Strain Regulation to Optimize the Acidic Water Oxidation Performance of Atomic-Layer IrO_x

摘要

Strain regulation has become an important strategy to tune the surface chemistry and optimize the catalytic performance of nanocatalysts. Herein, the construction of atomic-layer IrOx on IrCo nanodendrites with tunable Ir Symbol of the Klingon Empire O bond length by compressive strain effect for oxygen evolution reaction (OER) in acidic environment is demonstrated. Evidenced from in situ extended X-ray absorption fine structure, it is shown that the compressive strain of the IrOx layer on the IrCo nanodendrites decreases gradually from 2.51% to the unstrained state with atomic layer growth (from approximate to 2 to approximate to 9 atomic layers of IrOx), resulting in the variation of the Ir Symbol of the Klingon Empire O bond length from shortened 1.94 angstrom to normal 1.99 angstrom. The approximate to 3 atomic-layer IrOx on IrCo nanodendrites with an Ir Symbol of the Klingon Empire O bond length of 1.96 angstrom (1.51% strain) exhibits the optimal OER activity compared to the higher-strained (2.51%, approximate to 2 atomic-layer IrOx) and unstrained (>6 atomic-layer IrOx) counterparts, with an overpotential of only 247 mV to achieve a current density of 10 mA cm(-2). Density functional theory calculations reveal that the precisely tuned compressive strain effect balances the adsorbate-substrate interaction and facilitates the rate-determining step to form HOO*, thus assuring the best performance of the three atomic-layer IrOx for OER.