Electrocatalytic hydrodehalogenation of pentachlorophenol at palladized multiwalled carbon nanotubes electrode

The palladized multiwalled carbon nanotubes (MWCNTs) electrode was prepared for electrocatalytic hydrodehalogenation (HDH) of pentachlorophenol (PCP). The MWCNTs grew directly on graphite by chemical vapor deposition (CVD), and Pd was loaded on MWCNTs with electrochemical deposition. The MWCNTs and Pd catalyst were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption (BET surface area) and X-ray diffraction (XRD). The diameter and surface area of MWCNTs were 40–60 nm and 54 m2/g, respectively. The particle size of Pd was about 13 nm. Electrocatalytic HDH of PCP by Pd/MWCNTs/graphite electrode was performed in H2SO4 anolyte separated by Nafion membrane H-cell. The complete degradation of 0.15 mM PCP was achieved at 180 min with the dechlorination efficiency being 96%, and the yield of cyclohexanone was 60% (7.4% current efficiency). Compared with the Pd/graphite electrode, the Pd/MWCNTs/graphite electrode exhibited higher dechlorination efficiency and hydrogenation activity of the carbon–carbon double bond for PCP. The effects of anolyte and potential on HDH, electrode stability were also investigated.