Highly active and CO₂ tolerant Ir nanocatalysts for H₂/CO₂ separation in electrochemical hydrogen pumps

Carbon-supported Pt nanoparticles have been widely used as electrocatalysts for electrochemical hydrogen pumps. However, Pt surfaces are susceptible to poisoning under CO₂ atmosphere, and as a result, need greater applied cell voltages. Instead of Pt as an anode catalyst in electrochemical hydrogen pumps, we synthesized Ir-based catalysts and characterized them by XRD, XPS, TEM, and TGA. The electrochemical characteristics of the Ir catalysts were evaluated by a halfcell test, and their catalytic activities toward the hydrogen oxidation and hydrogen evolution reactions were evaluated by micro polarization analysis. The exchange current density of the Ir catalyst that was heat treated at 300°C was larger than that of commercial Pt. CO₂ stripping analysis confirmed that the Ir catalyst was not affected by CO₂, unlike the Pt catalyst. Focusing on H₂ separation from H₂/CO₂ gas, an evaluation using a single-cell test indicated that the Ir catalyst performed better than the Pt catalyst.