Probing unsuitability of ruthenium dioxide and constructing medium-entropy alloy oxide for polyethylene terephthalate electrocatalytic upcycling

Abstract

Environmental pollution and energy crisis are the most important problems all over the world. Polyethylene terephthalate (PET) is a widely used and difficult-to-degrade plastic that can be decomposed into terephthalic acid (PTA) and ethylene glycol (EG), and the EG can be electrocatalytically oxidized to high-value-added formic acid (FA). However, the commercial RuO₂ cannot support the EG oxidative reaction (EGOR) due to its strong absorption of intermediates and less exposed active sites, so the RuSb_0.92O_1.76 medium-entropy alloy oxide (MEAO) was constructed in this work. The RuSb_0.92O_1.76 fills up the O vacancy of RuO₂ and repairs the instability of RuO₂, and the lattice O in the RuSb_0.92O_1.76 promotes the EGOR by sacrificing itself to generate O vacancies. The RuSb_0.92O_1.76 shows a low EGOR potential of 1.13 V at 10 mA cm⁻², and a low hydrogen evolution reaction (HER) potential of 43 mV at 10 mA cm⁻². The RuSb_0.92O_1.76 shows a high Faradic efficiency (FE) of close to 100 % through the glycolaldehyde/GA pathway via the in situ ATR-IR spectroscopy. Density functional theory (DFT) reveals that RuSb_0.92O_1.76 has a moderate adsorption capacity for intermediates in the EGOR. This work provides a potential avenue for the MEAO catalysts in electrocatalytic plastic upcycling coupling hydrogen energy.