Tailoring properties of PET-derived Sn-MOFs through efficiency structure defects using trifluoroacetic acid (TFA) with water-based facile and green synthesis route

Abstract

Background

The synthesis of Metal-Organic Frameworks (MOFs) is increasingly focused on achieving green and cost-efficient methods while producing high-quality products with abundant active sites. This approach is attracting significant attention from researchers. One promising method, modulated synthesis, stands out for its ability to induce structural defects in MOFs and enhance their active sites. However, the challenges in identifying the optimal conditions for critical factors, particularly the quantitative correlation between the modulator and crucial independent variables influencing MOFs performance, underscore the importance of research work in this field.

Methods

This study synthesized tin-based MOFs (Sn-MOF_s) utilizing a linker derived from recycled polyethylene terephthalate (PET) waste. A hydrothermal approach was employed, utilizing water-like solvents and trifluoroacetic acid (TFA) as a modulator to effectively induce structural defects. Response Surface Methodology (RSM) was applied to evaluate the effects and interactions of temperature, reaction time, and TFA concentration on optimizing yield and crystalline index (CI) while simultaneously reducing the residual percentage of 1,4-benzene dicarboxylate (H₂BDC) in the Sn-MOFs (DI).

Significant findings

The research revealed that temperature, reaction time, and TFA concentration significantly influenced the performance of Sn-MOFs, highlighting the considerable potential of TFA in creating active sites and enhancing the surface area and pore volume of Sn-MOFs through defect engineering. Optimal synthesis conditions for Sn-MOFs included a temperature of 148℃, a reaction time of 24 h, and a molar ratio of H₂BDC/TFA of 1.7, yielding 98.51 ± 1.47 % for yield and 80.21 ± 1.32 % for CI, with no detectable residual H₂BDC. The resulting Sn-MOF-150 exhibited characteristics such as high thermal and chemical stability, abundant function groups, and a unique hierarchical nanostructure composed of spherical nanoparticles. These findings further emphasize the efficacy of the synthesis approach for Sn-MOF through critical parameter optimization and defect engineering techniques.