Electronic structure and interfacial microenvironment engineering over the Ni(OH)2 nanoarray for boosted electrocatalytic upcycling of polyethylene terephthalate†

Abstract

Electrochemical reforming of polyethylene terephthalate (PET) plastic waste into value-added chemicals stands out as a green and sustainable way to mitigate plastic pollution. However, exploring high-performance electrocatalysts for PET upcycling remains a daunting challenge. Herein, the Ni(OH)₂ nanosheet array with surface engineering of adipic acid [NF/Ni(OH)₂-adp] is constructed to remarkably promote the PET-derived ethylene glycol oxidation reaction (EGOR) for value-added formate production. Experimental investigations and theoretical calculations unveil that surface adp functionalization can modulate the electronic structure with upshift of the d-band center, thereby promoting high-valent Ni³⁺ generation, strengthening the affinity toward EG, and decreasing the ΔG of rate-determining step, consequently boosting intrinsic catalytic activity. Impressively, adp modification can manipulate the interfacial microenvironment, endowing the electrode with superhydrophilic and oleophilic features, facilitating surface EG enrichment, thereby optimizing mass transfer kinetics. Benefitting from the aforementioned distinctive features, NF/Ni(OH)₂-adp exhibits prominent EGOR performance with an ultralow potential of 1.32 V vs. RHE to attain 10 mA cm⁻², a small Tafel slope of 30.2 mV dec⁻¹, and a commendable formate faradaic efficiency of 98.2%, favorably rivaling state-of-the-art ones. Additionally, with the NF/Ni(OH)₂-adp anode, a high-efficiency and durable two-electrode electrolyzer can be assembled to achieve PET upcycling coupled with H₂ generation. This research features simultaneous optimization of the electronic structure and interfacial microenvironment and provides a promising strategy to design advanced electrocatalysts for plastic waste upcycling in a sustainable and low-carbon mode.