Tailoring Pd-Co/PPD/NS composite electrode for efficient electrocatalytic dechlorination of 4-chlorophenol

To address the challenges of slow bio-degradation and high toxicity of organic chlorophenols, some high-efficiency treatment strategies have been proposed. In this study, a high-performance palladium-cobalt/poly-(phenylenediamine)/nickel sponge (Pd-Co/PPD/NS) composite electrode was fabricated and utilized for electrocatalytic dechlorination of chlorophenol. Surface micromorphology, elemental distribution, and structural features of the electrodes were thoroughly investigated. Furthermore, effects of p-phenylenediamine concentration, chlorophenol concentration, cathode potential, and electrolyte content on electrocatalytic dechlorination efficiency were comprehensively studied. The presence of polyphenylene diamine greatly improved interfacial compatibility, thus promoting more Pd-Co particles deposition and creating additional catalytic active sites. Moreover, the larger conjugated structure in polyphenylene diamine facilitated electron transfer between electrode surface and electrolyte, resulting in high conductivity and substantially reducing charge transfer resistance. These enhancements greatly increased the electrocatalytic dechlorination efficiency. Under optimal reaction conditions, the dechlorination efficiency of the electrode reached 93.4 % with a mass activity of 25.3 min⁻¹g_pd⁻¹. Besides, the corresponding current efficiency also achieved about 24.6 %. Consequently, the Pd-Co/PPD/NS composite electrode we prepared also exhibited excellent recycling stability and high resistance to interference from negative ions.