High‐Efficiency Iridium‐Yttrium Alloy Catalyst for Acidic Water Electrolysis

Abstract Proton exchange membrane (PEM) water electrolysis holds great promise in revolutionizing clean energy production by enabling the efficient generation of hydrogen. Nevertheless, a formidable challenge persists in the realm of designing electrocatalysts that are both highly active and acid‐resistant during the oxygen evolution reaction (OER), thereby mitigating the substantial kinetic barrier. In this study, the facile synthesis of iridium‐yttrium (IrY) alloy nanocatalysts via a thermal shock method is introduced, which exhibits exceptional activity in the context of acidic water oxidation. Through the strategic incorporation of dispersed Y into the lattice of Ir metal, the IrY catalyst demonstrates a notably low overpotential of 255 mV at a current density of 10 mA cm −2 and showcases remarkable catalytic stability in acidic electrolytes, enduring for over 500 h with a high current density of 100 mA cm −2 . Through a comprehensive set of in situ characterizations and analytical methods, the formation of a surface Ir‐based oxide layer, induced by deprotonation and electrochemical oxidation is unveiled, which is notably stabilized by the presence of Y dopants. This stabilization of the active site imparts enhanced resistance to over‐oxidation and dissolution, underpinning the exceptional stability of the catalyst. Theoretical calculations suggest that the incorporation of Y into the catalyst structure has a significant impact on enhancing the reactivity of the oxygen intermediate (O*) at adjacent Ir sites, thus lowering the overpotential and promoting OER activity. The alloying approach presents a straightforward method for achieving atomic‐level modifications in catalyst design and can pave the way for the development of more effective and economically viable OER catalysts and beyond.