Terbium-doped cobalt-based metal–organic frameworks for electrocatalytic hydrogen production and polyethylene terephthalate plastic upcycling

Electrochemical conversion of polyethylene terephthalate (PET) into higher-value chemicals represents an ideal strategy for upcycling PET waste plastics. Herein, we have successfully synthesized self-supported Tb-doped Co-MOF nanosheets electrodes on nickel foam (TbCo-MOF/NF) and applied them to a PET hydrolysate electrolysis system. The incorporation of trace amounts of Tb can effectively modulate the interfacial electronic structure between Tb and Co, thereby optimizing the adsorption and activation of reactants and ultimately enhancing the electrochemical performance of the catalyst. During the electrochemical process, the TbCo-MOF nanosheets generates Tb-CoOOH and Tb-Co(OH)2 at the anode and cathode respectively, serving as truly active species that catalyze the PET hydrolysates oxidation reactions and hydrogen evolution reaction (HER). The TbCo-MOF/NF electrode requires an applied potential of 1.32 V for ethylene glycol oxidation reaction (EGOR) at 100 mA cm−2, while demonstrating an overpotential of 161 mV for HER at 10 mA cm−2 in a 1 M KOH solution. The PET hydrolysates-water co-electrolysis system based on TbCo-MOF/NF catalysts need 1.55 V of cell voltage to reach 10 mA cm−2 for co-production of hydrogen and formate. This study provides a feasible approach for optimizing the performance of electrochemically converting PET waste plastics into higher-value chemicals while simultaneously producing hydrogen.