Elastic strain effects on catalysis of a PdCuSi metallic glass thin film.

The influence of strain on catalytic activity has previously been examined directly by calculations and indirectly by experiments. The origin of the phenomenon has been attributed to strain-induced changes in the catalyst electronic structure. By employing a Pd-based metallic glass film capable of large elastic strains, we provide direct experimental evidence for catalytic activity being differently influenced by mechanically applied uniaxial tensile and compressive strains. We demonstrate the effect on the oxygen reduction reaction with cyclic voltammetry (CV) curves at different strain levels and compare X-ray photoelectron spectrometry (XPS) results for unstrained and strained (in uniaxial tension) specimens to confirm valence electron band shifts. The experimental findings are complemented by electronic structure calculations on single crystal Pd, as well as alloys with Cu and Si. The CV and XPS shifts observed in the experiments are consistent in both direction and magnitude to those predicted by theory for single crystal Pd.