Lotus root-like RuIr alloys with close-packed (0001) branches: Strain-driven performance for acidic water oxidation

Abstract

Achieving composition tunability and structure editability of nanoalloys with high level strain may be an efficient strategy to remarkably boost catalytic performance toward oxygen evolution reaction (OER) in acidic water oxidation. Herein, lotus root-like RuIr alloys with native micro-strain were constructed by an epitaxial growth of Ru-richened hcp-(0001) branches on Ir-richened fcc-(111) seeds using a polyol thermal synthesis strategy. The resultant Ru60Ir40 alloy shows an OER overpotential of 197 mV at 10 mA cm−2 and a Tafel slope of 46.59 mV dec−1, showing no obvious activity decay for 80 h continuous chronopotentiometry test in 0.5 M H2SO4. The related characterizations including X-ray absorption fine structure (XAFS) spectroscopy and density functional theory (DFT) calculations show that that the remarkably improved activity of the lotus root-like alloy can be attributed to the (0001) facet-triggered strain, which can efficiently optimize the electronic band structure of the active metal and the weakening of the chemisorption of oxygen-containing substances to boost OER electrocatalysis. Therefore, this work provides a new strategy to designing a class of advanced electrocatalysts with high strain using diverse nanostructures as building materials for carbon-free clean energy conversion systems.