows that a maximum current density of 1.4 A/cm^2 was achieved at 60 °C, explained by an increased concentration of protonic sites available at the interface.
