长度可调的TiO_2纳米管制备及其DSSC性能的研究

Preparation of length-modulated TiO_2 nanotube arrays and their application in DSSC

采用阳极氧化法在Ti片上制备高度取向的TiO2纳米管阵列。室温下,电压60V,在含有0.5%(质量分数)NH4F,1%(体积分数)HF,2%(体积分数)H2O的乙二醇电解液中,通过改变阳极氧化时间(8～20h),反应制得管长约为6.7～19.5μm,管径约为90～110nm,管壁约为20nm的TiO2纳米管阵列。利用SEM、TEM、EDS对TiO2纳米管的形貌和化学组分进行表征。采用XRD、SAED证实TiO2纳米管阵列的结构。分析不同长度纳米管阵列紫外-可见光反射率曲线,发现较长的纳米管对可见光有更强的吸收能力。将不同长度的纳米管阵列封装成染料敏化电池(DSSC),研究纳米管长度对电池性能参数的影响。

A two-electrode cell has been utilized to anodize Ti foils for obtaining highly oriented TiO2 nanotube（NT） arrays.The morphology and composition of the TiO2 NT arrays were characterized by scanning electron microscope（SEM） and energy dispersive spectra（EDS）.Depending upon the anodization time（8-20h）,the lengths and diameters of TiO2 NT arrays was arranged from 6.7 to 19.5μm,and 90 to 110nm,respectively.As confirmed by X-ray diffraction（XRD） and selected area electron diffraction（SAED）,the as-anodized TiO2 NTs were amorphous but transformed into anatase phase after thermal annealing at 450℃ for 3h.Reflectance spectrum of TiO2 NT arrays showed that the layer with longer NTs can lower the reflectance in the visible spectrum,thus enhancing light harvesting for dye-sensitized solar cells（DSSC）.The photocurrent density-voltage（J-V） characteristics of TiO2 NT-based DSSCs showed that higher energy conversion efficiencies can be achieved with longer TiO2 NT lengths.