Three-dimensional hierarchically porous PbO2 electrode for electrochemical degradation of m-cresol

Abstract

The modification of PbO2 electrode with high catalytic activity and stability for electrochemical degradation of pollutants remains a great challenge. Accordingly, a novel three-dimensional hierarchically porous PbO2 electrode with polypyrrole (PPy) as middle layer (marked as Ti/SnO2–Sb/PPy/PbO2) was developed for the first time. The physicochemical characterization results showed more intact and ordered “pyramid” structures were formed when the PPy was introduced to be the middle layer of PbO2 electrode. Additionally, the crystallinity of PbO2 and the proportion of adsorbed hydroxyl oxygen were all increased significantly. The electrochemical characterization results showed the active surface area and oxygen evolution overpotential of PbO2 electrode were also improved with PPy middle layer as middle layer. Besides, the electrode film resistance was reduced greatly. Also the PbO2 electrode with PPy middle layer possessed higher degradation ability of m-cresol and lower energy consumption. Above results indicated the physicochemical and electrochemical characterization of PbO2 electrode were all enhanced significantly with the introduction of PPy middle layer. Also the phenomenon that current-controlled reaction would transformed into diffusion-controlled reaction in the process of electrochemical degradation was observed. The effects of experimental parameters on electrochemical degradation were evaluated, indicating lower initial m-cresol concentration, higher current density, temperature and pH were beneficial for electrochemical degradation of m-cresol. Additionally, a possible degradation pathway of m-cresol was proposed. Finally, the continuous experiments of m-cresol degradation indicated the Ti/SnO2–Sb/PPy/PbO2 electrode possessed stable degradation ability and high safety within 30 days.