染料敏化太阳能电池对电极La2Mo2O7复合MWCNTs非Pt催化剂的制备与性能

通过高温固相法对醋酸镧（C₆H₉O₆La·xH₂O）与高钼酸铵（（NH₄）₆Mo₇O₂₄·4H₂O）在一定条件下热解制备非Pt催化剂La₂Mo₂O₇（La₂O₃-2MoO₂）。进一步采用2种方法将La₂Mo₂O₇与多壁碳纳米管（MWCNTs）进行复合，一种是将La₂Mo₂O₇喷涂到MWCNTs表层之上得到La₂Mo₂O₇/MWCNTs，另一种是将两者均匀混合掺杂得到La₂Mo₂O₇@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I₃^-/I^-中，基于La₂Mo₂O₇/MWCNTs与La₂Mo₂O₇@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La₂Mo₂O₇的0.87%。电极性能的提高可归因于La₂Mo₂O₇复合催化剂相对大的比表面积和高导电性。

Synthesis and Performance of La2Mo2O7 with MWCNTs Composite Materials as Pt-Free Counter Electrodes for Dye Sensitized Solar Cells

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 were 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 DSSC 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.