Enhanced Activity and Stability of PbO2 Electrodes by Modification with Octadecyl Phosphonic Acid

Abstract

A novel Ti/Sn-SbOx/PbO2-ODP electrode was constructed using a β-PbO2 layer modified with octadecyl phosphonic acid (ODP) through a co-electrodeposition method. Scanning electron microscopy with an energy dispersive spectrometer, X-ray diffraction and contact angle goniometry confirmed that ODP was successfully embedded into the β-PbO2 layer of Ti/Sn-SbOx/PbO2-ODP, increasing the water contact angle at the electrode surface from 75.9° to 133.9°. The Ti/Sn-SbOx/PbO2-ODP electrode exhibited excellent electrocatalytic oxidation of ciprofloxacin (CIP). The pseudo first-order rate constant for CIP removal was 3.92 h−1 at an electrolytic potential of 10 V, 2.6 times greater than that when using the unmodified electrode. Moreover, electrode stability was greatly improved after ODP modification. The Ti/Sn-SbOx/PbO2-ODP electrode had longer accelerated life (324 h) than the Ti/Sn-SbOx/PbO2 electrode (91 h). The enhanced electrocatalytic performance of Ti/Sn-SbOx/PbO2-ODP was attributed to improved utilization of hydroxyl radicals (•OH) resulting from higher oxygen evolution potential. Furthermore, the hydrophobic surface of Ti/Sn-SbOx/PbO2-ODP was beneficial for stronger adsorption of CIP, as evidenced by the initial surface concentration test.