Electrocatalytic Valorization of Poly(ethylene terephthalate) Plastic and CO₂ for Simultaneous Production of Formic Acid

Abstract

The electro-reforming of polymer plastic waste and CO2 has the merits for producing value-added chemicals and alleviating environmental pollution. Herein, we report an electrocatalytic integrating strategy for efficient valorization of poly­(ethylene terephthalate) (PET) plastic and CO2 to simultaneously produce formic acid at both anode and cathode. The NiCo2O4 electrocatalyst displays a high Faradaic efficiency of 90% for formic acid production, which indicates the excellent selectivity for PET hydrolysate oxidation. By coupling the PET hydrolysate oxidation reaction with the CO2 reduction reaction, the assembled electrolyzer exhibits a low cell voltage of 1.55 V to drive the integrated two half-reactions. Furthermore, a high Faradaic efficiency of 155% for formic acid can be achieved at a cell voltage of 1.90 V. This study suggests that electrocatalytic valorization of PET plastic coupling with CO2 reduction could be an energy-efficient and economically viable strategy to realize the production of value-added chemicals.

A general electrochemical strategy for upcycling polyester plastics into added-value chemicals by a CuCo2O4catalyst

“…Duan et al reported that EG can be converted into isolable potassium diformate using a CoNi 0.25 P electrocatalyst; 28 and Zhao et al demonstrated that electrocatalysts (CuO and NiCo 2 O 4 ) can catalyze EG into formate. 29,30 Our group also reported that EG can be converted into carbonate by a Pd-based catalyst. 27 However, Pd-based catalysts are relatively expensive and afflicted with poor electrochemical stability.…”

“…25,26 Recently, electrochemical reforming of PET into addedvalue and separable chemicals has been proposed. [27][28][29][30] PET can be hydrolyzed into terephthalate (TPA-K) and ethylene glycol (EG) monomers when catalyzed under basic conditions. Unfortunately, the subsequent separation of the products requires equipment for a more demanding distillation process and energy input due to the high boiling point (197.6 °C), viscosity (19.8 mPa s at 20 °C) and excellent water solubility of EG.…”

Plastic Waste Valorization by Leveraging Multidisciplinary Catalytic Technologies

“…This work showcases the processing design for plastic upcycling and displays structure–catalytic activity correlation studies by leveraging electrocatalytic techniques in electrooxidation of biomass derivatives. Further development of advanced electrocatalysts and integration with upstream photovoltaic generation are currently in progress. − Moreover, integrating anodic plastic reclamation with CO 2 reduction shows the merits of increasing economic value of products and alleviating environmental pollution …”

“…Electrocatalytic oxidative valorization of PET waste hydrolysate has also been integrated with CO 2 reduction reactions (CO 2 RRs) toward simultaneous production of formic acid at both the anode and cathode through the following equations: By the use of a low-cost NiCo 2 O 4 nanowire on carbon fiber paper as the anodic catalyst and a SnO 2 nanosheet on carbon cloth as the cathodic catalyst, this reaction system can trigger electrocatalytic PET valorization and CO 2 RR in one system. A homemade electrolyzer was made that achieved a total FE for formic acid of 155%.…”

“…However, many chemical methods still suffer from harsh reaction conditions (e.g., high temperature and pressure), limiting their application in an environmentally benign fashion. By contrast, electrochemical, photochemical, and biological technologies offer the opportunity to operate under mild conditions, which are promising complements or alternatives to conventional chemical processes. ,,,, However, these technologies are still in the nascent stage, and there is plenty of room to improve the productivity, selectivity, and scalability. Remarkably, more efforts are increasingly being devoted to this field in recent years, delivering innovative processes that show great potential to convert plastic waste to valuable products.…”