The micropore range of typical MOFs limits the accessibility of substances e.g., dyes have larger sizes. In this work, MIL-121 was transformed into hierarchically porous MOF variants through temperature-regulated linker thermolysis, of which hierarchical porosity (increased average pore size of up to 61.8 Å) and increased specific surface area of up to 346.2 m²/g were achieved. Surface functionality of -COOH and anhydride groups were also improved together with the formation of defective sites and graphite carbon with π-conjugated layers. Improved adsorption of CR and MB were observed with the thermally treated variants, in particular for MIL-121-500 (597.9 and 246.0 mg/g, respectively), when compared with pristine MIL-121 (69.7 and 27.8 mg/g, respectively). Pseudo-second order and Langmuir models were used to explain the adsorption mechanisms. Thermodynamic studies revealed the adsorption of CR and MB on MIL-121-500 were spontaneous, and were endothermic and exothermic, respectively. Characterization of the adsorbents and the DFT calculations demonstrated the synergetic effect of the improved textural and functional properties (especially the oxygen defective sites) of MIL-121-500 was responsible for the enhanced adsorption of dyes. This work sheds light on improving the adsorption performance of MOFs to organic dyes through linker thermolysis and offering a systematic approach to designing custom-built MOFs for targeted applications.

典型 MOF 的微孔范围限制了物质的可及性，例如，染料具有更大的尺寸。在这项工作中，MIL-121 通过温度调节连接器热解转化为分级多孔 MOF 变体，其中分级孔隙率（平均孔径增加高达 61.8 Å）和比表面积增加高达 346.2 m ²/g 实现了。-COOH 和酸酐基团的表面功能性也随着缺陷位点和具有 π 共轭层的石墨碳的形成而得到改善。与原始 MIL-121（分别为 69.7 和 27.8 mg/g）相比，经过热处理的变体观察到 CR 和 MB 的吸附有所改善，特别是对于 MIL-121-500（分别为 597.9 和 246.0 mg/g） . 伪二级和 Langmuir 模型用于解释吸附机制。热力学研究表明 CR 和 MB 在 MIL-121-500 上的吸附是自发的，分别是吸热和放热的。吸附剂的表征和 DFT 计算表明，MIL-121-500 改进的结构和功能特性（尤其是氧缺陷位点）的协同效应是染料吸附增强的原因。这项工作揭示了通过连接体热解提高 MOF 对有机染料的吸附性能，并提供了一种系统的方法来设计用于目标应用的定制 MOF。