•We developed a new Rh-catalyzed electrochemical hydrodefluorination (HDF) system.•Cathode material and solution pH were optimized with 4-fluorophenol as the substrate.•The HDF system realized the rapid degradation of 18 fluoroaromatics (FAs).•This study provides a new promising alternative for the treatment of FA pollutants.Many fluoroorganic compounds are toxic and persistent, and achieving their efficient degradation under mild conditions is currently a challenge. Herein, we developed a new electrochemical hydrodefluorination (HDF) system based on rhodium electrocatalyst for the degradation of fluoroaromatic (FA) pollutants. The HDF system realized the rapid degradation of 18 representative FAs to form nonfluorinated organics and F− under mild conditions (room temperature and pressure, water medium, air atmosphere, without the use of hazardous reagents). This study may provide a new promising alternative for the practical treatment of waste water containing FA pollutants.

Electrochemical reduction of 3,5,6-trichloropicolinic acid (3,5,6-T) at glassy carbon, Ni, Cu, and Ag cathodes in aqueous solutions at different pH values was investigated. Experiments suggest that the selectivity of the reduction strongly depends on the cathode materials used and the pH of the aqueous solutions. A high selectivity for the hydrodechlorination of 3,5,6-T to 3,5-dichloropicolinic acid (3,5-D) has been achieved exclusively at an activated Ag cathode and at pH 3: a selectivity of 95% at 42% conversion under potentiostatic mode and a selectivity of 89% at 88% conversion under intentiostatic mode. An explanation is proposed for this high selectivity.