Manipulating the Interfacial Hydrophobic Microenvironment via Electrolyte Engineering Promotes Electrocatalytic Fatty Alcohol Oxidation Coupled with Hydrogen Production.

The selective oxidation of fatty alcohols to fatty acids represents a pivotal transformation in organic synthesis. Traditional methods often require harsh conditions and environmentally harmful oxidants or solvents. Electrocatalytic oxidation emerges as a promising green alternative, enabling mild oxidation in aqueous media and concurrent energy-efficient hydrogen production at the cathode. However, the poor solubility of fatty alcohols in water poses a significant challenge, reducing the reactant availability at the electrode surface, thereby hindering mass transfer and overall reaction rates. Herein, we develop an electrolyte engineering strategy that incorporates cetyltrimethylammonium hydroxide (CTAOH) as an additive. This strategy significantly enhances the oxidation current density of fatty alcohols as well as the production rate of fatty acids on a gold electrocatalyst. Through a mechanistic investigation combining experimental evidence from a quartz crystal microbalance (QCM) and in situ attenuated total reflectance surface-enhanced infrared spectroscopy (ATR-SEIRAS) with molecular dynamics (MD) simulations, we confirm that the preferential adsorption of CTAOH creates a hydrophobic interfacial microenvironment at the anode, promoting the enrichment of reactant at the electrode-electrolyte interface. This work highlights the significance of interfacial hydrophobicity modulation in boosting aqueous-phase electrocatalytic oxidation, paving the way for more efficient electrocatalytic transformations involving water-insoluble reactants.