Real-time elemental tracking in liquid electrochemistry using operando ion beam analysis

Ion beam analysis (IBA) techniques are widely used for quantifying the thin film thickness and composition. As they operate under vacuum conditions, their integration with operando electrochemical studies is scarce, primarily due to the complexity of designing compatible electrochemical reactors. We present the design of a novel electrochemical cell tailored to operando IBA of electrochemical materials. To validate its performance, we selected Ni, Ru and Ir electrocatalysts as case studies for the oxygen evolution reaction (OER) in alkaline and acidic conditions. Simultaneous IBA and cyclic voltammetry (CV) measurements were conducted to gain insights into dissolution behaviour of working and counter electrode materials under flow and batch operation mode. Our findings are highly promising since we obtained Ru dissolution rates (8-16 ng cm-2 s-1) that closely match literature values derived from ICP-MS analysis, confirming the quantitative reliability of our operando approach. Moreover, we show that Pt dissolution from the counter electrode in batch operation leads to near-surface Pt enrichment and altered interfacial conditions, highlighting the critical role of electrolyte management in minimizing cross-contamination and ensuring reliable electrochemical measurements. This work paves the way for broader implementation of operando IBA in electrochemical research, enabling real-time quantification of material degradation under realistic operating conditions.