Mechanistic Insights into the Role of β-Branching in Promoting Hydroxide-Mediated C–C Bond Cleavage for Electrocatalytic Bio-Alcohol Valorization

The oxidative cleavage of C–C bonds is a key reaction pathway in the electrocatalytic valorization of biomass-derived alcohols. However, the influence of molecular branching on this process remains poorly understood. Herein, we establish a nucleophilic hydroxide-mediated C–C cleavage mechanism on Ni(OH) 2 catalyst using isobutanol as a model β-branched primary alcohol. Combining 18 O isotope labeling with in situ mass spectrometry, we demonstrate that isobutyraldehyde is the key intermediate and that hydroxide anions (OH – ), rather than surface-adsorbed *OH, act as the active species driving C–C cleavage. Density functional theory (DFT) studies reveal that the β-branching creates steric hindrance that suppresses C–H dehydrogenation while simultaneously strengthening the van der Waals adsorption of the isobutyraldehyde intermediate. This enhanced adsorption lowers the energy barrier for nucleophilic attack by OH – . This work establishes a fundamental structure–reactivity relationship, offering a strategic blueprint for modulating reaction pathways in biomass upgrading.