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

High entropy oxides (HEOs) have recently emerged as excellent alternative catalysts that can potentially replace noble metal catalysts such as RuO₂ and IrO₂ 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)₃O₄ 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.