Designing an Electron-Deficient Pd/NiCo2O4 Bifunctional Electrocatalyst with an Enhanced Hydrodechlorination Activity to Reduce the Consumption of Pd.

Reducing the Pd loading on electrodes is critical in the electrocatalytic hydrodechlorination (EHDC) of chlorinated organic compounds (COCs). The EHDC reaction of COCs on Pd involves three steps: H* formation, H* adsorption, and dechlorination. It has been established that the initial hydrogen evolution reaction (HER) occurs on Pd0 and the dechlorination steps occur on Pd2+. A strategy is proposed to design new electrodes by adding a reducible HER-active interlayer to replace Pd0, fulfilling the responsibility of producing hydrogen, and to facilitate the formation of more Pd2+ for following C-Cl bond cleavage. Keeping the atomic hydrogen adsorption energy on the Pd/interlayer similar to that on pure Pd is also necessary for H* adsorption as well as to maintain a high EHDC activity. For the first time, the NiCo2O4-interlayer-modified Pd/Ni-foam electrode was applied in the EHDC of COCs, which enhanced the EHDC efficiency to 100% within 90 min and reduced 88.6% of Pd consumption. The Pd/NiCo2O4/Ni-foam electrode with enhanced EHDC activity was also observed with almost 100% product selectivity and good stability. A synergistic mechanism is proposed for the enhanced EHDC activity on the Pd/NiCo2O4/Ni-foam. This work offers a simple and useful strategy to design robust electrocatalysts for the EHDC of COCs.