Photo-electrochemical synergistic construction of oxygen vacancy-Pd interfaces for efficient electrocatalytic hydrodechlorination

Photo-Electrochemical Synergistic Strategy for Constructing Oxygen-Vacancy-Rich Pd/CeO2/NF. • Ultralow Pd loading delivers an exceptional mass activity of 362.57 min-1 gPd-1，complete 4-CP removal in 120 min, and outstanding durability (>95%, 10 cycles). • SMSI induces an oxygen-vacancy-rich CeO2 surface that promotes water activation to generate abundant H* species. • DFT calculations rationalize the enhanced performance: interfacial charge transfer (~0.52 e) from Pd to CeO2 optimizes ΔGH* at the Pd/CeO2 interface, validating the spatially decoupled hydrogen spillover mechanism. Chlorinated organic compounds (COCs) pose severe threats to ecological systems and human health owing to their high toxicity and recalcitrance to degradation. Electrocatalytic hydrodechlorination (EHDC) has emerged as a promising remediation strategy, as it directly drives C Cl bond cleavage via cathodic electron transfer without requiring exogenous chemical reductants and operates under mild conditions. Palladium (Pd), with its unique d-electron configuration, exhibits a near-optimal hydrogen adsorption free energy and is therefore well-suited for this reaction. However, conventional Pd catalysts suffer from low atomic utilization efficiency and severe competing hydrogen evolution reaction (HER). To address these limitations, a photo-assisted electrodeposition strategy was developed to simultaneously achieve high dispersion of Pd active sites and precise regulation of interfacial electronic structure. Ultraviolet irradiation of the CeO 2 support generated photoelectrons that induced in-situ reduction and anchoring of Pd precursors at oxygen vacancy defect sites, effectively suppressing Pd migration and aggregation. Consequently, highly dispersed Pd nanoparticles (~4.65 nm) were obtained at an ultralow Pd loading of 0.1326 wt%, maximizing precious-metal atom utilization efficiency. Furthermore, strong metal–support interactions (SMSI) between Pd and CeO 2 induced directional interfacial electron transfer from Pd to CeO 2 (~0.52 e), creating an electron-rich Pd-CeO 2 interface. This electronic reconstruction precisely modulated the hydrogen adsorption free energy and effectively suppressed excessive H* accumulation on Pd, thereby mitigating the competing HER. This work provides a new interfacial engineering strategy for designing EHDC catalysts with low precious-metal loading and high atom utilization efficiency, while elucidating the mechanism by which oxygen vacancies regulate hydrogen spillover for enhanced catalytic performance. Download: Download high-res image (155KB) Download: Download full-size image