Upcycling Waste PET into High-Performance CO2 Adsorbents via Scalable Molten Salt-Assisted Carbonization

Abstract Converting waste PET into porous carbon materials for CO2 capture is a promising strategy to achieve waste valorization and carbon neutrality, yet existing methods still suffer from limited structural control, incomplete carbonization, and unclear structural evolution mechanisms. Herein, a facile molten salt-assisted carbonization strategy was developed to fabricate carbon nanosheets (CNS) from waste PET. The effects of molten salt type, ratio, and carbonization temperature on the morphology, pore structure, and surface chemistry of the as-prepared CNS were systematically investigated. The results show that the optimal sample exhibits an ultrathin 2D nanosheet structure with a high surface area of 1825 m2·g–1. This sample exhibited a high CO2 adsorption capacity of 3.87 mmol·g–1, outperforming most reported PET-derived porous carbon materials. Based on systematic characterizations, the intrinsic regulation mechanism of molten salt on the structural evolution of PET-derived carbon was revealed. This work provides a facile and sustainable route for the high-value utilization of waste PET plastic and also offers theoretical support for the design of high-performance CO2 adsorbents.