Coupled waste polyester plastics and nitrate-containing wastewater upgrading via high-entropy-like PdCu-based multi-component alloy

Self-supported PdCu-based multi-component alloys bifunctional electrodes were fabricated by electrodeposition. • A paired electrochemical system realized upcycling of waste PET plastic and nitrate-containing wastewater. • The high-entropy effect regulated the electronic structure of PdCu alloys and enhanced the catalytic activity. With the continuous decrease in the cost of renewable electricity, the electrocatalytic coupling systems provide a sustainable strategy for treating Poly(ethylene terephthalate) (PET) waste plastic and nitrate-polluted wastewater. However, their practical application depends on bifunctional electrocatalysts with high selectivity and stability. Herein, a self-supported high-entropy-like PdCu-based multi-component alloy (PdCuFeCoNi) electrode is fabricated via a one-step electrodeposition, achieving Faradaic efficiencies of 92.1% for NH 3 and 96.8% for GA production. The incorporation of Fe, Co, and Ni induces a high-entropy-like effect that regulates the electronic structure of the PdCu-based multi-component alloy, downshifts the d-band center, enhances the adsorption of *EG and *OH, and promotes the conversion of the key intermediate *CO-CH 2 OH to GA. For nitrate reduction reaction (NO 3 RR), a cooperative tandem mechanism between Cu sites facilitating the adsorption of NO 3 − and Pd promoting water dissociation enables the conversion of NO 3 −  → NO 2 −  → NH 3 . In the flow-coupled two-electrode reactor using PdCuFeCoNi alloy electrode as both cathode and anode, the NO 3 RR//EGOR system requires a cell voltage of only 0.52 V to achieve 100 mA cm −2 , which is 1.09 V lower than that of traditional NO 3 RR system, indicating that this coupled system can simultaneously carry out the upgrading pathways of waste plastics and nitrate wastewater with economic viability. The high-entropy-like effect regulates the electronic structure of PdCu alloy electrodes, enhancing the reaction kinetics of multi-component PdCu-based alloys in the electrochemical upcycling of PET plastic waste and nitrate wastewater. Download: Download high-res image (153KB) Download: Download full-size image