Tip-microenvironment engineering of Pd/CNT catalysts for enhanced electrochemical dechlorination

The atomic-local environment of catalytic sites plays a pivotal role in breaking robust C−Cl bonds during electrochemical dechlorination of organic chlorides (OCs). Herein, we propose a novel strategy to tailor the microstructure of carbon nanotubes (CNTs) via ball-milling, which induces controlled cleavage at crossing points to generate abundant tip structures. These high-curvature tips serve as preferential anchoring sites for Pd nanoparticles (Pd/BCNTs), enabling precise modulation of the local atomic environment. The optimized Pd/BCNTs electrocatalyst achieves exceptional performance, degrading 98.1 % of chloramphenicol (CAP) within 40 min and achieving ∼97.8 % dechlorination efficiency at −1.2 V vs. SCE, with a Faradaic efficiency for Cl − (FE Cl ) of 6.16 %. In contrast, conventional Pd/CNTs only removed 73.3 % of CAP with a lower FE Cl (3.32 %) and dechlorination rate (60.7 %). Mechanistic studies reveal that the tip-enhanced microenvironment boosts direct electron transfer (DET contribution: 60.30 % vs. 37.6 % for Pd/CNTs) and amplifies atomic hydrogen (H*) generation, as evidenced by a hydrogen adsorption charge (Q H ) of 75.40 mC that is 2.1 times higher than that of Pd/CNTs (35.91 mC). Finite element analysis (FEA) simulations confirm that the sharp tips concentrate electric fields and current density, accelerating water dissociation and interfacial electron transfer. This work advances the rational design of cost-effective electrocatalysts by leveraging microstructure engineering to synergize direct and indirect dechlorination pathways, offering a promising route for eliminating persistent organic pollutants.