Abstract “Black” TiO2 nanotube arrays (TNTAs) of different darkness are formed by thermal reduction of anodic TiO2 nanotube layers in H2 atmosphere at different temperatures (300–500 °C), and their (photo-)electrochemical properties are studied by IPCE spectroscopy, transient photocurrent measurements, IMPS, PEIS, CV, and Mott-Schottky analysis. Hydrogenation of the TNTAs leads to the enhancement of their IPCE (by up to 1.5 times), despite increased recombination losses at anodic potentials. Reduced TNTAs demonstrate a “metallic” behavior by a characteristic frequency response of their impedance and phase angle, reduced charge transfer resistance at anodic bias, increased double layer capacitance, and remarkably increased donor densities (up to 7.25 × 1023 cm−3). The observed alterations in the properties of TNTAs after hydrogenation are ascribed to the formation of defects and TiHx.

中文翻译：

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“渐暗”二氧化钛纳米管阵列的光电化学特性

摘要 在不同温度 (300–500 °C) 的 H2 气氛中通过热还原阳极 TiO2 纳米管层形成不同暗度的“黑色”TiO2 纳米管阵列 (TNTA)，并通过 IPCE 光谱研究它们的（光）电化学性质、瞬态光电流测量、IMPS、PEIS、CV 和 Mott-Schottky 分析。尽管阳极电位下的重组损失增加，但 TNTA 的氢化导致其 IPCE 增强（高达 1.5 倍）。减少的 TNTA 通过其阻抗和相位角的特征频率响应、阳极偏压下电荷转移电阻的降低、双层电容的增加和供体密度的显着增加（高达 7.25 × 1023 cm-3）表现出“金属”行为。