  Understanding the role of elastic strain in modifying catalytic reaction
rates is crucial for catalyst design, but experimentally, this effect is often
coupled with a ligand effect. To isolate the strain effect, we have
investigated the influence of externally applied elastic strain on the
catalytic activity of metal films towards the hydrogen evolution reaction
(HER). We show that elastic strain tunes the catalytic activity in a controlled
and predictable way. Both theory and experiment show strain controls reactivity
in a controlled manner consistent with the qualitative predictions of the HER
volcano plot and the d-band theory: Ni and Pt activity were accelerated by
compression, while Cu activity was accelerated by tension. By isolating the
elastic strain effect from the ligand effect, this study provides a greater
insight into the role of elastic strain in controlling electrocatalytic
activity.
