Effects of Oxygen Defects in Zr Oxide-Based Thin Films on Oxygen Reduction Reaction in Acidic Media

Zirconium oxide thin films were prepared by RF magnetron sputtering as model catalysts for oxygen reduction reaction (ORR) in acidic media. The effects of sputtering conditions on ORR activity in acidic media was investigated. The effect of the deposition temperature on the ORR activity depended on whether the deposition atmosphere contained oxygen (Ar+O 2 , Ar+N 2 +O 2 ) or only nitrogen (Ar+N 2 ). In the range of 300-800 °C of the deposition temperature, the electrodes prepared in an Ar+N 2 showed higher ORR activity. XRD and XPS results showed that the tetragonal phase grew in an Ar+N 2 atmosphere, while a mixed phase of tetragonal and monoclinic phases grew in an Ar+O 2 atmosphere. It was found that Zr oxide thin film with a high proportion of tetragonal phase showed high ORR activity.