Elucidating the Role of Single-Atom Pd for Electrocatalytic Hydrodechlorination.

In this study, we loaded Pd catalysts onto a reduced graphene oxide (rGO) support in an atomically dispersed fashion [i.e., Pd single-atom catalysts (SACs) on rGO or Pd/rGO] via a facile and scalable synthesis based on anchor-site and photoreduction techniques. The as-synthesized Pd/rGO significantly outperformed the Pd nanoparticle (Pd) counterparts in the electrocatalytic hydrodechlorination of chlorinated phenols. Downsizing Pd to Pd leads to a substantially higher Pd atomic efficiency (14 times that of Pd), remarkably reducing the cost for practical applications. The unique single-atom architecture of Pd additionally affects the desorption energy of the intermediate, suppressing the catalyst poisoning by Cl, which is a prevalent challenge with Pd. Characterization and experimental results demonstrate that the superior performance of Pd/rGO originates from (1) enhanced interfacial electron transfer through Pd-O bonds due to the electronic metal-support interaction and (2) increased atomic H (H*) utilization efficiency by inhibiting H evolution on Pd. This work presents an important example of how the unique geometric and electronic structure of SACs can tune their catalytic performance toward beneficial use in environmental remediation applications.