Ligand-Intercalated MOFs Enable Reaction-Pathway Engineering in Biomass Electrooxidation via Steric and π-Electronic...

Controlling reaction pathways in electrocatalytic biomass upgrading remains challenging because mass transport, substrate adsorption, and elementary kinetics are intrinsically coupled within catalyst architectures. Here, we report a ligand-intercalation strategy that enables selective reaction-pathway engineering in layered metal-organic frameworks (MOFs) by decoupling effects of steric and electronic microenvironments. Aromatic dicarboxylate ligands with systematically varied length and π-electron density are intercalated into NiCo-based MOFs to create tunable interlayer nanochannels that independently regulate molecular diffusion and substrate-catalyst interactions. Expanded interlayer spacing enhances alcohol oxidation by improving mass transport and active-site accessibility, whereas π-electron-rich ligands selectively promote aldehyde oxidation through strengthened π-π interactions and accelerated hydrogen atom transfer (HAT), resulting in a shift of the rate-determining step (RDS) from a chemical to an electrochemical step. These orthogonal effects are quantitatively correlated with kinetic analysis, impedance spectroscopy, adsorption measurements, in situ spectroscopy, and density functional theory calculations. As a result, the optimized MOFs deliver low onset potentials, current densities up to 200 mA cm^-2, and near-quantitative Faradaic efficiencies and product yields in the selective oxidation of representative biomass substrates, 5-hydroxymethylfurfural and 2,5-diformylfuran. This work establishes ligand-intercalated MOFs as a versatile platform for microenvironment-driven reaction-pathway control in electrocatalytic biomass valorization.