Cerium doping modulates the surface electronic structure of IrOx/TiN to promote the stability of acid oxygen evolution

Abstract

The stability of supported Ir-based catalysts in acid oxygen evolution reaction (OER) remains a pressing challenge, which hinders the commercial viability of proton exchange membrane water electrolysis (PEMWE) technology. Herein, we propose a cerium doping strategy to enhance the stability of supported Ir-based catalyst toward OER. The Ce-doped supported catalysts, designated as Ce-IrOx/TiN, were synthesized using an organic colloidal method. Transmission Electron Microscopy (TEM) analysis reveals highly dispersed IrOx nanoparticles averaging 1.5 nm on the TiN support. X-ray Photoelectron Spectroscopy (XPS) investigations further elucidate that Ce doping effectively stabilizes the Ir species predominantly in states below 4+, crucial for modulating the surface electronic structure and thereby improving both the activity and stability of the catalysts. Electrochemical characterization highlights the superior performance of the optimized catalyst, 6 %-Ce-IrOx/TiN, with an impressively low overpotential of 242 mV at 10 mA cm−2 and a Tafel slope of 57.5 mV dec−1, showcasing its significance in facilitating OER. Moreover, its mass activity surpasses that of commercial IrO2 by 5.1 times at 1.7 V. Prolonged constant current testing further demonstrates the exceptional stability of the catalyst, affirming the critical role of Ce doping as a pivotal strategy for enhancing the stability of supported Ir-based catalysts and advancing the prospects for robust OER performance in PEMWE systems.