Nowadays, increasing awareness of environment and fossil fuels protection stimulates intensive research on clean and renewable sources of energy. Production of hydrogen from water through solar-driven splitting reactions is one of the most promising approaches in the field of photoelectrochemistry (PEC). In this work we have fabricated well-aligned, highly-ordered, smooth-mouth TiO₂ nanotube arrays (TNAs) in a two-step anodization process of titanium foil, which were then used as photoelectrodes for PEC water splitting. It demonstrates for the first time correspondence between non-linear component characteristics of multiscale rough surface and crystalline structure of annealed TNAs measured at various fabrication stages and their photoelectrochemical response. The as-anodized TNAs with isotropic surface (deduced from AFM and SEM images) and largest figure of merit (according to their PEC performance) were annealed at 450 °C in air. Scale-invariant descriptors of the surface structure of the deposits involved: fractal dimension, corner frequency, roughness, size of nanostructures and their dominant habits. Moreover, X-ray diffraction data processed using the Rietveld method confirmed co-existence of various oxides, for example: TiO₂ in the form of anatase, TiO and Ti₃O₅ phases in the TNAs under study pointing that previous well-established mechanisms of the TNA growth were to certain degree incomplete.

中文翻译：

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用于光电化学水分解的取向TiO2纳米管的粗糙表面几何形状和晶体结构的演变。

如今，对环境和化石燃料保护的认识不断提高，刺激了人们对清洁和可再生能源的深入研究。通过太阳能驱动的分裂反应从水中生产氢是光电化学（PEC）领域中最有希望的方法之一。在这项工作中，我们制造了排列整齐，高度有序的光滑嘴TiO ₂钛箔的两步阳极氧化工艺中的纳米管阵列（TNA），然后将其用作PEC水分解的光电极。它首次展示了多尺度粗糙表面的非线性成分特征与退火TNA在不同制造阶段测得的晶体结构之间的对应关系及其光电化学反应。将具有各向同性表面（根据AFM和SEM图像得出）和最大品质因数（根据其PEC性能）的阳极氧化的TNA在450°C的空气中进行退火。所涉及沉积物表面结构的尺度不变描述符：分形维数，拐角频率，粗糙度，纳米结构的大小及其主要习性。此外，使用Rietveld方法处理的X射线衍射数据证实了各种氧化物的共存，₂在研究中的TNA中以锐钛矿，TiO和Ti ₃ O ₅的形式出现，指出先前公认的TNA生长机理在一定程度上是不完整的。