Synthesis of Cr(OH)₃/ZrO₂@Co-based metal-organic framework from waste poly(ethylene terephthalate) for hydrogen production via formic acid dehydrogenation at low temperature

Recycling waste polyethylene terephthalate (PET) bottles into value-added ligand materials for synthesizing metal-organic frameworks (MOFs) derived catalysts is an eco-friendly and economically viable process. The waste PET bottles were readily broken down into 1,4-benzenedicarboxylic acid (BDC) ligands in a highly alkaline environment. Herein, we fabricated a Co@Cr(OH)₃/ZrO₂ catalyst via the carbonization of PET-derived UiO-66 metal-organic frameworks for the catalytic dehydrogenation of formic acid at low temperatures. The as-prepared Co@Cr(OH)₃/ZrO₂ catalyst provides a turnover frequency of 7685 h⁻¹ for hydrogen generation (120 mL in 1.5 min) at ambient temperature. This is due to the uniform dispersion of the fine metal nanoparticle (NPs) (Co NPs, ∼3.75 nm) and the synergistic effect of the Co NPs and Cr( OH)₃/ZrO₂ supports. In addition, the characterization results indicate that porous Zr-MOFs may effectively enclose tiny particles, which is favorable for enhanced dehydrogenation performance. In addition, the Co@Cr(OH)₃/ZrO₂ catalysts demonstrated excellent stability against aggregation and were recyclable over seven cycles without any significant catalytic loss. Thus, this study provides a sustainable methodology for the development of MOF-derived, effective, and stable catalysts for formic acid dehydrogenation towards hydrogen production.