Enhancing Chemical Stability of Pt Ultrathin Films on Substrates by Controlled Intermixing of Pt‐Zn at Interface

Platinum (Pt) ultrathin films supported on substrates can enable reduced metal loading, but their long‐term stability in harsh environments remains a challenge. This work establishes that an optimal thickness of the intermediate adhesion layer can provide this stability. Pt ultrathin films (20 nm) are deposited on Silicon substrates using a Zinc (Zn:4, 6 nm) adhesion layer in a DC magnetron sputtering system. Results show that the addition of the Zn layer nearly doubled the adhesion strength of Pt films, from 420 to 780 μN. A maximum of 4 nm Zn leads to longevity of Pt films in 1 m H₂SO₄ environments with negligible variation in sheet resistance (15–20 Ω sq⁻¹) for over 4 months. Films with 6 nm Zn deteriorated within 2 weeks. Observed adhesion and stability are due to limited (for 4 nm) and complete intermixing (for 6 nm) of Zn and Pt, resulting in the formation of Pt‐Zn solid solution. Solid solution formation is validated by X‐ray photoemission spectroscopy, X‐ray diffraction, and density functional theory. This study opens up the possibility of using engineered adhesion layers to enhance the durability of ultrathin metal films for a wide range of industrial applications.