Paired electrochemical synthesis of glycolic acid and ammonia from polyester and nitrate sewage

Abstract

Electrochemical upcycling of nitrate (NO₃⁻) wastewater to ammonia offers a sustainable route for reclaiming nitrogen resources from waste. However, its practical implementation still faces substantial obstacles, including high energy input and limited selectivity. Here, we report a paired electrochemical system that combines the anodic oxidation of polyethylene terephthalate (PET) hydrolysate, specifically its ethylene glycol (EG) monomer, to glycolic acid (GA) with the cathodic reduction of NO₃⁻ to ammonia. All of this is made possible by the discovery of a PdCu alloy anode and a CuCo alloy cathode. Built upon experimental demonstration and a theoretical understanding of the improved CO resistance on the PdCu alloy for EG oxidation, as well as the synergy between Cu and Co for NO₃⁻ reduction, our paired system enables the efficient co-production of GA and ammonia from PET hydrolysate and NO₃⁻-containing wastewater. This conceptual design of paired electrochemistry provides an intriguing way to synthesize high-value chemicals from waste resources.