Substrate Effects Govern Pd(111) Facet Formation for Efficient Electrochemical Hydrodechlorination

Palladium (Pd)-catalyzed electrochemical hydrodechlorination (EHDC) represents a promising approach for the remediation of chlorinated organic pollutants in wastewater. However, the role of conductive substrates in regulating the catalytic activity of Pd has been largely overlooked, as they are usually regarded as inert physical supports. Herein, we systematically investigate the role of four representative substrates (i.e., carbon cloth (CC), titanium sheet (TS), copper foam (CF), and nickel foam (NF)) in regulating the EHDC activity of Pd catalysts. Results show that Pd catalysts with comparable loadings exhibit pronounced substrate-dependent activity toward the dechlorination of various pollutants, following the order Pd/NF > Pd/CC > Pd/TS > Pd/CF. Mechanistic investigations reveal that this trend primarily arises from the substrate-controlled formation and stabilization of Pd(111) facets, governed by interfacial binding strength between Pd(111) and the underlying substrate. Stronger interfacial interactions promote the enrichment of highly active Pd(111) sites, which facilitate atomic hydrogen (H*) generation and thus enhance the EHDC performance. This study challenges the conventional perception of inert substrates and establishes substrate selection as a critical yet overlooked descriptor for optimizing Pd electrocatalysts in environmental remediation.