Closed-loop electro-upcycling of PET waste into formate and hydrogen via self-supported NiCo2O4 spinel arrays

Abstract

The global accumulation of polyethylene terephthalate (PET) waste poses a severe environmental crisis and leads to severe underutilization of embedded carbon resources. In this work, a self-supported spinel NiCo2O4 electrocatalyst grown on nickel foam (NiCo2O4/NF) is developed for the electrochemical upcycling of PET-derived ethylene glycol (EG) into formate and hydrogen. The catalyst leverages a synergistic redox interaction between Ni and Co centers to enhance OH and EG adsorption, accelerate interfacial charge transfer, and steer selective C–C bond cleavage. Operando and theoretical analyses reveal that EG oxidation proceeds via a surface-confined pathway, where Ni3+ modulates redox dynamics and Co3+ facilitates C–C scission while suppressing overoxidation. This enables a high formate faradaic efficiency of 96.7% and an industrial-level current density of 400 mA cm−2 at 1.34 V. Notably, post-consumer PET bottles can be directly converted into potassium diformate, terephthalic acid, and H2 under mild alkaline conditions. A technoeconomic analysis reveals a net profit of $774.56 per ton PET processed, underscoring the feasibility and sustainability of this closed-loop strategy. This work provides a promising pathway for high-value chemical and energy recovery from plastic waste using earth-abundant, non-noble metal catalysts.

Graphical abstract: Closed-loop electro-upcycling of PET waste into formate and hydrogen via self-supported NiCo2O4 spinel arrays

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Article information

Article type
Paper
Submitted
21 Apr 2025
Accepted
23 Jul 2025
First published
24 Jul 2025

Green Chem., 2025, Advance Article

Closed-loop electro-upcycling of PET waste into formate and hydrogen via self-supported NiCo2O4 spinel arrays

M. Jiang, Y. Yang, Y. Wang, Y. Wang, M. Ratova and D. Wu, Green Chem., 2025, Advance Article , DOI: 10.1039/D5GC01993A

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