Precursor-engineered lignin-derived Co/N-doped carbon for high-efficiency electrocatalytic HMF oxidation: The critical role of pretreatment history

This study investigated the electrocatalytic oxidative process of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) using Co/N-doped carbon catalysts derived from lignin subjected to different pretreatment methods, including enzymatic hydrolysis lignin (EHL), alkali lignin (AL), and kraft lignin (KL). The EHL-derived catalyst exhibited superior activity, achieving a current density of 110 mA cm −2 at 1.5 V vs. RHE along with 98% HMF conversion, 99.02% FDCA selectivity, and 98.4% Faradaic efficiency (FE). Structural characterizations and theoretical calculations revealed that the preserved aromatic framework of EHL promoted the formation of atomically dispersed Co–N x active sites and facilitated efficient HMF adsorption. The computational results further demonstrated that the optimized electronic structure of the Co-N x sites reduced the activation energy for the rate-determining step. This work demonstrated a direct correlation between the pretreatment history of lignin and its electrocatalytic performance, offering a precursor-based design strategy for efficient HMF electrooxidation.