Phase/Size-Controlled Synthesis of Nanostructured PbO2 Microspheres for Efficient Electrochemical Ozone Generation

Graphical O 3 generation : By adjusting the concentration of sodium hydroxide during hydrothermal preparation process, the phase and size-controlled synthesis of PbO 2 was achieved. Later, a phase/size effect in electrochemical ozone generation reaction was found and an optimal PbO 2 microsphere catalyst was successfully screened out. This achieved a 61 % higher O 3 current efficiency at 2 A cm −2 than electrochemically prepared PbO 2 -based catalyst. Traditional electrochemically prepared lead dioxide (e-PbO 2 ) is one of the most used electrode materials for electrochemical ozone production (EOP), because of its high catalytic activity, excellent electrical conductivity, relative stability and low cost. But the electrochemically prepared conditions are complicated and harsh. Bulk PbO 2 electrodes have the very limited surface area and are inconvenient to process into the fine film electrodes for a PEM electrolyser. In contrast, chemical synthesis is easy to prepare uniform PbO 2 catalysts with high surface area and catalytic activity. Here, a facile one-pot approach to prepare a highly active PbO 2 microsphere catalyst was established and used for the EOP reaction in a PEM ozone generator. Sodium hydroxide could be used to regulate the relative content of α/β allotropic phase and crystallite size of PbO 2 microspheres. Experiment results revealed that high β phase content and large β-PbO 2 crystallite size were beneficial to the high EOP activity. By optimizing the composition and crystal structure, chemically prepared PbO 2 could have much better EOP performance than e-PbO 2 .