Hydrophobic interface engineering of nickel hydroxide for efficient electrocatalytic fatty alcohol oxidation coupled with hydrogen production

Electrocatalysis has emerged as a sustainable approach for the selective oxidation of fatty alcohols to fatty acids, circumventing the environmental concerns associated with conventional routes. However, the low aqueous solubility of hydrophobic fatty alcohols presents a major challenge. While nickel hydroxide (Ni(OH)₂) serves as a cost-effective catalyst for alcohol oxidation, its hydrophilic nature limits substrate accessibility and mass transport, causing sluggish kinetics and competing oxygen evolution. Herein, we propose a hydrophobic interface engineering strategy via co-electrodeposition of Ni(OH)₂ with polytetrafluoroethylene (PTFE), fabricating the composite electrode (ED-Ni(OH)₂-PTFE). The optimized electrode achieves 95 % Faradaic efficiency for octanoic acid at 1.5 V vs. RHE, with a production rate 2–3 times higher than pristine Ni(OH)₂. Mechanistic studies combining in situ Raman spectroscopy, fluorescence imaging, and coarse-grained molecular dynamics simulations reveal that PTFE selectively enriches octanol at the electrode-electrolyte interface by modulating interfacial hydrophobicity. A continuous-flow microreactor integrating anodic octanol oxidation with cathodic hydrogen evolution reduces cell voltage by ∼100 mV, achieving simultaneous fatty acid and hydrogen production. This work highlights the critical role of hydrophobic interfacial microenvironment design in organic electrosynthesis, offering a promising strategy for upgrading fatty alcohols under mild conditions.