Synthesis of La_2MoO_6@MWCNTs composite catalysts as Pt-free counter electrodes for dye-sensitized solar cell

Pt-free counter electrode(CE) composed of La2 MoO(LaO-MoO) was successfully synthesized by simple pyrolysis of lanthanum acetate(CHOLa·xHO) and hexaammonium heptamolybdate tetrahydrate((NH4)6 MoO·4 HO). Furthermore,three proportions composites catalysts of La2 MoO@MWCNTs based on La2 MoOand multiwall carbon nanotubes(MWCNTs) were prepared and characterized as Ptfree catalyst for CE in dye-sensitized solar cells(DSSCs). The morphology and structure of La2 MoO@MWCNTs composites were determined by scanning electron microscopy, transmission electron microscope and X-ray diffraction. The electrochemical performance of La2 MoO@MWCNTs composite catalysts for CEs was determined by photocurrent-voltage measurements, cyclic voltammetry,electrochemical impedance spectroscopy, and Tafel polarization. The power conversion efficiencies of4.68%, 4.87% and 5.06% are obtained for La2 MoO:MWCNTs with the mass ratios of 5:1, 3:1 and 1:1 towards the reduction of I~-to I~-under the same conditions,respectively,which are superior to those of MWCNTs(3,94%) and La2 MoO(1.71%) electrodes. The experimental results reveal that the presence of MWCNTs results in an augmented active catalytic surface area and enhanced charge transfer from CE to the electrolyte.

Pt-free counter electrode(CE) composed of La2 MoO_6(La_2 O_3-MoO_3) was successfully synthesized by simple pyrolysis of lanthanum acetate(C_6 H_9 O_6 La·xH_2 O) and hexaammonium heptamolybdate tetrahydrate((NH4)6 Mo_7 O_(24)·4 H_2 O). Furthermore,three proportions composites catalysts of La2 MoO_6@MWCNTs based on La2 MoO_6 and multiwall carbon nanotubes(MWCNTs) were prepared and characterized as Ptfree catalyst for CE in dye-sensitized solar cells(DSSCs). The morphology and structure of La2 MoO_6@MWCNTs composites were determined by scanning electron microscopy, transmission electron microscope and X-ray diffraction. The electrochemical performance of La2 MoO_6@MWCNTs composite catalysts for CEs was determined by photocurrent-voltage measurements, cyclic voltammetry,electrochemical impedance spectroscopy, and Tafel polarization. The power conversion efficiencies of4.68%, 4.87% and 5.06% are obtained for La2 MoO_6:MWCNTs with the mass ratios of 5:1, 3:1 and 1:1 towards the reduction of I_3^-to I^-under the same conditions,respectively,which are superior to those of MWCNTs(3,94%) and La2 MoO_6(1.71%) electrodes. The experimental results reveal that the presence of MWCNTs results in an augmented active catalytic surface area and enhanced charge transfer from CE to the electrolyte.