H*_ads dynamics engineering via bimetallic Pd–Cu@MXene catalyst for enhanced electrocatalytic hydrodechlorination

Electrocatalytic hydrodechlorination (EHDC) is a promising approach to safely remove halogenated emerging contaminants (HECs) pollutants. However, sluggish production dynamics of adsorbed atomic H (H*_ads) limit the applicability of this green process. In this study, bimetallic Pd–Cu@MXene catalysts were synthesized to achieve highly efficient removal of HECs. The alloy electrode (Pd–Cu@MX/CC) exhibited better EHDC performance in comparison to Pd@MX/CC electrode, resulting in diclofenac degradation efficiency of 93.3 ± 0.1%. The characterization analysis revealed that the Pd⁰/Pd^II ratio decreased by forming bimetallic Pd–Cu alloy. Density functional theory calculations further demonstrated the electronic configuration modulation of the Pd–Cu@MXene catalysts, optimizing binging energies for H* and thereby facilitating H*_ads production and tuning the reduction capability of H*_ads. Noteably, the amounts and reduction potential of H*_ads for Pd–Cu@MXene catalysts were 1.5 times higher and 0.37 eV lower than those observed for the mono Pd electrode. Hence, the introduction of Cu into the Pd catalyst optimized the dynamics of H*_ads production, thereby conferring significant advantages to EHDC reactions. This augmentation was underscored by the successful application of the alloy catalysts supported by MXene in EHDC experiments involving other HECs, which represented a new paradigm for EHDC for efficient recalcitrant pollutant removal by H*_ads.