Wall thickness and charge transport properties of nano-honeycomb TiO2 structures prepared by photoetching
Wall thickness and charge transport properties of nano-honeycomb TiO2 structures prepared by photoetching
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DOI：
10.1016/j.electacta.2006.12.011
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发表时间：
2007-03
影响因子：
6.6
通讯作者：
T. Oekermann;Tsukasa Yoshida;Junko Nakazawa;S. Yasuno;T. Sugiura;H. Minoura
中科院分区：
文献类型：
--
作者：
T. Oekermann;Tsukasa Yoshida;Junko Nakazawa;S. Yasuno;T. Sugiura;H. Minoura
对采用光电化学蚀刻（photoelectrochemical etching）法制备的纳米蜂窝多孔tio2电极进行了时间和频率分辨的光电化学研究。发现通过光刻制备的多孔层中的剩余壁变得大约与材料的空间电荷层厚度的两倍一样薄。因此，从光电流瞬态响应中缓慢分量的出现可以看出，除了在电极的大块部分中通过场驱动迁移进行快速传递外，壁上扩散的缓慢电子传递有助于光电流的产生。在电解质中加入单乙醇胺（MEOA）等电子供体，进一步增强了电子扩散对整体电流响应的贡献。强度调制光电流光谱（IMPS）测量的结果主要由电极的体积部分决定，反映了细胞的RC次数。
Time- and frequency-resolved photoelectrochemical studies have been performed on nano-honeycomb porous TiO2electrodes prepared by photoelectrochemical etching (photoetching). The remaining walls in the porous layers prepared by photoetching are found to become approximately as thin as double the thickness of the space charge layer of the material. Therefore, slow electron transport by diffusion in the walls contributes to the photocurrent generation in addition to the fast transport by field-driven migration in the bulky part of the electrode, as noticed from the appearance of a slow component in the photocurrent transient response. Addition of electron donors such as monoethanolamine (MEOA) to the electrolyte further enhances the contribution of the electron diffusion to the overall current response. The results of intensity modulated photocurrent spectroscopy (IMPS) measurements are dominated by the bulky part of the electrode, reflecting the RC times of the cells.