Strong Coupling of Iridium and Boron–Carbon-Nitride Support for Enhanced Acidic Water Oxidation

Supporting iridium (Ir)-based materials on stable and suitable substrates is an efficient strategy to improve their catalytic performance for the oxygen evolution reaction (OER) in harsh acidic environments. Herein, we report a series of Ir catalysts supported on boron-carbon-nitride (BCN), denoted as Ir/BCN. Detailed experiments combined with density functional theory calculations demonstrate strong interactions between Ir nanoparticles (NPs) and the BCN support, significantly contributing to the improved OER performance. Among the synthesized catalysts, the Ir/BCN-75 catalyst outperforms commercial Ir black and IrO₂ in both half-cell and proton exchange membrane water electrolysis (PEMWE) tests. Specially, the Ir/BCN-75 catalyst achieves a high current density of 2.94 A cm⁻² at 1.9 V with a low Ir loading of 0.26 mg cm⁻² in PEMWE measurements, exceeding most Ir-based catalysts reported to date. The BCN support interacts strongly with Ir, wherein Ir-N bonding directs the Ir NP growth and enhances electrocatalytic activity, while Ir-B bonding contributes to the stability of the Ir/BCN catalyst.