Chromium‐Modified Nickel Sulfide Catalysts Enable Energy‐Efficient Electrochemical Polyethylene Terephthalate Upcycling

Despite recent stunning progress in electrocatalytic valorization of plastics, it remains a huge challenge to develop highly active electrocatalysts for achieving industrial‐level current density. Herein, a flocculent chromium‐modified nickel sulfide (Cr‐Ni3S2‐Ni(OH)2/NF) immobilizing on nickel foam and scrutinize its electrocatalytic activity for oxidation of ethylene glycol monomers (EOR) of polyethylene terephthalate (PET) is crafted. The Cr‐Ni3S2‐Ni(OH)2/NF catalyst facilitates efficient formate production at an industrial‐level current density of 1200 mA cm−2, requiring a record low potential of 1.561 V (vs. RHE). A series of in‐situ spectroscopy in conjunction with theoretical calculations substantiates that the high activity of the catalyst originates from the regulated d‐band center of Ni by Cr and S species. Hybrid electrosynthesis systems coupling EOR and cathodic CO2 or H2O reduction reaction (CO2RR or HER) are subsequently assembled. When reaching 400 mA cm−2, CO2RR//EOR electrolyzer enables coproduction of formate at an impressively low cell voltage of 2.694 V, avoiding ion‐exchange membrane and product crossover. Rigorous techno‐economic evaluation reveals that the attractive profitability of these two electrosynthesis routes reverses the long‐term dilemma of negative profits. This work paves a green and sustainable avenue toward the valorization of low‐grade carbon resources.