Upcycling CO <sub>2</sub> and PET Waste: Ampere-Level Formate Electrosynthesis in an Integrated Electrolyzer
Xin‐Yao Yu, Hesamoddin Rabiee, Abhijit Dutta, Yaqiang Li, Zsolt Szakály, Soma Vesztergom, Lucas Warmuth, Alain Rieder, Peter Broekmann
Abstract
High Resolution Image Download MS PowerPoint Slide The rising accumulation of poly(ethylene terephthalate) (PET) waste and atmospheric CO 2 presents serious environmental and health challenges. Herein, we introduce a novel strategy for the simultaneous electrochemical upcycling of PET and CO 2 in a single integrated electrolyzer, enabling ampere-level coproduction of formate. Leveraging careful electrode design of three-dimensional Ni foam at the anode for ethylene glycol (EG, derived from PET hydrolysis) electrolysis, formate formation at 1.2 A cm –2 was achieved─outperforming all reported performances for non-noble metal catalysts. A Bi 2 O 2 CO 3 -based gas diffusion electrode (GDE) enabled the selective reduction of CO 2 (CO 2 RR) to formate at the cathode. By prioritizing enhanced reactant transport and electrode architecture beyond catalyst discovery, this integrated system achieved 100 h of stable operation at 0.50 A cm –2 with Faradaic efficiencies of 93.7% (anode) and 86.0% (cathode). Superior energy efficiency was achieved in the proposed membrane-free electrolyzer, with a cell voltage of 2.91 V at 1.0 A cm –2, reducing the input energy by 65% to ca. 0.1 kWh mol –1 . This study highlights the critical role of anodic reaction choices and electrode engineering strategies in developing integrated electrolyzers with superior performance metrics.