Ultra-low-loading Pd nanocrystals modified Ni foam electrode for efficient electrochemical hydrodechlorination

Pd nanocrystals modified Ni foam electrode (Pd NCs/Ni) with Pd loading of 12.5 mu g cm(-2) was prepared via electrodeposition and exhibited higher mass activity in the electrochemical hydrodechlorination. With the assistance of polyvinylpyrrolidone and bromide ion, Pd nanocrystals with abundant catalytic sites were uniformly anchored on both the inner and surfaces of the Ni foam. Six chlorophenols were rapidly dechlorinated to phenol using Pd NCs/Ni with high conversion (> 98%) and selectivity (similar to 100%). Pd NCs/Ni showed broad applicability to various reaction conditions and maintained stable activity over 12 consecutive cycles. The electrochemical hydrodechlorination follows the indirect dechlorination mechanism. Hydrogenolysis between adsorbed H and chlorophenols is the rate-controlling step. Low coordination Pd atoms on the faces of Pd (220) and Pd (311) are the main catalytic sites. The study provides a valuable insight of high performance and low cost Pd modified electrode and its catalytic mechanism in electrochemical hydrodechlorination.