Series TiO₂/MIL-125 core-shell composites were fabricated from MIL-125 via in-situ post-solvothermal method. The composites composed of TiO₂ as shell and MIL-125 as core demonstrated some advantages like abundant linker defects, mesoporous structure and unsaturated titanium-oxo clusters, which enabled it to be a desired photocatalyst. The photocatalytic Cr(VI) reduction performances of as-prepared TiO₂/MIL-125 composites with different treatment times were evaluated under Xe lamp irradiation. The results indicated that optimal marigold-flower-like MT-2 (TiO₂/MIL-125 composite produced by treating MIL-125 for 2 h) exhibited superior photocatalytic Cr(VI) reduction activity than those of pristine MIL-125 precursor, TiO₂/MIL-125 composites produced by treating MIL-125 for 1 h, and the completely derived TiO₂. The TiO₂ nanosheet formed from the outer-to-inner loss of organic ligands in the MIL-125 precursor can boost the separation efficiency of photo-induced carriers. Within this work, the influence of operation factors including pH values, foreign ions and organic acids with small molecular weight on photocatalytic Cr(VI) reduction were explored. The apparent quantum efficiency of optimal MT-2 was calculated under different monochromatic light. As well, the possible mechanism of photocatalytic Cr(VI) reduction over MT-2 was proposed and confirmed by electrochemical determination, active species trapping experiments and electron spin resonance analyses.

TiO ₂ / MIL-125系列核壳复合材料是通过MIL-125原位后溶剂热法制备的。以TiO ₂为壳，MIL-125为核的复合材料表现出一些优势，如大量的连接缺陷，中孔结构和不饱和的钛-氧代簇，使其成为理想的光催化剂。在氙灯照射下评价了不同处理时间的TiO ₂ / MIL-125复合材料的光催化Cr（VI）还原性能。结果表明，与原始MIL-125前体TiO相比，最佳的万寿菊花状MT-2（通过MIL-125处理2 h生产的TiO ₂ / MIL-125复合材料 ）表现出优异的光催化Cr（VI）还原活性。₂ / MIL-125复合材料通过将MIL-125处理1  h和完全衍生的TiO ₂制成。由MIL-125前体中有机配体的从内到外的损失形成的TiO ₂纳米片可以提高光诱导载流子的分离效率。在这项工作中，探索了包括pH值，外来离子和小分子量有机酸在内的操作因素对光催化Cr（VI）还原的影响。在不同的单色光下，计算出最佳MT-2的表观量子效率。提出了MT-2光催化还原Cr（VI）的可能机理，并通过电化学测定，活性物种捕获实验和电子自旋共振分析得到了证实。