Exploratory Evaluation of Er/Y-Modified RuO2 for Acidic Oxygen Evolution

Abstract The intrinsic instability of ruthenium dioxide (RuO2) under acidic oxygen evolution reaction (OER) conditions remains a critical challenge for the development of durable OER electrocatalysts. Here, we present an exploratory comparative half-cell investigation of one nominal Er/Y-modified RuO2 composition. Under the specified conditions (0.1 M HClO4, room temperature, three-electrode configuration), Er0.1Y0.1Ru0.8O2 required 226 mV to reach 10 mA cm–2, compared with 257 mV for identically prepared h-RuO2. During an 80,000 s chronopotentiometry test, the modified sample showed lower Ru leaching than h-RuO2 (117 versus 281 μg L–1). Fresh-state XRD, HRTEM, XPS, EIS, and DFT-PDOS identify structural and electronic differences that are consistent with a qualitative working model of Er/Y modification. The current data do not establish individual Er/Y contributions, an Er/Y-ratio-performance relationship, an OER pathway, or PEMWE/MEA performance. Systematic composition-controlled, operando, and device-level measurements are required to test these questions.