Understanding the Role of Corrosion and Reactive Oxygen Species in Electrochemical Ozone Production on Nickel and Antimony Doped Tin Oxide

Electrochemical ozone production (EOP), a six-electron reaction, offers promising green applications for water disinfection and organic synthesis. Nickel and antimony-doped tin oxide (Ni/Sb-SnO2, NATO) electrodes are known to be active for EOP. Still, the mechanism of NATO's selectivity and activity and the origin of its instability need to be clarified. We combine electrochemistry, spectroscopic detection of reactive oxygen species (ROS) using selective chemical probes, oxygen anion chemical ionization mass spectrometry (CIMS), and density-functional theory (DFT) simulations to identify the reaction mechanism and investigate the role of corrosion and homogenous reactive oxygen species in EOP on NATO electrodes. We identify hydrogen peroxide as a critical reaction intermediate. Our results suggest that the presence of nickel in NATO enables the catalysis of hydrogen peroxide to hydroperoxyl radicals, which subsequently undergo oxidation to produce ozone. The isotopic makeup of products shows that water is the primary source of ozone, but it also contains oxygen from the metal oxide lattice. The change in the isotopic generation pattern of ozone suggests that NATO catalysts corrode irreversibly, and the lattice oxygen is not regenerated, explaining NATO's instability.