Upcycling of Waste Polyethylene Terephthalate Plastics to Fabricate Cobalt–Nickel Metal–Organic Frameworks and Their Phosphides for Efficient Oxygen Evolution Reaction

ABSTRACT

The urgent environmental crisis caused by polyethylene terephthalate (PET) waste necessitates efficient upcycling strategies. Herein, we establish a novel pathway to transform waste PET plastic into a high‐performance catalytic material for mediating the oxygen evolution reaction (OER). Through a one‐step hydrothermal process, waste PET serves as a precursor for the direct construction of a bimetallic cobalt–nickel metal–organic framework (Co ₄ Ni‐MOF), which subsequently undergoes phosphidation to yield Co ₄ NiP‐400. The resultant phosphide catalyst has outstanding OER efficacy in alkaline environments, requiring a minimal overpotential of merely 287 mV to get a current density of 10 mA cm ⁻² , and revealing a modest Tafel slope of 51 mV dec ⁻¹ . Moreover, the catalyst has exceptional long‐term stability, preserving its activity after 24 h of continuous operation and 1000 cycles of cyclic voltammetry. Theoretical simulations indicate that the phosphidation process efficiently modifies the electronic structure, enhances the adsorption energy of reaction intermediates, and changes the rate‐determining step, thus reducing the reaction energy barrier. A life‐cycle assessment (LCA) indicates that this PET upcycling synthesis route significantly reduces the environmental impact, decreasing greenhouse gas emissions by 8.93% and marine eutrophication potential by 25.82% compared to conventional synthesis pathways. This work not only provides a sustainable method for waste plastic valorization but also offers a strategic design for cost‐effective and environmentally benign advanced electrocatalysts.