Unraveling the Impact of Oxygen Vacancy on Electrochemical Valorization of Polyester Over Spinel Oxides
Sailei Kang, Xuyun Guo, Dan Xing, Wenfang Yuan, Jian Shang, Valeria Nicolosi, Ning Zhang, Bocheng Qiu
Abstract
Abstract Electrochemical upcycling of end‐of‐life polyethylene terephthalate (PET) using renewable electricity offers a route to generate valuable chemicals while processing plastic wastes. However, it remains a huge challenge to design an electrocatalyst with reliable structure‐property relationships for PET valorization. Herein, spinel Co 3 O 4 with rich oxygen vacancies for improved activity toward formic acid (FA) production from PET hydrolysate is reported. Experimental investigations combined with theoretical calculations reveal that incorporation of V O into Co 3 O 4 not only promotes the generation of reactive hydroxyl species (OH * ) species at adjacent tetrahedral Co 2+ (Co2+ Td), but also induces an electronic structure transition from octahedral Co 3+ (Co3+ Oh) to octahedral Co 2+ (Co2+ Oh), which typically functions as highly‐active catalytic sites for ethylene glycol (EG) chemisorption. Moreover, the enlarged Co‐O covalency induced by V O facilitates the electron transfer from EG * to OH * via Co2+ Oh‐O‐Co2+ Td interaction and the following C─C bond cleavage via direct oxidation with a glyoxal intermediate pathway. As a result, the V O ‐Co 3 O 4 catalyst exhibits a high half‐cell activity for EG oxidation, with a Faradaic efficiency (91%) and productivity (1.02 mmol cm −2 h −1 ) of FA. Lastly, it is demonstrated that hundred gram‐scale formate crystals can be produced from the real‐world PET bottles via two‐electrode electroreforming, with a yield of 82%.