Pd Metal-Doping Modulated CuxO-Based Porous Carbon Electrodes: Elucidating the Kinetics and Mechanism of Enhanced Trichloroacetic Acid Dechlorination

Haloacetic acids (HAAs), which are characterized by their persistence in tap water, are major contributors to the carcinogenic risk posed by disinfection byproducts (DBPs). This study introduces a Pd/Cu x O porous carbon composite electrode, synthesized via a metal-doping modulation strategy and immobilized on a steel electrode for the electrocatalytic dechlorination of trichloroacetic acid (TCAA). The Pd/Cu x O/St electrode demonstrated outstanding dechlorination efficiency, achieving up to 95.2% TCAA removal, surpassing that of other experimental transition metals. Material characterization confirmed the successful formation of a Pd-Cu x O heterostructure on the Pd/Cu x O/St composite electrode. Electrochemical analysis revealed that the optimized Pd/Cu x O/St system displayed a significantly higher current density and enhanced reaction kinetics than their undoped counterparts. The optimal mass ratio of Pd/Cu x O for doping was determined to be 0.075:1, achieving TCAA removal efficiency of 95.2%. Our Pd/Cu x O/St electrode combined rapid kinetics, dual-pathway mechanisms, and metal-doping synergy to efficiently convert the persistent and toxic DBPs into harmless products. Quenching experiments with tert-butanol and EDTA-2Na identified atomic hydrogen (H*), Cu, and Pd ions as the dominant active species, leading to the conversion of TCAA to less toxic acetic acid. This work not only advances TCAA dechlorination technology but also provides vital insights for developing effective end-of-pipe treatments for DBPs, a significant step towards safer drinking water.