Electrochemical Upgrading of Lignin-Derived Phenolics via Vanadium Redox-Mediated Decoupling

Abstract

Electrochemical upgrading of biomass-derived phenolics represents a sustainable pathway to high-value chemicals yet remains hindered by mass transfer limitations when processing industrially relevant current densities and high-concentration substrates. Here, using phenol as a model, we report a redox-mediated strategy that spatially decouples electrode reactions from catalytic hydrogenation steps via a V3+/V2+ shuttle, effectively bypassing the interfacial diffusion barrier. By selecting a bimetallic PtRu/C catalyst, we synergistically optimize phenol activation on Ru sites and H* adsorption on Pt sites, achieving a balanced modulation of hydrogen coverage and substrate activation that effectively lowers the reaction barrier. This mediator-driven approach achieves a cyclohexanol Faradaic efficiency of 82.6% at 70 °C and −200 mA cm–2 in a dilute aqueous system. Separately, the biphasic configuration enables continuous processing of high-concentration phenol (>11 mol L–1 in the organic phase), while the system also demonstrates stable operation for over 310 h under continuous-flow conditions. This mediator-decoupling strategy is extended to the efficient hydrogenation of other lignin-derived platform molecules, and it establishes a scalable paradigm for electrified biomass conversion, thereby providing a practical approach toward advancing renewable-power-driven biomass valorization from laboratory electrosynthesis to industrial chemical manufacturing.