Regulating the Electronic Structure of IrO x /SnO y with NaCl for Efficient Proton Exchange Membrane Water Electrolysis

Abstract

Hydrogen has been considered as a promising energy carrier because of its high gravimetric energy density. However, most hydrogen has been produced by steam methane reforming, which releases significant amounts of CO2 during the process. In contrast, water electrolysis (WE) offers the most sustainable way to produce hydrogen without carbon emissions. Especially, proton exchange membrane water electrolysis (PEMWE) technique has attracted much attention due to its high efficiency, compact design, and fast response to load fluctuations, enabling the integration of renewable energy. However, the inevitable use of precious metal (Ir, Ru) catalyst due to the sluggish kinetics of oxygen evolution reaction (OER) has hindered the practical implementation of PEMWE. In this regard, developing low-content Ir-based catalysts with high activity is critical for enhancing the cost efficiency of PEMWE. This presentation will propose a synthesis strategy for tin oxide-supported iridium oxide (IrO x /SnO y _NaCl) catalyst prepared using NaCl as a sacrificial template. This approach allows uniform dispersion of Ir particles and regulation of its valence states to favor the OER. The synthesized IrO x /SnO y _NaCl catalyst exhibited high OER activity and mass activity comparable to the state-of-the-art Ir-based OER catalysts. Electrochemical and X-ray spectroscopic analyses demonstrated that the use of NaCl template can improve the catalytic activity of IrO x by tuning the valence state ratio (Ir3+/Ir4+). Moreover, IrO x /SnO y _NaCl catalyst showed a high single-cell performance of PEMWE, achieving mass activity 2.6 times higher than commercial IrO2.