Electro-Reconstructed Transition Metal Electrodes for Coupled-Upgrading of Nitrate Pollution and Waste Poly(Ethylene Terephthalate) Plastics

Two unrelated forms of pollution, nitrate-containing wastewater and waste poly(ethylene terephthalate) (PET) plastics, can be converted into high-value chemicals by electrochemical reduction and oxidation reactions. Herein, coupled electrocatalysis is used for the co-production of ammonia (NH₃) and formic acid (FA) with a cathode formed by reconstructing Co on copper foam (R-Co/CF) as catalyst for nitrate reduction reaction (NO₃RR) and with an anode formed by reconstructing NiCo on nickel foam (R-NiCo/NF) as catalyst for ethylene glycol oxidation reaction (EGOR). The Faraday efficiency of the R-Co/CF cathode is 96.2% and that of R-NiCo/NF catalysts is 98.2%. By coupling NO₃RR and PET hydrolysate oxidation reaction, the cell voltage required at a current density of 50 mA cm⁻² is 202 mV lower than that of the traditional NO₃RR electrolytic system, indicating that electrocatalytic upcycling of PET plastics coupled with NO₃RR is an energy-saving and cost-effective strategy for producing value-added chemicals. Techno-economic analysis indicates that compared with a NO₃RR//OER system, the NO₃RR//PET hydrolysate oxidation system can save 2.8 × 10³ kW h⁻¹ in electricity and generate ≈6 900 USD in revenue per tonne of NH₃.