Sustainable Ammonia Electrosynthesis from Nitrate Wastewater Coupled to Electrocatalytic Upcycling of Polyethylene Terephthalate Plastic Waste

Abstract

Integrating the nitrate reduction reaction (NO₃RR) with polyethylene terephthalate (PET) hydrolysate oxidation to construct the nitrate/PET hydrolysate coelectrolysis system holds a great promise of realizing the simultaneous upcycling of nitrate wastewater and PET plastic waste, which, however, is still an almost untouched research area. Herein, we develop an ultralow content of Ru-incorporated Co-based metal-organic frameworks as a bifunctional precatalyst, which can be <i>in situ</i> reconstructed to Ru-Co(OH)₂ at the cathode and Ru-CoOOH at the anode under electrocatalytic environments, and function as real active catalysts for the NO₃RR and PET hydrolysate oxidation, respectively. With a two-electrode nitrate/PET hydrolysate coelectrolysis system, the current density of 50 mA cm^-2 is achieved at a cell voltage of only 1.53 V, realizing the simultaneous production of ammonia and formate at a lower energy consumption. This study provides a concept for the construction of coelectrolysis systems for upcycling of nitrate wastewater and PET plastic waste.