Unraveling the Role of F in Electrochemical Ozone Generation on the F-Doped PbO2 Electrode

Because of its metal-like conductivity, excellent catalytic activity, and acid resistance, lead dioxide (PbO2) is the most used electrocatalyst for the practical electrochemical ozone production (EOP) technique. Introducing fluorine (F) into PbO2 electrodes or electrolytes can significantly improve EOP activity. However, there is still lack of valid evidence on understanding the role of doping F in the PbO2 electrode. In this work, we report a comprehensive study on the effect of F on EOP activity on electrochemically prepared PbO2 electrodes. F doping suppresses the side reaction of dioxygen (O2) evolution by inhibiting the formation of an α phase impurity of PbO2 electrodes. The more hydrophobic surfaces by doping F promote O2 adsorption as evidenced by low-temperature O2-temperature-programmed desorption experiments and thus are more favorable for ozone (O3) generation. The in situ isotope labeling oxygen (18O2) experiment proves that at room temperature, O2 can adsorb and dissociate on the operando PbO2 electrode surface and participate in the formation of O3 molecules. This work provides a comprehensive understanding of doping F for enhanced EOP.