Visually black, electrically leaky, amorphous titania (am-TiO₂) thin films were grown by atomic layer deposition (ALD) for photocatalytic applications. Broad spectral absorbance in the visible range and exceptional conductivity are attributed to trapped Ti³⁺ in the film. Oxidation of Ti³⁺ upon heat treatment leads to a drop in conductivity, a color change from black to white, and crystallization of am-TiO₂. ALD-grown black TiO₂, without any heat treatment, is subject to dissolution in alkaline photoelectrochemical conditions. The best photocatalytic activity for solar water splitting is obtained for completely crystalline white TiO₂.

中文翻译：

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TiO _2的多样性：控制原子层沉积黑色TiO ₂的分子和电子结构

通过原子层沉积（ALD）生长视觉上呈黑色，漏电的非晶态二氧化钛（am-TiO ₂）薄膜，以进行光催化应用。可见光范围内的宽光谱吸收和出色的电导率归因于薄膜中捕获的Ti ³⁺。热处理时Ti ^3+的氧化导致电导率下降，颜色从黑色变为白色以及am-TiO ₂结晶。ALD生长的黑色TiO ₂未经任何热处理，在碱性光电化学条件下会溶解。对于完全结晶的白色TiO _2，获得了最佳的太阳能水分解光催化活性。