Study on IrOx-coated gradient-distributed IrOx/Ir with low crystallinity for acidic oxygen evolution reaction

Proton exchange membrane (PEM) water electrolysis has broad application prospects for clean hydrogen production owing to its high efficiency, compact structure, rapid response, and flexible load regulation. However, the sluggish kinetics of the oxygen evolution reaction (OER) under strongly acidic conditions still poses a major challenge to the development of efficient and stable acidic OER electrocatalysts. In this work, a low-crystallinity IrO x /Ir catalyst with a gradient-distributed IrO x coating was successfully prepared by a hydrothermal method. In acidic OER tests, the catalyst exhibited excellent electrocatalytic performance, delivering a mass activity 218 times higher than that of commercial IrO 2 at 1.55 V vs. RHE, and requiring an overpotential of only 231 mV to reach 10 mA·cm −2 . The incorporation of non-crystalline metallic Ir 0 significantly improves the electrical conductivity and intrinsic catalytic activity of the catalyst. Meanwhile, the outer layer of more crystalline iridium oxide effectively protects the highly active low-crystallinity iridium oxide in the interior from dissolution and corrosion, so that the catalyst shows no obvious activity decay after 300 h of continuous operation, indicating good stability.