Tuning the Electrocatalytic Performance of Cobalt Thin Films via Oxygen Annealing for Oxygen Evolution Reactions in Alkaline Media

Abstract

The deposition of thin films using vacuum techniques is highly desirable for device fabrication due to the high reproducibility, uniformity, smoothness, and desired thickness. In this report, cobalt thin films were fabricated by the thermal evaporation method

the as-prepared samples were annealed at different temperatures (350 °C, 450 °C and 550 °C) in an oxygen atmosphere to form cobalt oxide. The method of metal thin-film annealing not only transforms them into metal oxides but also reduces major defects, having a significant impact on device performance. Various characterizations examined the morphological and structural characteristics of the altered samples. The electronic structure of cobalt thin films was extracted from DFT calculations. The sample annealed at 350 °C showed the lowest Tafel slope of 119 mV/dec. As the annealing temperature is raised while using these samples for oxygen evolution reaction applications in 0.5 M KOH solution, the electrode performance rapidly declines. Therefore, the present study demonstrates that the deposited thin films for electrocatalysis applications are potentially used for energy production. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2026.