Abstract Highly ordered TiO2 nanotube (TiNT) arrays were prepared on Ti foil. The interfacial caps between nanotube bottom and Ti foil were gradually removed by oxalic acid. The removal of caps in TiNT is known to enhance its light-harvesting capability, increase the carrier transfer, and cause effective dissociation of electron-hole pairs. The electronic and local atomic structures of TiNT at different oxalicacid immersion time were investigated by XAS. Notably, the reported enhanced light harvesting and electron collecting efficiencies in both-end open TiNT, could be strongly correlated with charge redistribution in Ti 3d orbital and structural defect. An increase in Ti 3d unoccupied states due to increase in Ti4+/Ti3+ ratio followed by a decrease in oxygen vacancy at the closed-end bottom caps after 16 h oxalicacid immersion might be one of the reasons for enhanced efficiency of both end open TiNT against one end open tube. EXAFS analysis revealed an increase in CN number and Ti–O bond length, which results in the formation of disordered TiO6 Oh symmetry that would possibly enhance the lattice phonons and eventually the efficiency of TiNT. This is one of the fundamental reasons for the improved photocatalytic properties for both-end open TiNT against closed bottom-end nanotubes.

中文翻译：

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提高 TiO2 开放纳米管阵列的光催化效率：XAS 的观点

摘要 在钛箔上制备了高度有序的 TiO2 纳米管 (TiNT) 阵列。纳米管底部和钛箔之间的界面帽被草酸逐渐去除。众所周知，去除 TiNT 中的帽可以增强其捕光能力，增加载流子转移，并导致电子 - 空穴对的有效离解。通过XAS研究了不同草酸浸渍时间下TiNT的电子和局部原子结构。值得注意的是，据报道，两端开放式 TiNT 中增强的光收集和电子收集效率可能与 Ti 3d 轨道和结构缺陷中的电荷重新分布密切相关。由于 Ti4+/Ti3+ 比值增加导致 Ti 3d 未占据态增加，然后在草酸浸渍 16 小时后封闭端底盖处的氧空位减少可能是两端开口 TiNT 相对于一个端部的效率提高的原因之一。 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?端开管。EXAFS 分析显示 CN 数和 Ti-O 键长增加，导致形成无序的 TiO6 Oh 对称性，这可能会增强晶格声子并最终提高 TiNT 的效率。这是两端开放式 TiNT 对封闭底端纳米管的光催化性能提高的根本原因之一。这导致形成无序的 TiO6 Oh 对称性，这可能会增强晶格声子并最终提高 TiNT 的效率。这是两端开放式 TiNT 对封闭底端纳米管的光催化性能提高的根本原因之一。这导致形成无序的 TiO6 Oh 对称性，这可能会增强晶格声子并最终提高 TiNT 的效率。这是两端开放式 TiNT 对封闭底端纳米管的光催化性能提高的根本原因之一。