Photocatalytic Upgrading of Polylactic Acid Waste into Alanine under Mild Conditions

Abstract

Polylactic acid (PLA) has attracted increasing interest as a sustainable plastic because it can be degraded into CO2 and H2O in nature. However, this process is sluggish, and even worse, it is a CO2 emission and carbon resource waste process. Therefore, it is highly urgent to develop a novel strategy for recycling post‐consumer PLA to achieve a circular plastics economy. Herein, we report a one‐pot photoreforming route for the efficient and selective amination of PLA waste into value‐added alanine using CoP/CdS catalysts under mild conditions. Results show the alanine production rate can reach up to 2.4 mmol gcat‐1 h‐1, with a high selectivity (>75%) and excellent stability. Time‐resolved transient absorption spectra (TAS) reveal that CoP in‐situ grown on CdS can rapidly extract photogenerated electrons from CdS to accelerate proton reduction, favoring hole‐dominated PLA oxidation for the coproduction of alanine. This study offers an appealing way for the PLA waste upcycling and creates new opportunities for the green synthesis of amino acids.