Achieving high performance for electrocatalytic dechlorination with magnetic Pd/CoFe2O4 particle electrodes

Highlights: • Magnetic Pd/CoFe₂O₄ nanoparticles were prepared by chemical deposition. • Metallic Pd was actively interacted with CoFe₂O_4. • Pd/CoFe₂O₄ particle electrodes in the 3D reactor were effective in removing 2,4-DCP. • Alkaline condition was favorable for achieving increased dechlorination performance. • These catalysts exhibit attractive stability and recyclability in long-term use. Moveable catalysts in a three-dimensional (3D) electrochemical reactor offer benefits for pollutant dechlorination because of increased active sites and mass transfer, but they suffer from difficulties in catalyst recovery. Herein, we demonstrate that magnetic Pd/CoFe₂O₄ catalysts are highly active, durable, and recyclable when used in the electrochemical dechlorination of 2,4-dichlorophenol (2,4-DCP). Highly dispersed nano-sized Pd/CoFe₂O₄ catalysts were successfully synthesized using an easy chemical deposition method. Tests on the effects of the initial solution pH showed that the alkaline condition was favorable for achieving increased dechlorination performance in terms of increased reaction rate and higher current efficiency. Greater amounts of surface-adsorbed atomic H (H_ads*) formed and Pd with an electron-rich state as a consequence of metal-support interaction under the alkaline condition may play important roles in the effectiveness. The Pd/CoFe₂O₄ particle electrodes in the 3D reactor were effective in removing 2,4-DCP with different concentrations. Notably, at a current density of 2.50 mA cm⁻², 200 mg L⁻¹ 2,4-DCP can be dechlorinated to phenol within 30 min with current efficiency of 64.4%. The findings demonstrate that magnetic Pd/CoFe₂O₄ catalysts hold distinct promise for application in the 3D electrochemical dechlorination process.