Surfactant-enhanced Cuδ+ and induced electrostatic forces promote the electrocatalytic deuteron-dechlorination of trichloroacetic acid

Electrocatalytic deuteron-dechlorination of trichloroacetic acid (TCAA) in D₂O provides a green route to synthesize commercial acetic-d₃ acid-d (AA-d₄). Synthesizing AA-d₄ with a high Faradaic efficiency (FE) and reaction rate is highly challenging because of the difficult C-Cl bond deuteration of the 2-monochloroacetic-2,2-d₂ acid-d (MCAA-d₃) intermediate. Here, a quaternary ammonium salt surfactant-modified low-coordination copper electrocatalyst is designed, achieving TCAA-to-AA-d₄ with a 91% selectivity, 91% FE and 0.59 mmol h⁻¹ reaction rate at -100 mA cm⁻². Mechanistic and kinetic studies reveal that the surfactant enhances the adsorption of MCAA-d₃ through electrostatic forces and increases the electron deficiency of Cuδ+ sites, which accelerates electron transfer and promotes C-Cl bond activation, increasing the AA-d₄ selectivity. Surfactant-induced low D₂O coverage suppresses D₂ formation, improving the FE. AA-d₄ electrosynthesis (1.84 g) with a 30 mmol h⁻¹ reaction rate and 65% FE at 600 mA cm⁻² and deuterated drug applications demonstrate promising potential.