Dynamic Tuning of a Thin Film Electrocatalyst by Tensile Strain

• Published in: Scientific reports 2019-11, Vol.9 (1), p.15906-8, Article 15906
• Main Authors: Benson, Eric E., Ha, Mai-Anh, Gregg, Brian. A., van de Lagemaat, Jao, Neale, Nathan R., Svedruzic, Drazenka
• Format: Article
• Language: English
• Subjects: 639/301; 639/4077; 639/638; Catalysts; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; electrocatalysis; Electrochemistry; Humanities and Social Sciences; MATERIALS SCIENCE; multidisciplinary; Physical growth; Science; Science (multidisciplinary); Strain; tensile strain; Tensile stress; Thin films; Titanium dioxide; water splitting
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-52245-y

We report the ability to tune the catalytic activities for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) by applying mechanical stress on a highly n-type doped rutile TiO 2 films. We demonstrate through operando electrochemical experiments that the low HER activity of TiO 2 can reversibly approach those of the state-of-the-art non-precious metal catalysts when the TiO 2 is under tensile strain. At 3% tensile strain, the HER overpotential required to generate a current density of 1 mA/cm 2 shifts anodically by 260 mV to give an onset potential of 125 mV, representing a drastic reduction in the kinetic overpotential. A similar albeit smaller cathodic shift in the OER overpotential is observed when tensile strain is applied to TiO 2 . Results suggest that significant improvements in HER and OER activities with tensile strain are due to an increase in concentration of surface active sites and a decrease in kinetic and thermodynamics barriers along the reaction pathway(s). Our results highlight that strain applied to TiO 2 by precisely controlled and incrementally increasing (i.e. dynamic ) tensile stress is an effective tool for dynamically tuning the electrocatalytic properties of HER and OER electrocatalysts relative to their activities under static conditions.