Co(PO₃)₂@CoP Heterojunction in CoPO/GC/NF Nanoarrays Modulate Proton Hydrogen-Promoted Electrocatalytic Hydrodechlorination

Cobalt phosphide has received much attention as an efficient catalyst for electrocatalytic hydrodechlorination (EHDC). However, the active species proton hydrogen (H*) is consumed by the hydrogen evolution reaction (HER). Herein, we report a crystal regulation strategy for cobalt phosphate/graphitic nanocarbon/nickel foam (CoPO/GC/NF) catalysts applied for the EHDC of 2,4-dichlorophenoxyacetic acid (2,4-D). Characterization revealed that during the high-temperature phosphatization process, CoPO/GC/NF catalysts developed Co(PO₃)₂@CoP heterojunctions, enhancing charge transfer at the electrolyte-catalyst interface and water dissociation. The interaction between Co(PO₃)₂ and CoP induced the reconstitution of CoP into the Co-OH species, which facilitated the production of H* by accelerating the Volmer step, enhancing EHDC activity. Furthermore, Co(PO₃)₂ species improve the catalyst tolerance, with CoPO/GC/NF(450) maintaining over 71% yield of phenoxyacetic acid (PA) in continuous testing for up to 80 h under high-salt conditions. This work clarifies the surface transformation process of CoP/GC/NF during hydrodechlorination and demonstrates great potential for chlorophenol wastewater remediation.