Effects of PbO2/Pb3O4 ratio alteration for enhanced electrochemical advanced oxidation performance

Abstract

PbO2, PbO2/Pb3O4 composite, and Pb3O4 were synthesized respectively via the simple hydrothermal method under different reaction durations (3–48 ​h). All the prepared samples were used as anode materials to decontaminate methyl orange (MO) to explore the corresponding electrochemical advanced oxidation performance. The detailed experimental designs suggested that the combination of PbO2 and Pb3O4 offered enhanced electrochemical advanced oxidation performance, which was due to possible synergistic effects. XPS results suggest that the content of adsorbed oxygen species (Oads) is obviously higher in PbO2/Pb3O4 composite. It is very likely due to more oxygen vacancies in the crystal structure of PbO2/Pb3O4 composite, which will adsorb more oxygen species, promote charge transfer and provide more electrochemical active surface area to generate oxidizing agents. Besides, the presence of Pb3O4 can suppress the oxygen evolution and improve the accelerated life. Meanwhile, the effects of current density, catalyst loading amount and initial MO concentration on electro-catalysis degradation of MO were explored. Experimental results suggested that MO removal efficiency was 94.3%, the reaction kinetic constant could reach 2.08 ⅹ 10-2 min-1, and COD removal efficiency was 34.2% after 150 ​min of reaction under optimized conditions: current density was 5 ​mA ​cm-2, catalyst loading amount was 1 ​mg ​cm-2 and initial MO concentration was 50 ​mg ​L-1. Furthermore, possible degradation mechanisms of MO was proposed according to the analyzed results obtained from UV–Vis and HPLC-MS.