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

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 NH₃ 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-CH₂OH to GA. For nitrate reduction reaction (NO₃RR), a cooperative tandem mechanism between Cu sites facilitating the adsorption of NO₃⁻ and Pd promoting water dissociation enables the conversion of NO₃⁻ → NO₂⁻ → NH₃. In the flow-coupled two-electrode reactor using PdCuFeCoNi alloy electrode as both cathode and anode, the NO₃RR//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 NO₃RR system, indicating that this coupled system can simultaneously carry out the upgrading pathways of waste plastics and nitrate wastewater with economic viability.