IrOx-MoO3 nano-heterostructure electrocatalysts for efficient acidic water oxidation

Abstract

Rational design of Ir-based electrocatalyst with high performance and low cost remains as an urgent requirement to speed up the sluggish acidic water oxidation to produce hydrogen in renewable energy conversion and storage systems. In this work, the highly dispersed IrOx nanoparticles are fabricated on MoO3 sheets coated Ti meshes (c-IrOx-MoO3/Ti) as efficient electrocatalytic electrodes for acidic water oxidation. The heterogeneous c-IrOx-MoO3/Ti catalysts show much higher acidic oxygen evolution reaction activity (∼200 mV overpotentials at 10 mA cm−2) and long-term stability (longer than 130 h at 100 mA cm−2) with extremely low Ir content (∼28.35 μgIr cm−2) as compared to the IrOx/Ti and commercial IrO2 catalysts. The special intertwined formation of MoO3 sheets through electrodeposition effectively promotes the uniform dispersion of IrOx nanoparticles and the electrocatalytic performance. Theoretical calculations reveal that the electronic modulation on the MoO3-IrOx heterogeneous interface optimized the adsorbed energies for oxygen intermediates on the active Ir sites of the catalysts. The self-assembled proton exchange membrane single-cell electrolyzer test further verifies that the fabricated c-IrOx-MoO3/Ti catalysts demonstrate a greatly lower voltage and higher stability for water electrolysis than the commercial IrO2 catalysts. This work provides a new pathway to designing highly active and acid-resistant Ti-supported water oxidation catalysts with ultra-low Ir content.