From Deposition Stress to Surface Reactivity: Strain-Dependent Hydrogen Evolution on Sputtered Platinum Thin Films

TL;DR

This study investigates how residual strain in sputtered platinum thin films influences their surface reactivity for hydrogen evolution, combining experimental and computational approaches.

Contribution

It reveals the complex interplay between strain, microstructure, and catalytic activity, providing mechanistic insights into strain-dependent HER performance in sputtered Pt films.

Findings

Low sputter pressure yields higher HER activity.

Increased sputter pressure causes microstructural porosity and reduced activity.

DFT shows strain affects hydrogen adsorption energetics.

Abstract

Strain has emerged as a promising approach for tuning electrocatalytic properties, yet its role in sputter-deposited thin films remains poorly understood. In this work, magnetron-sputtered platinum (Pt) thin films with different stress states were prepared by varying the sputter pressure. The resulting changes in microstructure, residual strain, and hydrogen evolution reaction (HER) activity were investigated using complementary characterization techniques and density functional theory (DFT) calculations. Structural analysis reveals a transition of (111)-textured Pt thin films from dense and smooth films at low pressures, to more porous microstructures with increased roughness at higher pressures. Electrochemical measurements show that films deposited at low sputter pressure exhibit the highest HER activity, while higher sputter pressures lead to reduced activity despite increased surface area. DFT calculations demonstrate that lattice strain alters hydrogen adsorption energetics and surface coverage on Pt(111), providing a mechanistic explanation for the observed activity trends. Overall, the results highlight that HER activity in sputtered Pt thin films is governed by the interplay of residual strain, microstructure, and hydrogen coverage.