Benson Eric E, Ha Mai-Anh, Gregg Brian A, van de Lagemaat Jao, Neale Nathan R, Svedruzic Drazenka
National Renewable Energy Laboratory, Golden, CO, 80401, USA.
Sci Rep. 2019 Nov 4;9(1):15906. 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 films. We demonstrate through operando electrochemical experiments that the low HER activity of TiO can reversibly approach those of the state-of-the-art non-precious metal catalysts when the TiO is under tensile strain. At 3% tensile strain, the HER overpotential required to generate a current density of 1 mA/cm 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. 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 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.
我们报告了通过对高度n型掺杂的金红石TiO薄膜施加机械应力来调节析氢反应（HER）和析氧反应（OER）催化活性的能力。我们通过原位电化学实验证明，当TiO处于拉伸应变时，其较低的HER活性可以可逆地接近最先进的非贵金属催化剂的活性。在3%的拉伸应变下，产生1 mA/cm电流密度所需的HER过电位阳极移动260 mV，起始电位为125 mV，这表明动力学过电位大幅降低。当对TiO施加拉伸应变时，在OER过电位中观察到类似但较小的阴极移动。结果表明，HER和OER活性随拉伸应变的显著提高是由于表面活性位点浓度的增加以及反应路径上动力学和热力学势垒的降低。我们的结果突出表明，通过精确控制和逐步增加（即动态）拉伸应力施加于TiO的应变是一种相对于其静态条件下的活性动态调节HER和OER电催化剂电催化性能的有效工具。
