Electrochemical Co-Production of Ammonia and Biodegradable Polymer Monomer Glycolic Acid via the Co-Electrolysis of Nitrate Wastewater and Waste Plastic

Electrochemical reformation of nitrate wastewater and poly(ethylene terephthalate) (PET) plastic waste into ammonia (NH3) and fine chemicals is a sustainable strategy for waste resource utilization. Herein, a co-production system of ammonia and glycolic acid (GA, degradable polymer monomer) is constructed by coupling nitrate reduction and ethylene glycol (EG, in PET hydrolysate) oxidation. Low-crystalline CoOOH (LC-CoOOH/CF) and Pd nanothorns (Pd NTs/NF) grown in situ on the metal foam substrates are employed as cathode and anode, respectively. The high density of amorphous regions in LC-CoOOH/CF enables enhanced nitrate adsorption and provides abundant active sites, ultimately leading to an ammonia Faradic efficiency (FE) of 97.38 ± 1.0% at −0.25 V vs reversible hydrogen electrode (RHE). Meanwhile, the unique nanothorn morphology endows the Pd NTs/NF with a high-curvature tip, triggering a tip effect (TE) to promote the highly selective oxidation of EG to GA. Furthermore, in the two-electrode coupling system, the co-production of NH3 and GA is operated at a low energy consumption (onset voltage: 0.5 V), much lower than the traditional nitrate electrolysis process (1.4 V). This study provides a method for the resource utilization of nitrate wastewater and PET plastic waste to co-produce NH3 and value-added chemicals.