Novel edge-epitaxial MOF on MOF for efficient nizatidine removal

Background

Metal organic frameworks (MOFs) have shown potential for photocatalytic of pollutants, via generation of reactive oxygen species like singlet oxygen (¹O₂). However, enhancing the photocatalytic performance of MOFs remains a challenge. Addressing this challenge is particularly important because removing pharmaceuticals like nizatidine (NZT) is crucial to prevent the formation of carcinogenic N-nitrosodimethylamine during water treatment processes.

Methods

A novel MOF on MOF photocatalyst (PCN-134/PCN-134) was synthesized through an epitaxial edge growth strategy. Firstly, PCN-134 was utilized as the seed MOF, upon which the secondary MOF Zr-BTB was grown epitaxially on its edges. Subsequently, the photosensitizer Tetrakis(4-carboxyphenyl) porphyrin was integrated onto the surface of Zr-BTB via a microwave-assisted solvothermal process.

Significant findings

Compared to the pristine PCN-134, the PCN-134/PCN-134 exhibited significantly enhanced photodegradation efficiency towards NZT under optimal conditions (85.07% vs. 47.5 %). It had been demonstrated that ¹O₂ was the key reactive oxygen species responsible for the degradation of NZT. Notably, the photodegradation system had excellent immunity to interference, with a drop in removal of no more than 5 % and 15 % in the presence of common ions and soluble organics, respectively. Additionally, it showed excellent removal for NZT in various water matrices. This study highlights the potential of the MOF on MOF epitaxial growth strategy in enhancing the photocatalytic performance of MOFs for environmental remediation applications.