Hydroxyl-blocking lignin-derived carbon catalysts for selective and durable hydrogen peroxide electrosynthesis

Metal-free oxygen-functionalized carbon materials are promising electrocatalysts for selective hydrogen peroxide (H₂O₂) production via the two-electron oxygen reduction reaction (ORR). However, precisely controlling oxygen moieties while maintaining scalability remains challenging. Herein, we present a scalable and sustainable Friedel–Crafts reaction-assisted carbonization strategy that converts lignin into oxygen-tunable carbon catalysts for efficient H₂O₂ electrosynthesis. Electrochemical measurements reveal a strong correlation between carbonization temperature, oxygen speciation, and catalytic performance. Specifically, carbonyl and carboxyl groups enhance H₂O₂ selectivity, while hydroxyl groups suppress H₂O₂ formation by preferentially binding O* intermediates. Density functional theory corroborates these findings, indicating that carbonyl and carboxyl groups favor the two-electron pathway. Accordingly, selective blocking of hydroxyl groups achieves > 95 % H₂O₂ selectivity, a production rate of 575.5 mmol g_cat⁻¹ h⁻¹ at 0.4 V_RHE, and stable operation for 40 h. This renewable, low-cost platform couples mechanistic control with scalable synthesis, potentially enabling decentralized H₂O₂ generation in on-site disinfection and wastewater treatment.