Preparation of a PbO2 Electrode with Graphene Interlayer and for Electrochemical Oxidation of Doxycycline

A graphene interlayer was introduced into a Ti/SnO2-Sb2O3/PbO2 electrode by electrophoretic deposition and electro position methods to form a Ti/SnO2-Sb2O3/graphene/PbO2 electrode (G/PbO2). In comparison to the Ti/SnO2-Sb2O3/PbO2 electrode (PbO2), the surface of the G/PbO2 electrode was flat with fewer surface cracks, and smaller crystal sizes. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results showed that the G/PbO2 electrode had a large electrochemically active surface area and more active sites. The accelerated lifetime of the G/PbO2 electrode was 72 h, which was longer than that of the PbO2 electrode (40 h). In addition, the graphene interlayer improved the ability to generate OH center dot. The real electrochemical oxidation abilities of the G/PbO2 and PbO2 electrodes were also studied using doxycycline (DC) as a model pollutant. After 150 min of electrolysis, the DC, total organic carbon (TOC) removal rate and instantaneous current efficiency (ICE) of the G/PbO2 electrode were 98.5%, 32.3% and 1.80%, respectively, which was higher than those of the PbO2 electrode (93.6%, 28.7% and 1.60%, respectively). Furthermore, six intermediate products were identified based on HPLC-MS, and oxidation pathways were proposed.