Hydrophobic Ce-doped β-PbO₂-SDS anode achieving synergistic effects for enhanced electrocatalytic oxidation of As(III)

To strengthen the utilization of free radicals and effectively enhance electrocatalytic performance and service lifetime of the β-PbO₂ electrode, herein, a novel hydrophobic TNAs/SnO₂/PPy/β-PbO₂-Ce-SDS (abbreviated as β-PbO₂-Ce-SDS) anode was synthesized by doping Ce³⁺ and anionic surfactant (SDS) to TNAs/SnO₂/PPy/β-PbO₂ (abbreviated as β-PbO₂), which was constructed by growing SnO₂/PPy/β-PbO₂ multilayers on TiO₂ nanotube arrays (TNAs) via combination of electrodeposition and electro-polymerization processes. Notably, co-modification with Ce³⁺ and SDS remarkably enhanced the surface hydrophobicity, electrochemical performance and catalytic ability of β-PbO₂ anode. Such β-PbO₂-Ce-SDS anode not only substantially enhanced the As(III) conversion (96.96%) in the electrocatalytic oxidation process, but also prominently strengthened its service lifetime. Furthermore, the as-prepared β-PbO₂-Ce-SDS anode possessed an excellent stability as its kinetic constant was only reduced from 0.18 to 0.14 min⁻¹ even underwent 10 cycles of the electrocatalytic process, while that of the unmodified β-PbO₂ electrode decreased markedly by about 49%, owing to its appropriate surface hydrophobicity, smaller grains and denser β-PbO₂ layer. The reaction mechanism of electrocatalytic oxidation was associated with synergistic effects of hydroxyl radical (^[rad]OH), superoxide radicals (^[rad]O₂⁻), and sulfuric acid root radicals (^[rad]SO₄⁻). The β-PbO₂-Ce-SDS anode provides a novel and feasible approach to development of various electrodes by doping metal ions and/or regulating with surfactants.