Modulate adsorption via Co2+-O-Coδ+ asymmetric pairs toward efficient upcycling of plastic waste to commodity chemicals

Abstract

The conversion of polyethylene terephthalate waste into valuable bulk chemicals through electrochemical upcycling represents a viable strategy for waste valorization. The direct involvement of hydroxyl species is crucial for C-C bond cleavage during ethylene glycol oxidation in polyethylene terephthalate hydrolysate, thereby enhancing catalytic efficiency. However, excessive or competitive hydroxyl adsorption often suppresses ethylene glycol adsorption and activation, impeding the formation of key intermediates toward formic acid. Here we show a crystal boundary engineering strategy to construct an asymmetric Co2+-O-Coδ+ bridged electrocatalyst within cobalt oxides. This design integrates two catalytic sites: Co2+ sites preferentially facilitate hydroxyl adsorption, while Coδ+ sites exhibit enhanced affinity for ethylene glycol, thereby reducing the energy barrier for formic acid formation. Consequently, the Asy-Co2+-O-Coδ+ exhibits a high Faradaic efficiency of 96.12% and selectivity of 93.75%. It delivers an industrial-level current density of 1000 mA cm−2 under membrane electrode assembly conditions, with competitive stability over multiple polyethylene terephthalate hydrolysate electrolysis cycles. This study provides valuable insights for the design of advanced catalysts in the upcycling of polyethylene terephthalate waste. Electrochemical oxidation of ethylene glycol offers a sustainable route for upcycling polyethylene terephthalate waste. Here, the authors report a grain boundary-engineered asymmetric dual-site catalyst whose synergistic adsorption can be modulated, rendering it promising for plastic waste upcycling.