Wood Carbon‐Enabled Metal Vacancies Drive Electrochemical Hydrogenation: Selective CO ₂ Methanation and Beyond

Electrochemical hydrogenation (ECH) demands precise control over multistep pathways, yet developing selective electrocatalysts remains challenging. Herein, we utilize hierarchical carbonized wood (CW) as a sustainable catalytic support to drive deep ECH reactions. By anchoring ZnO nanosheets within CW's microchannels via facile calcination-impregnation, we engineered ZnO/CW catalysts enriched with Zn and O vacancies that promote CO₂ deep hydrogenation to CH₄. By coupling ZnO/CW and 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim]PF₆)/acetonitrile electrolyte, the system exhibited high CH₄ Faradaic efficiency (FE) of 72.9% at -1.34 V vs. SCE. This performance fundamentally diverged from conventional ZnO/carbon paper (ZnO/CP) which terminates at CO production (62.3% FE), showcasing support-driven pathway redirection. Both experimental and theoretical investigations revealed that CW's porous framework facilitates mass transport while Zn vacancies lower the energy barrier in the CH₄ pathway. The platform's versatility extended to oxalic acid upgrading, where SnO₂/CW achieved selective ECH of oxalic acid to glycolic acid in identical electrolytes. This work establishes biomass-derived defect-rich interfaces as sustainable design paradigm for multistep electrocatalytic hydrogenations.