Formation of Continuous Pt Films on the Graphite Surface by Atomic Layer Deposition with Reactive O₃

Because graphite surfaces are chemically stable, it is difficult to form a uniform layer on graphite by atomic layer deposition (ALD), which is a surface reaction-based deposition method. In this work, reactive O 3 is employed for Pt ALD as a counter reactant, and a continuous Pt film is achieved on the graphite surface. The growth morphology of the O 3 -based Pt ALD process differs significantly from that using an O 2 reactant, in which selective growth occurs on step edges of graphite. Pretreatment of the graphite with O 3 prior to Pt ALD using an O 2 reactant shows a continuous Pt film morphology similar to that obtained from the full O 3 -based ALD process. The analysis indicates that O 3 etches the graphite surface and generates pits containing additional step edges, resulting in an increase in the extent of Pt nucleation. The nucleation of Pt is less active at lower deposition temperatures because the generation of additional step edges is dependent on temperature. This Pt ALD process using a reactive O 3 reactant can be an effective route for fabricating a uniform and continuous Pt catalyst on three-dimensional carbon electrodes for highly efficient fuel cells.