Solar reforming of plastics using acid-catalyzed depolymerization

Abstract

The accumulation of plastics such as polyethylene terephthalate (PET), Nylon 66, and polyurethane (PU) presents an environmental challenge that requires scalable circular solutions. Here, we report photoreforming (PR) of acid-hydrolyzed waste plastics into H2 and value-added products using an acid-stable photocatalyst composed of cyanamide-functionalized carbon nitride integrated with cobalt-promoted molybdenum disulfide (CoMoS2–CNx). Under AM 1.5G irradiation, CoMoS2–CNx yields 0.35 ± 0.02 mmol H2 gcat −1 from PET, increasing to 1.9 ± 0.1 mmol H2 gcat −1 under 405 nm LED (33 mW cm−2) irradiation. In 24 h, Nylon 66 and PU yield 1.0 ± 0.4 and 4.2 ± 0.1 mmol H2 gcat −1, respectively. From stability tests, the catalyst remains active over 11 days, affording up to 40% ethylene glycol conversion, 89% acetic acid selectivity, and a 9.0% quantum yield. Acid hydrolysis, enabled by recycled sulfuric acid from spent lead-acid batteries, underpins technoeconomic viability, indicating profitable solar-driven processing of ton-scale plastic waste.