Scaling up anion exchange membrane urea electrolysis towards onboard exhaust gas denitrification: Performance, stability, and regeneration strategies

Electrochemical hydrogen production from commercial Diesel Exhaust Fluid (DEF, 32.5 wt% urea) supplemented with KOH was investigated as a route for onboard hydrogen generation to support low-temperature NO x reduction in automotive aftertreatment systems. A single-cell anion exchange membrane urea electrolyser (AEMUE) was operated under conditions representative of intermittent vehicle operation to evaluate performance, degradation, and recovery. Ampere-level operation was achieved using commercial DEF with 3 M KOH and a Fumatech® membrane. Re-examination of intermittent operating protocols showed that idle periods with continuous electrolyte flow caused greater degradation than galvanostatic operation during accelerated stress testing. Performance losses were associated with irreversible increases in ohmic and kinetic resistances. Periodic cathode-side deionised water flushing restored up to 50 % of the performance loss. Fourier-transform infrared spectroscopy revealed persistent nitrogen-containing species within the membrane, identified as a key cause of incomplete recovery and long-term degradation. These findings provide guidance for improving AEMUE operation and durability.