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

Abstract

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 (OH), superoxide radicals (O2−), and sulfuric acid root radicals (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.