透明TiO2纳米管/FTO电极制备及表征

采用射频磁控溅射方法在透明导电玻璃(FTO)上沉积纯钛薄膜, 室温条件下在H3PO4+HF电解液中通过恒压阳极氧化方法得到TiO2纳米管阵列, 并通过场发射扫描电子显微镜(FESEM)、X射线衍射(XRD)、UV-Vis透射光谱以及光电化学的方法对纳米管阵列进行了表征. 研究表明, 在电压为20 V、氧化时间为50 min时, 钛薄膜转化为TiO2纳米管阵列, 管长约为380 nm, 内径约为90 nm, 管壁约为15 nm; 再经过500 ℃空气热处理6 h之后得到锐钛矿型的TiO2纳米管/FTO透明电极, 在可见光区的平均透过率约为80%, TiO2禁带宽度为3.28 eV, 发生了蓝移, 带尾扩展到2.6 eV; 此外, 对结晶前后的复合电极分别在暗态和紫外光下进行线性扫描和瞬态光电流测试, 结果表明, 结晶的电极表现出更好的光电转换性能; 施加阳极电压和紫外光照射都能够促进TiO2光生载流子有效分离,使电子迅速传至导电玻璃表面通过外电路形成光电流.

Fabrication and Characterization for Transparent Electrodes of TiO2 Nanotube Arrays on Fluorine-Doped Tin Oxide-Coated Glass

A highly ordered TiO2 nanotube layer was fabricated on fluorine-doped tin oxide-coated glass substrate (FTO) by potentiostatic anodization of pure titanium film at room temperature, which was deposited by radio frequency (RF) magnetron sputtering. The structure and the composition of the as prepared TiO2 nanotubes were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), UV-Vis transmission spectra, and photoelectrochemistry methods. The results showed that the Ti films converted to TiO2 nanotubes of 380 nm length, 90 nm pore diameter, and 15 nm wall thickness at the voltage of 20 V for 50 min. After annealing at 500 ℃ for 6 h in air, the anatase phase of TiO2 nanotube/FTO transparent electrodes were obtained, which had an average transmittance of 80% in visible wavelength range. The bandgap of TiO2 was determined as 3.28 eV, with a bandgap tail extending to 2.6 eV. Moreover, the photoelectrochemistry measurements indicated that the crystallized electrode exhibited a significant improvement of photoelectrochemical current response in comparison with the as-anodized electrode, and both the electrode potential and UV-illumination surely enhanced the effective separation of the electron-hole pairs, leading to the fact that the photo-induced electrons transferred quickly to the conducting glass via external circuit and formed photocurrent.