ZIF-67 Nanoarrays Derived Pd Hybrid Catalyst with Improved Mass Activity and Current Efficiency for Electrocatalytic Reductive Dechlorination of 2,4-Dichlorophenol

Abstract

Pd-based catalysts are famous in the electrocatalytic reductive dichlorination (ERD) of chlorinated organic compounds (COCs) in aqueous media, while their high cost and low current efficiency hamper the large-scale application. This study presents a hierarchically structured nanoarray electrode, Pd/Co/CuCoOxHy/NF, synthesized for efficient electrocatalytic dechlorination of 2,4-dichlorophenol. 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 gPd-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. The work demonstrates a viable design approach for high-performance, current-efficient palladium-based electrocatalysts in water purification applications