A Pt-free counter electrode(CE)composed of La_(2)Mo_(2)O_(7)(La_(2)O_(3)-2MoO_(2))was successfully synthesized via the simple pyrolysis of lanthanum acetate(C6H9O6La·xH2O)and hexaammonium heptamolybdate tetrahydr...A Pt-free counter electrode(CE)composed of La_(2)Mo_(2)O_(7)(La_(2)O_(3)-2MoO_(2))was successfully synthesized via the simple pyrolysis of lanthanum acetate(C6H9O6La·xH2O)and hexaammonium heptamolybdate tetrahydrate((NH_(4))6Mo_(7)O_(24)·4H2O)in a high-temperature solid-state reaction.Also,La_(2)Mo_(2)O_(7)and multiwall carbon nanotubes(MWCNTs)are combined using two methods.La_(2)Mo_(2)O_(7)/MWCNTs was prepared by spray-coating La_(2)Mo_(2)O_(7)over the surface of MWCNTs,and La_(2)Mo_(2)O_(7)@MWCNTs was synthesized by doping La_(2)Mo_(2)O_(7)into MWCNTs.The two types of composite materials were further used as Pt-free catalytic material in CEs in dye sensitized solar cells(DSSCs).The morphology and microstructure of La_(2)Mo_(2)O_(7)/MWCNTs and La_(2)Mo_(2)O_(7)@MWCNTs were determined using scanning electron microscopy and X-ray diffraction.The electrochemical performance of the La_(2)Mo_(2)O_(7)/MWCNTs and La_(2)Mo_(2)O_(7)@MWCNTs composite catalysts for CEs was determined using photocurrent-voltage measurements,cyclic voltammetry,electrochemical impedance spectroscopy,and Tafel polarization in encapsulation of DSSCs batteries.The experimental results show that power conversion efficiencies of 6.09%and 4.84%were obtained for La_(2)Mo_(2)O_(7)/MWCNTs and La_(2)Mo_(2)O_(7)@MWCNTs,respectively,as CEs toward the reduction of I3-/I-ions,and these values are superior to those of MWCNTs(3.94%)and the La_(2)Mo_(2)O_(7)(0.87%)electrode under the same conditions.The enhanced electrode performance was attributed to the relatively larger surface area and higher conductivity of the La_(2)Mo_(2)O_(7)/MWCNTs composite catalysts.展开更多
The thermotropic phase-transition compounds 1-alkylammonium tetrachlorocobaltate(1-CnH2n+1NH3)2CoCl4(n=10,18)and a series of their binary mixtures were prepared by solution reflux at 353 K in ethanol solutions.Binary-...The thermotropic phase-transition compounds 1-alkylammonium tetrachlorocobaltate(1-CnH2n+1NH3)2CoCl4(n=10,18)and a series of their binary mixtures were prepared by solution reflux at 353 K in ethanol solutions.Binary-mixture(1-C10H21NH3)2CoCl4-(1-C18H37NH3)2CoCl4 systems were characterized over the entire composition range using differential scanning calorimetry and X-ray diffraction.The phase diagram constructed from the experiments indicated one stable intermediate phase,(1-C10H21NH3)-(1-C18H37NH3)CoCl4,at a mass fraction wC10Co=52.51%,two invariant three-phase equilibria,and two eutectoid temperatures,which are assigned to e1 at(347±1)K,for the eutectoid point with wC10Co=38.50%,and e2 at(343±1)K,for the eutectoid point with wC10Co=69.86%.These three clear solid-solution ranges areα-phase on the left,β-phase on the right,andγ-phase in the middle of the phase diagram.The(1-CnH2n+1NH3)2CoCl4 and their binary-mixture systems as phase change materials have phase-transition temperatures in the range 340-370 K,and transition enthalpies in the range 2.13 and 141.12 J·g^-1,between two polymorphic crystal forms.展开更多
文摘A Pt-free counter electrode(CE)composed of La_(2)Mo_(2)O_(7)(La_(2)O_(3)-2MoO_(2))was successfully synthesized via the simple pyrolysis of lanthanum acetate(C6H9O6La·xH2O)and hexaammonium heptamolybdate tetrahydrate((NH_(4))6Mo_(7)O_(24)·4H2O)in a high-temperature solid-state reaction.Also,La_(2)Mo_(2)O_(7)and multiwall carbon nanotubes(MWCNTs)are combined using two methods.La_(2)Mo_(2)O_(7)/MWCNTs was prepared by spray-coating La_(2)Mo_(2)O_(7)over the surface of MWCNTs,and La_(2)Mo_(2)O_(7)@MWCNTs was synthesized by doping La_(2)Mo_(2)O_(7)into MWCNTs.The two types of composite materials were further used as Pt-free catalytic material in CEs in dye sensitized solar cells(DSSCs).The morphology and microstructure of La_(2)Mo_(2)O_(7)/MWCNTs and La_(2)Mo_(2)O_(7)@MWCNTs were determined using scanning electron microscopy and X-ray diffraction.The electrochemical performance of the La_(2)Mo_(2)O_(7)/MWCNTs and La_(2)Mo_(2)O_(7)@MWCNTs composite catalysts for CEs was determined using photocurrent-voltage measurements,cyclic voltammetry,electrochemical impedance spectroscopy,and Tafel polarization in encapsulation of DSSCs batteries.The experimental results show that power conversion efficiencies of 6.09%and 4.84%were obtained for La_(2)Mo_(2)O_(7)/MWCNTs and La_(2)Mo_(2)O_(7)@MWCNTs,respectively,as CEs toward the reduction of I3-/I-ions,and these values are superior to those of MWCNTs(3.94%)and the La_(2)Mo_(2)O_(7)(0.87%)electrode under the same conditions.The enhanced electrode performance was attributed to the relatively larger surface area and higher conductivity of the La_(2)Mo_(2)O_(7)/MWCNTs composite catalysts.
文摘The thermotropic phase-transition compounds 1-alkylammonium tetrachlorocobaltate(1-CnH2n+1NH3)2CoCl4(n=10,18)and a series of their binary mixtures were prepared by solution reflux at 353 K in ethanol solutions.Binary-mixture(1-C10H21NH3)2CoCl4-(1-C18H37NH3)2CoCl4 systems were characterized over the entire composition range using differential scanning calorimetry and X-ray diffraction.The phase diagram constructed from the experiments indicated one stable intermediate phase,(1-C10H21NH3)-(1-C18H37NH3)CoCl4,at a mass fraction wC10Co=52.51%,two invariant three-phase equilibria,and two eutectoid temperatures,which are assigned to e1 at(347±1)K,for the eutectoid point with wC10Co=38.50%,and e2 at(343±1)K,for the eutectoid point with wC10Co=69.86%.These three clear solid-solution ranges areα-phase on the left,β-phase on the right,andγ-phase in the middle of the phase diagram.The(1-CnH2n+1NH3)2CoCl4 and their binary-mixture systems as phase change materials have phase-transition temperatures in the range 340-370 K,and transition enthalpies in the range 2.13 and 141.12 J·g^-1,between two polymorphic crystal forms.
