Electrochemical Upgrading of Waste Polylactic Acid Plastic for the Coproduction of C2 Chemicals and Green Hydrogen

Abstract

Tandem alkali-catalyzed hydrolysis and alkaline electrolysis have gradually become appealing avenues for the reformation of polyester plastics into high-value-added chemicals and green hydrogen with remarkable environmental and economic benefits. In this study, an electrochemical upcycling strategy was developed for the electrocatalytic oxidation of polylactic acid (PLA) hydrolysate into valued C2 chemicals (i.e., acetate) and hydrogen fuel using N, P-doped CuOx nanowires (NW) supported on nickel foam (NF) as the electrocatalyst. This 3D well-integrated catalyst was easily prepared from a Cu(OH)2 NW/NF precursor with Saccharomycetes as a green and safe P and N source. The electrocatalyst can efficiently catalyze the lactate monomer derived from the hydrolysis of PLA waste to acetate with high selectivity and exhibits a lower onset potential for the lactate oxidation reaction (LOR) than for water oxidation, saving 224 mV to deliver a current density of 30 mA/cm2. The experimental results reveal that the plausible pathway of the LOR on these CuOx NW involves oxidation and subsequent decarboxylation. Divalent copper species have been verified to be active sites for LOR via in situ Raman spectroscopy.