Mechanistic insight into the electrocatalytic hydrodechlorination reaction on palladium by a facet effect study

Abstract

Clarifying the reaction mechanism of electrocatalytic hydrodechlorination (EHDC) and identifying the catalytically favorable surface structure on Pd were crucial to maximize its power in remediating the chlorinated phenol pollutants. Herein, a study of the Pd facet-dependent EHDC performance toward 2,4-dichlorophenol (2,4-DCP) revealed the EHDC efficiency was governed by the H* yield on Pd at the potential above −0.80 V vs. Ag/AgCl, the phenol desorption at −0.80~−0.90 V and the intensity of the electrostatic field-induced repulsive force between 2,4-DCP and the cathode at the potential beyond −0.95 V. Further rationalization of the facet effect with the surface electronic/geometric structure of Pd demonstrated the density of active sites for H* generation and the d band center were two key structural properties. The Pd (110) with large density of active sites and the Pd (111) with a low d band center were the ideal facet to facilitate H* generation and phenol desorption, respectively.