Laser Irradiated Noble Metal‐Free High Entropy Oxide 2‐D Sheets for Highly Efficient Anion Exchange Membrane Water Electrolyzers

Abstract High entropy oxides (HEOs) have recently emerged as excellent alternative catalysts that can potentially replace noble metal catalysts such as RuO 2 and IrO 2 for water splitting applications. However, existing methods of synthesizing these catalysts are often tedious. In this work, a straightforward method is proposed using ultra‐fast laser irradiation to synthesize heavily wrinkled noble metal‐free (CoCuFeMnNi) 3 O 4 HEO 2‐D sheets on nickel foam for excellent oxygen evolution reaction (OER) performance. These sheets facilitate the OER at a low overpotential of only 245 mV to achieve 10 mA cm −2 and is stable after 100 h of testing. This performance outmatches the majority of recently reported noble and noble metal‐free HEA and HEO catalysts. As an anode in anion exchange water electrolyzer (AEMWE), a remarkably high current density of 1.722 A cm −2 is achieved at 2.0 V with negligible catalyst deterioration despite 70 h of testing. This result outranks the majority of other state‐of‐the‐art AEMWE catalysts reported today. This work proves that laser irradiation synthesis enables the synthesis of efficient HEO catalysts, and is a pioneer synthesis of HEO 2‐D interconnected sheets using laser irradiation. Crucially, this work proves that noble‐metal free HEOs are highly efficient and durable catalysts in industrial AEMWE devices.