Ion Beam Analysis of MoNi₄-MoO₂ Catalyst Layer for Anion Exchange Membrane Electrolyzer

There has been an increased interest in Anion Exchange Membrane (AEM) electrolyzer technology enabling zero-gap configuration lately. This technology also allows non-noble metal-based materials to be used as catalyst layers in an alkaline environment. In this research, MoNi₄ supported by MoO₂ nanorods has proven to be a promising electrocatalyst for Hydrogen evolution reaction (HER) with a decreased overpotential of 40 mV at 10 mA/cm² with increased current density, and stability for almost 12 hours in half-cell configuration. However, it is important that the material be used as a catalyst layer in membrane electrode assembly to have the capacity to tolerate high steady-state potentials for extended periods of time in real operating systems. The aim of this study is to analyze the AEM electrode assembly with MoNi₄-MoO₂ as the cathode layer synthesized via hydrothermal synthesis for overall metal loading corresponding to the improved efficiency and catalyst dissolution arising due to the interaction between the catalyst layer and the ionomer membrane. The cathode catalyst synthesized was characterized by X-Ray diffraction, SEM and X-Ray photoelectron spectroscopy for structural, morphological and surface composition. Further, nuclear techniques like Rutherford Backscattering Spectroscopy (RBS) employed to provide information regarding the thickness and stoichiometry of the catalyst layer and metal dissolution in the ionomer membrane, and Nuclear Reaction Analysis (NRA) was utilized to study different defects in the ionomer membrane by high-resolution Hydrogen depth profiling after the operation. Overall, this work presents a better understanding of catalyst degradation effects on the ionomer membrane and vice versa responsible for the voltage and mass transport losses in AEM electrolyzers.