Strategy for enhancing the electrocatalytic performance of Ti/β-PbO2 anode: Optimizing SnO2 intermediate layer by Cs doping and application for the efficient removal of mixed fluoroquinolones

In this paper, the electrocatalytic performance of Ti/β-PbO2 anode was improved by doping Cs into SnO2 intermediate layer (Ti/Cs-SnO2/β-PbO2) for the efficient degradation of fluoroquinolone wastewater. Compared with the conventional Ti/Sb-SnO2/β-PbO2 anode, Cs-SnO2 with the rougher surface increased the deposition amount and the thickness of β-PbO2 active layer, thus forming the denser PbO2 coating with smaller particle size and exposing more active sites. The partial replacement of Sn by Cs with the smaller ion radius induced the deformation of crystal lattice of SnO2, which further led the outer β-PbO2 active layer grew along the advantageous (200) crystal plane and formed more point defects in the crystal lattice of β-PbO2. Thereby, the electron transfer rate at the anode interface was accelerated and the electrocatalytic performance of Ti/β-PbO2 was significantly improved. To verify the practical application of the improved Ti/Cs-SnO2/β-PbO2 electrode, levofloxacin (LFX) and ciprofloxacin (CIP) were selected as the typical target fluoroquinolones to evaluate the degradation efficiency of Ti/Cs-SnO2/β-PbO2 anode. The removal rate exceeded more than 90% for the single and mixed fluoroquinolones wastewater. Moreover, after 5 times’ recycle, the degradation efficiency of LFX on Ti/Cs-SnO2/β-PbO2 anode still remained over 90%. The potential mechanism of the enhanced electrocatalytic performance of Ti/Cs-SnO2/β-PbO2 and the degradation pathways of fluoroquinolones were also inferred. It’s the first time to enhance the electrocatalytic performance of the Ti/β-PbO2 anode by introducing monovalent alkali metal (CS) into the SnO2 intermediate layer and the proposed Ti/Cs-SnO2/β-PbO2 anode would be a promising candidate to realize the efficient removal of the practical fluoroquinolones antibiotic wastewater.