Lignin ligand boosts Ni3+ species generation for biomass electrocatalytic oxidation

The electrocatalytic oxidation of biomass-derived platform molecules provides a sustainable pathway to high-value chemicals. The most commonly used Ni(OH) 2 catalyst, valued for its inherent redox activity, low cost, and structural tunability, however, suffers from insufficient active Ni 3+ species during the oxidation process. Herein, we developed an SL-Ni(OH) 2 catalyst with boosted Ni 3+ generation capability through a biomass-derived sulfonated lignin (SL) ligand regulation strategy. Leveraging the multifunctional structure of lignin, SL constructs an unsaturated Ni–O coordination environment on Ni(OH) 2 , which induces defect formation and Ni-site electronic modulation to synergistically reduce crystal field stability and weaken lattice hydroxyl O–H bond strength, thereby facilitating the generation of active Ni 3+ . The optimized SL-Ni(OH) 2 delivers a 29.90-fold enhancement in current density compared to pristine Ni(OH) 2 for the 5-hydroxymethylfurfural oxidation reaction (HMFOR), achieving a Faradaic efficiency > 99% for 2,5-furandicarboxylic acid (FDCA). Moreover, the assembled HMFOR electrolytic cell operates continuously for 100 h at a current density of 300 mA cm −2 with a > 90% FDCA yield, indicating excellent stability. This work demonstrates the potential of bio-derived polymers as sustainable ligands to tailor the electronic structures of electrocatalysts, turning underused lignin into a multi-site synergistic ligand and also offering a promising strategy for efficient biomass electrocatalytic oxidation.