Titanium dioxide nanotube array (TiO₂ NTA) grown on titanium substrate has been fabricated as active photoelectrode for organic compound degradation. TiO₂ NTA shows the tubewall-separated nanotube arrangement and anatase crystal structure. Transient photocurrent of 1.86 mA and open-circuit photovoltage of 0.26 V are determined to keep stable level under ultraviolet (UV) light irradiation, indicating its high photoelectrochemical activity. The cathodic polarization process causes more feasible electron transfer than the equilibrium process and anodic polarization process, which is consistent with the declining current response at an increasing positive potential. The photocatalytic activity of TiO₂ NTA is fully evaluated through UV light-induced photocatalysis and photoelectrocatalysis degradation of organic dye X-3B as a reactant pollutant. The pseudo-first-order reaction rate constant is enhanced from 0.00346 min⁻¹ for photocatalysis to 0.00521 min⁻¹ for photoelectrocatalysis using Langmuir–Hinshelwood kinetic model of heterogeneous catalysis. The tubewall-separated nanotube structure could induce photoelectron directional transport and provide extra interspace for reactant organic molecule diffusion at accessible surface area. The positive potential applied on TiO₂ NTA could further promote photoelectron–hole pair separation. Two strategies of photoelectron generation and photoelectron–hole separation are accordingly adopted to improve its electro-assisted photocatalytic activity. Therefore, the tubewall-separated TiO₂ NTA could present the promising photoelectrocatalysis application.

中文翻译：

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管壁分离二氧化钛纳米管阵列光电极的光电化学性能

在钛基板上生长的二氧化钛纳米管阵列 (TiO ₂ NTA) 已被制造为用于有机化合物降解的活性光电极。TiO ₂ NTA 显示管壁分离的纳米管排列和锐钛矿晶体结构。确定 1.86 mA 的瞬态光电流和 0.26 V 的开路光电压在紫外 (UV) 光照射下保持稳定水平，表明其具有较高的光电化学活性。阴极极化过程比平衡过程和阳极极化过程引起更可行的电子转移，这与正电位增加时电流响应下降是一致的。TiO ₂的光催化活性通过紫外光诱导的光催化和光电催化降解有机染料 X-3B 作为反应物污染物，对 NTA 进行了全面评估。伪一级反应速率常数从0.00346分钟增强^-1为光催化0.00521分钟^-1，使用多相催化的朗缪尔-欣谢尔伍德动力学模型光电催化。管壁分离的纳米管结构可以诱导光电子定向传输，并为反应物有机分子在可及表面积的扩散提供额外的间隙。施加在 TiO ₂上的正电位NTA 可以进一步促进光电子-空穴对分离。相应地采用光电子产生和光电子-空穴分离两种策略来提高其电辅助光催化活性。因此，管壁分离的 TiO ₂ NTA 具有广阔的光电催化应用前景。