Fabrication of three-dimensional networked PbO2 anode for electrochemical oxidation of organic pollutants in aqueous solution

To improve the electrocatalytic performance of PbO2 anode, the titanium mesh was used as substrate to fabricate a three-dimensional networked PbO2 (3DN-PbO2) anode. The morphology, structure, composition, and electrochemical performance of 3DN-PbO2 anode were evaluated using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, ·OH radicals generation test, cyclic voltammetry, electrochemical impedance spectroscopy, as well as electrochemical oxidation of p-nitrophenol (p-NP). Compared with traditional two-dimensional planar PbO2 (2DP-PbO2) anode, the 3DN-PbO2 anode possessed smaller crystal size, more compact structure, more chemisorption oxygen, stronger ·OH radicals generation ability, more abundant active sites, and smaller electron transfer resistance, resulting in better electrocatalytic performance for degradation of p-NP. The degradation rate constant (kapp) of p-NP on 3DN-PbO2 anode was 0.0489 min–1, more than 2 times that of 2DP-PbO2 anode (0.0229 min–1). In addition, the influence of operating parameters (current density, pH and temperature) on the p-NP degradation and the degradation pathway of p-NP were also investigated. Finally, the stability of electrodes was estimated using 15-cycle electrochemical oxidation test and accelerated lifetime test, and both of 3DN-PbO2 and 2DP-PbO2 electrodes exhibited high reusability for p-NP degradation.