Pd nanoparticles supported on microflower NiMOF modified roughed nickel foam with the enhanced active site for electrochemical dechlorination of trichloroacetic acid

Abstract

Electrocatalytic hydrodechlorination (ECH) has been considered as an effective method to convert refractory chlorinated organics into biodegradable chlorine-free organics under mild conditions. In this work, a composite electrode of Pd/NiMOF/roughed nickel foam (Pd/NiMOF/RNF) with excellent dechlorination performance was prepared by electrodeposition of Pd nanoparticles on the flower-shaped NiMOF interlayer grown in-situ. Benefiting from the high specific surface area of NiMOF structure and excellent dispersion of Pd facilitated, the Pd/NiMOF/RNF offered abundant active hydrogen and larger open channels for the easy diffusion of reactants and products in the electrochemical dechlorination process. 97% of 6 μmol/L trichloroacetic acid (TCAA) was dechlorinated at a cathodic potential of −1.2 V within 90 min. The corresponding palladium mass activity was calculated to be 0.39 μg min⁻¹ cm⁻² mg⁻¹ Pd, which was approximately 3.5 times greater than other report on ECH cathode. Moreover, the Pd/NiMOF/RNF cathode remained stable even after five consecutive cycle tests. Toxic assessment results indicated that the dechlorination process was beneficial to the detoxification of TCAA at the end of reaction. The hydrodechlorination mechanism of TCAA was proposed by density functional theory (DFT) analysis and electrochemical characterization on the Pd/NiMOF/RNF electrode. The findings of this study have the potential to contribute to the development of electrocatalytic treatment methods for chlorinated organic compounds in drinking water.