Iron-based MOFs have been considered as the candidate for Fenton-like reagents owing to their open pore size and uniformly dispersed Fe active centers. However, the strong coordination of metal ions with organic ligands greatly reduces the exposed active sites of most iron-based MOFs, thus reducing Lewis acid sites and limiting the activation efficiency of H₂O₂. At the same time, low Fe³⁺/Fe²⁺ cycle efficiency also restricts H₂O₂ activation efficiency. Hence, in this work, a series of MIL-100 (Fe) containing mixed valence coordinatively unsaturated metal site (CUS) with different Fe²⁺/Fe³⁺ ratios was synthesized by heat treatment and used for tetracycline hydrochloride (TC-HCL) degradation with the assistance of visible light. Interestingly, accelerated Fe³⁺/Fe²⁺ cycle was observed with the aid of visible light. Among the prepared samples, CUS-MIL-250 prepared under vacuum at 250℃ has superior degradation performance, primarily owing to its large specific surface area and pore volume, improved visible light absorption, and the introduction of more Fe²⁺ CUS. Meanwhile, compared with Fenton-like system and photocatalytic system, the CUS-MIL-250/H₂O₂/Vis system, with effective separation of photogenerated electrons and holes, demonstrates a synergistic effect to generate more reactive oxidation species, thereby improving the degradation efficiency. In addition, the catalyst shows good stability and recyclability.

铁基MOF由于其开孔尺寸和均匀分布的Fe活性中心而被认为是Fenton类试剂的候选者。但是，金属离子与有机配体的强配位大大降低了大多数铁基MOF的暴露活性位，从而降低了路易斯酸位并限制了H ₂ O ₂的活化效率。同时，低的Fe ³⁺ / Fe ²⁺循环效率也限制了H ₂ O _2的活化效率。因此，在这项工作中，一系列含有不同价态的Fe ²⁺ / Fe ^3+的混合价配位不饱和金属位点（CUS）的MIL-100（Fe）通过热处理合成这些比率，并在可见光的辅助下将其用于盐酸四环素（TC-HCL）降解。有趣的是，借助于可见光观察到加速的Fe ³⁺ / Fe ²⁺循环。在制备的样品中，在250℃真空下制备的CUS-MIL-250具有优异的降解性能，这主要是由于其比表面积和孔体积大，可见光吸收率提高以及引入了更多的Fe ²⁺ CUS。同时，与类芬顿体系和光催化体系相比，CUS-MIL-250 / H ₂ O ₂/ Vis系统有效分离了光生电子和空穴，显示出产生更多反应性氧化物质的协同效应，从而提高了降解效率。另外，该催化剂显示出良好的稳定性和可回收性。