Effect of elastic strains on the electrocatalytic activity of Au thin films for the hydrogen evolution reaction

• A novel strategy based on NiTi shape memory effect is used to introduce elastic strains in Au thin films. • Electrochemical tests prove that tensile strains increase the catalytic activity for HER of Au thin films. • This methodology paves the path towards application of elastic strain engineering for hydrogen production. Platinum-group metals are currently the most efficient catalysts for hydrogen evolution reaction (HER), however their high cost and scarcity urge introduction and development of affordable alternatives. Herein, the effect of elastic strains on gold (Au) thin films is investigated to tune and enhance their catalytic activity towards HER. Tensile and compressive strains are introduced into Au films deposited via magnetron sputtering onto nitinol substrates using one-way shape memory effect of the alloy. The generated elastic strains are measured by X-ray diffraction, revealing maximum ∼ 0.43 % tension and ∼ 0.25 % compression. Electrochemical tests demonstrate that applying tensile strains to the Au thin film increases the HER catalytic activity, e.g., by reducing the overpotential at 50 mA/cm 2 by 24 %. On the contrary, compressive strains decrease the catalytic activity, resulting in an increased overpotential of 32 %. Such effect is further confirmed from the kinetics study through Tafel analysis and charge transfer resistance measurements. Accordingly, this study not only results in Au samples with improved HER activity but also paves the path towards better understanding and application of elastic strain engineering for metals with enhanced catalytic activity for sustainable hydrogen production.