Sulfur-doped bimetallic phosphides with regulated intermediate adsorption for efficient polyethylene terephthalate upgrading

Abstract

Upgrading ethylene glycol (EG) derived from polyethylene terephthalate (PET) waste into valuable formic acid (FA) and H₂ offers a promising solution for plastic pollution. However, high-selectivity oxidation of EG to form FA is limited by the cleavage of the C–C bond with high bond energy during the ethylene glycol oxidation reaction (EGOR) process. To address this challenge, sulfur-doped bimetallic phosphide (NiFeP/FeSP) was designed using a microbial corrosion–phosphidation strategy. The constructed bifunctional NiFeP/FeSP electrocatalyst presents advanced EGOR coupled with hydrogen evolution reaction (HER) performance. The NiFeP/FeSP electrode can enable high-selectivity oxidation of EG to form FA, and requires only 1.38 V @10 mA cm⁻². Experimental and theoretical calculation results reveal that microbial-induced sulfur atom doping regulates the coordination environment of Ni, which can enhance the generation of Ni–O bonds and optimize the adsorption of H* intermediates, lowering the reaction energy barrier. Consequently, NiFeP/FeSP as a bifunctional electrode requires 1.52 V at 10 mA cm⁻² in the HER//EGOR system, which is 110 mV lower than that of the HER//oxygen evolution reaction system. These results suggest that the NiFeP/FeSP catalyst can efficiently convert PET hydrolysis products into high-value chemicals and hydrogen, which is of great significance for the development of sustainable environmental and clean energy technologies.