Preparation of Solid Solution and Layered IrO<i><sub>x</sub></i>–Ni(OH)<sub>2</sub> Oxygen Evolution Catalysts: Toward Optimizing Iridium Efficiency for OER
Jonathan Ruiz Esquius, Gerardo Algara‐Siller, Ioannis Spanos, Simon J. Freakley, Robert Schlögl, Graham J. Hutchings
Abstract
Minimizing iridium loading in oxygen evolution reaction (OER) catalysts, without impairing electrocatalytic activity and stability is crucial to reduce the cost of water electrolysis. In this work, two Ir0.5Ni0.5Ox mixed oxide catalysts with layered and solid solution morphologies were prepared by modifying a facile hydrothermal methodology. The catalytic OER activity and stability of the Ir–Ni catalyst with a homogeneous distribution (IrNi-HD) was seriously compromised compared to pure IrOx due to the high concentration of surface nickel prone to corrosion under reaction conditions. However, the design of layered IrOx–Ni(OH)x (IrNi-LY) with Ir at the exposed surface allowed a 50% reduction in the molar concentration of the precious metal on the electrode compared to IrOx without impairing the catalytic activity or stability. As a result, IrNi-LY outperformed IrOx in activity when normalized to the Ir mass.