Concerted and Selective Electrooxidation of Polyethylene-Terephthalate-Derived Alcohol to Glycolic Acid at an Industry-Level Current Density over a Pd-Ni(OH)2 Catalyst

Electro-reforming of Polyethylene-terephthalate-derived (PET-derived) ethylene glycol (EG) into fine chemicals and H-2 is an ideal solution to address severe plastic pollution. Here, we report the electrooxidation of EG to glycolic acid (GA) with a high Faraday efficiency and selectivity (>85 %) even at an industry-level current density (600 mA cm(-2) at 1.15 V vs. RHE) over a Pd-Ni(OH)(2) catalyst. Notably, stable electrolysis over 200 h can be achieved, outperforming all available Pd-based catalysts. Combined experimental and theoretical results reveal that 1) the OH* generation promoted by Ni(OH)(2) plays a critical role in facilitating EG-to-GA oxidation and removing poisonous carbonyl species, thereby achieving high activity and stability; 2) Pd with a downshifted d-band center and the oxophilic Ni can synergistically facilitate the rapid desorption and transfer of GA from the active Pd sites to the inactive Ni sites, avoiding over-oxidation and thus achieving high selectivity.

Automated summary

The electrooxidation of EG to GA with high efficiency and selectivity has been achieved using a Pd-Ni(OH)2 catalyst. The generation of OH* promoted by Ni(OH)2 plays a critical role in facilitating EG-to-GA oxidation and removing poisonous carbonyl species. The synergistic effect of Pd and Ni facilitates the rapid desorption and transfer of GA, avoiding over-oxidation and achieving high selectivity.