High-Performance Electrocatalysts of Potassium Lactate Oxidation for Hydrogen and Solid Potassium Acetate Production

Abstract

With the increasing use of polylactic acid (PLA), more attention is turning to its post-treatment. Current methods such as natural decomposition, composting, and incineration are limited by significant carbon dioxide emissions and resource waste. Here, an efficient electrocatalytic conversion approach is presented to transform PLA waste into high-value chemicals, particularly potassium acetate (AA-K). By combining experimental and theoretical calculation, a high-performance catalyst Ni(Co)OOH is developed, which exhibits a current density of 403 mA cm⁻² at 1.40 V (vs RHE) with 96% Faraday efficiency for AA-K in the electrooxidation of potassium lactate (LA-K, the product of PLA degradation in KOH). Through in situ spectroscopy techniques and density functional theory calculations, the structural regulation of the catalyst, and reaction pathways of the electrooxidation are elucidated. Further experiments demonstrate the superior catalytic performance of the Ni(Co)OOH catalyst in an industrial-scale tandem system. In 2 h of electrolysis, 320 g of PLA waste produces 232 L of H₂, yielding 1200 g of AA-K with 97% purity after neutralization and drying. The system demonstrates high conversion efficiency (approaching 97%) for diverse real PLA waste forms, including powder, cups, fibers, and cloth. This research provides a scalable and sustainable approach for PLA waste upcycling.