Electrolyte-dependent nitrogen bubble dynamics in hydrazine oxidation at Pt ultramicroelectrodes

The hydrazine oxidation reaction (HzOR) was investigated by cyclic voltammetry in electrolytes containing different ionic species to characterize gas-evolution potentials and interfacial kinetics. Systematic variations in current response and onset potential were observed with changes in electrolyte composition and concentration. These trends allowed estimation of the critical surface concentration required for bubble nucleation, providing quantitative insight into gas behavior at electrified interfaces. Measurements with Pt ultramicroelectrodes revealed a distinct current drop arising from N 2 bubble formation, serving as an electrochemical signature of interfacial gas nucleation. In the presence of iodide, an additional anodic peak was detected, demonstrating direct I − involvement in the interfacial reaction pathway and identifying a secondary oxidation process beyond the canonical HzOR. These results establish a framework for assessing electrolyte-dependent bubble dynamics and their influence on gas-evolving electrochemical reactions. • Electrolyte-specific effects govern hydrazine oxidation at Pt ultramicroelectrodes. • Nitrogen bubble nucleation potentials shift with cation, anion, and halide identity. • Iodide induces a unique secondary oxidation peak during hydrazine oxidation. • Findings provide mechanistic insight into bubble-mediated current suppression.