A recent study by Prof. Minghua Huang’s team from the School of Materials Science and Engineering has made significant progress in electrochemical catalytic upcycling of plastics. The research, titled *Promoted OH Adsorption Facilitates C─C Bond Cleavage for Efficient Electrochemical Upcycling of Polyethylene Terephthalate, was published in the internationally renowned journal ACS Catalysis (IF: 13.084).
Polyethylene terephthalate (PET), a petroleum-based high-molecular-weight thermoplastic material, is a critical foundational material in modern industry and daily life. However, discarded PET is inherently resistant to natural degradation, making it a major contributor to white pollution and posing significant threats to ecological safety and human health. Renewable energy-driven electrochemical methods offer a promising solution by oxidizing ethylene glycol—the hydrolyzate of PET—into high-value chemicals while simultaneously enabling hydrogen evolution reaction at the cathode. This process reintroduces underutilized carbon resources into economic cycles, aligning with global efforts toward carbon neutrality and sustainable development. Nevertheless, the adsorption mechanism of key reaction intermediates during ethylene glycol oxidation remains unclear, presenting a critical scientific challenge for improving reaction efficiency and selectivity.
To address these challenges, Prof. Minghua Huang’s research group successfully synthesized amorphous CoNiOOH/NF and amorphous/crystalline interfacial CoNiOOH-Ni₃S₂/NF via simple electrochemical activation time tuning. These materials were used as model catalysts to investigate the underlying mechanisms of ethylene glycol conversion to formate. Detailed characterization and theoretical calculations revealed that compared to amorphous CoNiOOH/NF, the amorphous/crystalline interface of CoNiOOH-Ni₃S₂/NF modulates the electronic structure, shifting the d-band center closer to the Fermi level. This significantly enhances the adsorption of ethylene glycol and *OH radicals, which is critical for promoting C─C bond cleavage and subsequent dehydrogenation cascades. Using in-situ electrochemical infrared spectroscopy and theoretical calculations, the team identified the dominant reaction pathway: formate formation occurs primarily through C─C bond cleavage of glycolate followed by oxidation. Notably, CoNiOOH-Ni₃S₂/NF achieved an industrial-grade current density of 500 mA cm⁻² at an ultra-low potential of 1.45 V, with a Faradaic efficiency of 96.6% and formate yield of 3.14 mmol cm⁻² h⁻¹. The team also designed a practical two-electrode flow cell demonstrating robust activity and stability, converting 6.3 g PET into 4.97 g terephthalic acid and 4.83 g potassium formate. By precisely control key intermediate adsorption at active sites and unraveling reaction pathways, this study provides critical theoretical guidance for designing efficient non-noble metal heterointerfacial catalysts for electrochemical upcycling of PET plastics.
This research was supported by the National Natural Science Foundation of China, Shandong Provincial Natural Science Foundation Major Basic Research Program, and Basic Research Funds for Central Universities. Ocean University of China is the sole contributing institution. The first author of this paper is Jinyong Sun, a 2022 Ph.D. candidate.
Text/Figures: Jinyong Sun
