Unraveling kinetics and mechanism of electrocatalytic hydrodechlorination of chlorinated PPCPs by nickel-cobalt metal organic framework supported palladium composite electrode

In this work, a nickel-cobalt bimetallic organic framework (NiCo-MOF) was introduced as an intermediate layer to synthesize a Pd/NiCo-MOF/Nickel foam composite electrode, which was applied for electrocatalytic hydrodechlorination (ECH) of chlorinated pharmaceuticals and personal care products (PPCPs). The introduction of the NiCo-MOF structure dramatically improved the catalytic activity compared with the common Pd/Nickel foam electrode. Combined with transmission electron microscope and X-ray absorption fine structure analysis, catalyst on Pd/NiCo-MOF/Nickel foam surface had smaller particle size. The removal of the Pd/NiCo-MOF/Nickel foam electrode for chloramphenicol (CAP) reached more than 95 % at 40 min, while the removal of the Pd/Nickel foam electrode was only approximately 55 %. In this study, the active atomic hydrogen (H*) adsorbed on the Pd and NiCo-MOF structures is the critical active species to remove chlorinated PPCPs by Pd/NiCo-MOF/Nickel foam electrode. Density functional theory (DFT) was used to calculate and investigate the adsorption strength of the composite electrode structure for CAP, the product and H*. This work provided a new method to achieve higher catalytic performance and reactivity operability and longevity of catalytic materials through the synergism of a NiCo-MOF interlayer with Pd particles.