Though there are numerous intrinsic merits of metal-organic frameworks (MOFs), low charge separation efficiency has imposed heavy restrictions on their photocatalytic application. Herein, in situ porphyrin ligand substitution, as a strategy for improving the charge separation efficiency and increasing the amounts of active sites, has been designed and realized in a Hf-biphenyl dicarboxylic acid (BPDC) MOF. Specifically, a size and geometry matched meso-tetra (4-carboxyphenyl) porphyrin (TCPP) ligand was selected and doped into Hf-BPDC MOF by forming coordinating bonds with Hf centers, forming dual-ligand Hf-BPDC-TCPP MOF. The resultant Hf-BPDC-TCPP MOF showed significantly improved activity and chemical stability in the photocatalytic H₂ generation (261 μmol·g⁻¹·h⁻¹) and tetracycline (TC) degradation reactions (95.8%), which was 48 and 1.47 folds higher than that of the Hf-BPDC MOF. Photophysical and electrochemical studies revealed that the introduction of porphyrin ligand could generate a stronger internal electric field for boosting the charge separation and transfer, increase the specific surface area for providing more active sites, and narrow the band gap to enhance the visible light absorption. This in situ ligand substitution method provides a promising approach to build a tunable platform for constructing high-performance MOF photocatalysts.

Graphical Abstract

中文翻译：

---

Hf-MOF 中的原位内消旋四（4-羧基苯基）卟啉配体取代可增强光氧化还原反应中的催化活性和稳定性

尽管金属有机框架（MOF）有许多内在优点，但低电荷分离效率对其光催化应用造成了严重限制。本文中，原位卟啉配体取代作为提高电荷分离效率和增加活性位点数量的策略，已在Hf-联苯二甲酸（BPDC）MOF中设计并实现。具体来说，选择尺寸和几何形状匹配的内消旋四（4-羧基苯基）卟啉（TCPP）配体，并通过与Hf中心形成配位键将其掺杂到Hf-BPDC MOF中，形成双配体Hf-BPDC-TCPP MOF。所得Hf-BPDC-TCPP MOF在光催化H ₂生成（261 μmol·g ^-1 ·h ^-1）和四环素（TC）降解反应（95.8%）中表现出显着改善的活性和化学稳定性，分别为48和1.47倍数高于 Hf-BPDC MOF。光物理和电化学研究表明，卟啉配体的引入可以产生更强的内电场以促进电荷分离和转移，增加比表面积以提供更多活性位点，并缩小带隙以增强可见光吸收。这种原位配体取代方法为构建高性能 MOF 光催化剂的可调平台提供了一种有前途的方法。

图形概要