染料敏化太阳能电池对电极La_2Mo_2O_7复合MWCNTs非Pt催化剂的制备与性能（英文）

Synthesis and Performance of La_2Mo_2O_7 with MWCNTs Composite Materials as Pt-Free Counter Electrodes for Dye Sensitized Solar Cells

通过高温固相法对醋酸镧(C_6H_9O_6La·x H_2O)与高钼酸铵((NH_4)_6Mo_7O_(24)·4H_2O)在一定条件下热解制备非Pt催化剂La_2Mo_2O_7(La_2O_3-2MoO_2)。进一步采用2种方法将La_2Mo_2O_7与多壁碳纳米管(MWCNTs)进行复合,一种是将La_2Mo_2O_7喷涂到MWCNTs表层之上得到La_2Mo_2O_7/MWCNTs,另一种是将两者均匀混合掺杂得到La_2Mo_2O_7@MWCNTs,再将上述2种复合材料应用于染料敏化太阳能电池对电极进行相应研究。通过扫描电子显微镜(SEM)表征了复合催化材料的微观形貌,X射线衍射(XRD)确定了微观结构。采用电流密度-光电压曲线、循环伏安,交流阻抗以及塔菲尔极化分析了材料的光电性能。实验结果表明在电解液I_3^-/I^-中,基于La_2Mo_2O_7/MWCNTs与La_2Mo_2O_7@MWCNTs的对电极,相同的条件下在光电池中获得的光电转换效率分别为6.09%和4.84%,明显高于MWCNTs的3.94%和La_2Mo_2O_7的0.87%。电极性能的提高可归因于La_2Mo_2O_7复合催化剂相对大的比表面积和高导电性。

A Pt-free counter electrode(CE)composed of La2Mo2O7(La2O3-2MoO2)was successfully synthesized via the simple pyrolysis of lanthanum acetate(C6H9O6La·xH2O)and hexaammonium heptamolybdate tetrahydrate((NH4)6Mo7O24·4H2O)in a high-temperature solid-state reaction.Also,La2Mo2O7 and multiwall carbon nanotubes(MWCNTs)are combined using two methods.La2Mo2O7/MWCNTs was prepared by spray-coating La2Mo2O7 over the surface of MWCNTs,and La2Mo2O7@MWCNTs was synthesized by doping La2Mo2O7 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 La2Mo2O7/MWCNTs and La2Mo2O7@MWCNTs were determined using scanning electron microscopy and X-ray diffraction.The electrochemical performance of the La2Mo2O7/MWCNTs and La2Mo2O7@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 La2Mo2O7/MWCNTs and La2Mo2O7@MWCNTs,respectively,as CEs toward the reduction of I3-/I-ions,and these values are superior to those of MWCNTs(3.94%)and the La2Mo2O7(0.87%)electrode under the same conditions.The enhanced electrode performance was attributed to the relatively larger surface area and higher conductivity of the La2Mo2O7/MWCNTs composite catalysts.