Fabrication and enhanced electrocatalytic activity of 3D highly ordered macroporous PbO sub(2) electrode for recalcitrant pollutant incineration

By virtue of the self-assembled colloidal crystal template with face-centered cubic structure, a novel three-dimensional highly ordered macroporous PbO sub(2) (3DOM-PbO sub(2)) electrode was fabricated by electrochemical deposition method. In the 3DOM-PbO sub(2) film, every spherical cavity was interconnected to three adjacent spherical cavities on the upper and lower layer, respectively, and the pore size was about 500 nm. Compared to the traditional flat microcrystalline PbO sub(2) (Flat-PbO sub(2)), the nanocrystalline 3DPO-PbO sub(2) with beta -PbO sub(2) crystal phase possessed larger specific surface area (46 m super(2) g super(-1)), higher oxygen evolution potential (1.92 V), smaller electron transfer resistance (35.5 Omega ), and more abundant crystal defect sites, resulting in better electrocatalytic performance. The electrochemical mineralization of refractory metalaxyl with 3DOM-PbO sub(2) anode demonstrated that, the electrocatalytic reaction followed pseudo-first-order kinetics and the value of apparent rate constant (k sub(app)) is 0.017 min super(-1), about 2.4 times that with Flat-PbO sub(2), and total organic carbon (TOC) and chemical oxygen demand (COD) removals are all approximately 95% after 300 min. The mineralization current efficiency with the 3DOM-PbO sub(2) was much higher than that with the Flat-PbO sub(2), and corresponding electrical energy consumption was lower. Moreover, the intermediates were identified by high-performance liquid chromatography (HPLC) and Gas chromatography-Mass spectrometer (GC-MS), and possible electrocatalytic oxidation mechanism of metalaxyl on the 3DOM-PbO sub(2) electrode was also discussed in detail.