Modulating the Electrocatalytic Activity of Intermetallic Compounds for the Hydrogen Evolution Reaction via Elastic Strain Engineering

Intermetallic alloys present a promising and cost-effective alternative to Pt-group metals for the hydrogen evolution reaction (HER), addressing the challenges of high cost and limited availability. In this study, the effect of elastic strains on intermetallic thin films of Ag3In, Ni3Fe, and Ni3Sn is investigated to optimize their catalytic activity for the HER. Tensile and compressive strains were introduced into the thin films deposited via magnetron sputtering onto nitinol substrates using the one-way shape memory effect of nitinol. Synchrotron high-resolution X-ray diffraction measurements confirm the introduction of uniaxial elastic strains, with maximum values of up to −1.6% in compression and 1.26% in tension. Electrochemical analyses provided quantitative values of the effect of elastic strain on the catalytic activity. Either tensile (Ag3In) or compressive (Ni3Fe, Ni3Sn) strains enhanced the HER performance by reducing the overpotential at 50 mA/cm2, the Tafel slope, and the charge resistance transfer. The relevance of these results was corroborated by comparing them with the catalytic properties of Pt thin film. Finally, the experimental results were rationalized by means of the theoretical predictions of the adsorption energy of hydrogen, based on density functional theory calculations in combination with microkinetic models. This work highlights the potential of elastic strain engineering to improve the catalytic performance of intermetallic thin films, providing valuable insights into their application as efficient catalysts for hydrogen production.