The AL‐P25 composites (AL = alizarin, P25 = nano titanium dioxide) with oxygen vacancies were synthesized by a simple hydrothermal method and applied for the photoreduction of Cr(VI) under visible light. The AL‐P25 composites were characterized by scanning electron microscopy, X‐ray diffraction, X‐ray photoelectron spectroscopy analysis, Fourier transform infrared spectrometer, thermo‐gravimetric analysis, UV–vis diffuse reflectance spectroscopy, photoluminescence spectroscopy and electron paramagnetic resonance spectroscopy. The results suggested that the AL‐P25 composites were successfully prepared, and alizarin was linked to P25 via Ti—O—C bonds. AL‐P25 composites represented excellent photoreduction efficiency on Cr(VI) under visible light, which was 99.4% after 60 min of illumination. Finally, a photocatalytic mechanism of AL‐P25 composites was proposed that ligand‐metal charge transfer (LMCT) process between alizarin and P25 effectively enhances separation efficiency of photogenerated electrons and holes.

中文翻译：

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带有氧空位的茜素-TiO2 LMCT复合物：Cr（VI）还原的有效可见光催化剂

通过简单的水热法合成具有氧空位的AL-P25复合材料（AL =茜素，P25 =纳米二氧化钛），并将其用于可见光下的Cr（VI）的光还原。AL-P25复合材料的特征在于扫描电子显微镜，X射线衍射，X射线光电子能谱分析，傅立叶变换红外光谱仪，热重分析，紫外可见漫反射光谱，光致发光光谱和电子顺磁共振光谱。结果表明成功制备了AL-P25复合材料，茜素通过Ti-OC键与P25连接。AL-P25复合材料在可见光下对Cr（VI）表现出优异的光还原效率，在照射60分钟后达到99.4％。最后，