Ozone is a powerful disinfectant in water treatment, and electrochemical ozone production (EOP) is desirable because it can be safer than current production methods. The greatest challenge for electrochemical ozone production is the lack of catalysts with high selectivity for ozone evolution. Nickel-and antimony-doped tin oxide electrodes synthesized from sol-gels and nanoparticles have been reported to reach ozone current efficiencies up to 50% for electrochemical ozone production. In this study, we present a novel electrodeposition synthesis method that results in current efficiencies up to 63%. The optimal temperature of the post-deposition oxidation treatment is determined by the tradeoff between catalyst stability and crystallinity. Analysis via microscopy and X-ray diffraction suggests that electrodeposited films provide sufficient Ni concentration, surface area, and morphology to support a solution-mediated ozone production reaction.

Direct electrochemical production of dissolved ozone could potentially provide economic wastewater treatment and sanitation or a valuable chemical oxidant. Although Ni‐Sb‐SnO2 electrocatalysts have the highest known faradaic efficiencies for electrochemical ozone production, the activity and selectivity are not yet sufficient for commercial implementation. This work finds that co‐doping Ni and Gd increases the ozone selectivity by a factor of three over Ni alone. These findings are the first demonstration of an active dopant other than Ni in SnO2. Electrochemical and physical characterization show that trends in ozone activity are caused by chemical catalysis, not morphology effects, and that conduction band alignment is not a catalytic descriptor for the system. Selective radical quenching experiments and quantum chemistry calculations of thermodynamic energies suggest that the kinetic barriers to form solution‐phase intermediates are important for understanding the role of dopants in electrochemical ozone production.