Mechanistic Insight into the Role of Bi in Bi-rich PdBi Alloy Structure for Promoting Electrocatalytic Upcycling of Polyethylene Terephthalate Plastics into Formate

To upcycle polyethylene terephthalate (PET) plastics into high-value-added chemicals and fuels, it is necessary to design efficient and durable electrocatalysts for the ethylene glycol oxidation reaction (EGOR). Different from Pd-rich structures, here, a novel reverse design strategy, in which a Bi-rich PdBi alloy structure supported on carbon nanotubes (PdBi/CNT), is proposed. The obtained Pd1Bi2/CNT catalyst exhibits exceptional mass activity (14.97 A mgPd–1) and specific activity (142.4 mA cm–2) toward EGOR, outperforming monometallic Pd/CNT and other PdBi/CNT catalysts. Systematic characterization reveals that the cooperation of Bi with Pd induces lattice expansion, optimizes electronic structure via electron-transfer from Bi to Pd, and downshifts the d-band center, which further weakens intermediate adsorption and enhances CO antipoisoning ability. Especially, in situ FTIR, in situ EIS, and DFT calculations demonstrate that designing a Bi-rich PdBi alloy structure could lower the energy barrier for ethylene glycol dehydrogenation, promote the formation of *OH generation, and accelerate EGOR kinetics. Notably, the best Pd1Bi2/CNT catalyst achieves high Faradaic efficiency of 71.4% for formate production from PET hydrolysate cooperating with terephthalic acid recovery. This work provides a good inspiration for designing Bi-rich alloy structures with tailored electronic properties for the conversion of PET plastics.