ZIF-67 nanoarray derived Pd hybrid catalyst with improved mass activity and current efficiency for the electrocatalytic reductive dechlorination of 2,4-dichlorophenol

Abstract

Pd-based catalysts are well-known for their role in the electrocatalytic reductive dichlorination (ERD) of chlorinated organic compounds (COCs) in aqueous media, however, their high cost and low current efficiency hamper their large-scale application. This study presents a hierarchically structured nanoarray electrode, Pd/Co/CuCoO_xH_y/NF, synthesized for efficient electrocatalytic dechlorination of 2,4-dichlorophenol (2,4-DCP). With a sequential synthesis strategy, the catalyst features Pd and Co nanoparticles uniformly dispersed on a Cu-doped cobalt oxide/hydroxide nanosheet scaffold. It delivers a high 2,4-DCP degradation efficiency of 91.5% within 2 hours at −0.85 V (vs. SCE), accompanied by an exceptional current efficiency of 60.7%, a competitive mass activity of 29.17 min⁻¹ g_Pd⁻¹, and robust operational stability over 10 repeated cycles. Mechanistic studies indicate a concerted direct electron transfer pathway as the predominant reaction route, distinct from the indirect route observed on Pd/NF. This behavior is attributed to the tailored electronic structure of the Pd active sites, engineered by the strong Co–Pd interactions, coupled with the electrode's porous architecture that ensures efficient mass and charge transport. This study demonstrates a viable design approach for high-performance, current-efficient palladium-based electrocatalysts for water purification applications.