Electronic structure modulation on PdCo bimetal for enhanced atomic hydrogen mediated electro-dehalogention of 2,4,6-trichlorophenol.

Atomic hydrogen (H*)-mediated indirect electrochemical reduction has regarded as a highly effective strategy for halogenated organic pollutants (HOPs) removal in wastewater. The efficient generation and prompt utilization of H* are critical factors which directly determine the degradation performance. This study presented a new strategy for the electro-reduction of a typical HOP-2,4,6-trichlorophenol (2,4,6-TCP), achieved by modulating the electronic structure of a PdCo bimetal electrode (PdCo/CP). Through characterizations and density functional theory (DFT) analysis, ZIF-67 as the Co source could effectively improve the uniform distribution of Pd and Co, which exposed more active sites for H* on-demand generation. Meanwhile, the introduction of Co atoms and the optimum of Pd/Co ratios modulated the electronic structure of Pd sites. In 120 min, 92 % 2,4,6-TCP (initial concentration 10 mg/L) was degradated with a reaction rate constant (k) of 0.103 min, which was 2.1 times higher than that of Pd/CP electrode. Lower Gibbs free energy for hydrogen adsorption (-0.477 eV) was found in PdCo/CP which benefited the surface-adsorbed H* stability for enhanced utilization. The degradation pathway of 2,4,6-TCP was further studied. These findings highlight the critical role of modulating the electronic structure of the electrode to optimize the utilization of surface-adsorbed active intermediates, presenting a novel and promising approach for advancing wastewater treatment technologies.