Electrochemical Coupling of Lignin-Derived Phenolic Valorization and Green Hydrogen Production: A Minireview

Abstract

Lignin, the most abundant aromatic biopolymer in nature, is composed of phenylpropane units and represents a promising renewable source of aromatic chemicals for industrial applications. The valorization of lignin into bio-based chemicals through electrolyzers and upgrading technologies holds significant potential for developing environmentally and economically sustainable biorefineries. This minireview explores electrochemical hydrogen production coupled with alternative oxidation reactions that can replace the oxygen evolution reaction (OER), alongside discussions of lignin's structure, solubility, analytical methods, and the challenges of electrochemical depolymerization. Among various strategies, the electrocatalytic oxidation of lignin-derived phenolics has emerged as an environmentally benign approach, utilizing renewable electricity to drive reactions under mild and controlled conditions. Key topics include the development of efficient electrocatalysts for phenolic conversion and lignin-assisted proton exchange membrane electrolysis. Emphasis is placed on achieving high electrocatalyst activity, stability, and selectivity for effective lignin oxidation. Furthermore, challenges related to catalyst design, electrode materials, electrocatalytic systems, and process optimization are critically examined, along with potential pathways for improvement. This minireview highlights the opportunities and challenges in advancing electrocatalytic lignin valorization and provides perspectives on future developments in catalyst design and proton exchange membrane electrolysis integration to promote sustainable biomass utilization in accordance with green chemistry principles.