Preparation of a PbO2 Electrode with Graphene Interlayer and for Electrochemical Oxidation of Doxycycline
Xu Cong, Jiqing Bao
Abstract
A graphene interlayer was introduced into a Ti/SnO 2 -Sb 2 O 3 /PbO 2 electrode by electrophoretic deposition and electro position methods to form a Ti/SnO 2 -Sb 2 O 3 /graphene/PbO 2 electrode (G/PbO 2 ). In comparison to the Ti/SnO 2 -Sb 2 O 3 /PbO2 electrode (PbO 2 ), the surface of the G/PbO 2 electrode was flat with fewer surface cracks, and smaller crystal sizes. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results showed that the G/PbO 2 electrode had a large electrochemically active surface area and more active sites. The accelerated lifetime of the G/PbO 2 electrode was 72 h, which was longer than that of the PbO 2 electrode (40 h). In addition, the graphene interlayer improved the ability to generate OH. The real electrochemical oxidation abilities of the G/PbO 2 and PbO 2 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/PbO 2 electrode were 98.5%, 32.3% and 1.80%, respectively, which was higher than those of the PbO 2 electrode (93.6%, 28.7% and 1.60%, respectively). Furthermore, six intermediate products were identified based on HPLC-MS, and oxidation pathways were proposed.