Mechanistic investigations of the promoting role of Rh on the NSR performance of NOx storage BaO-based catalysts

► Barium nitrates decomposes at lower temperature with Rh present compared to Pt. ► NOx spill-over is increased using Rh compared to Pt, due to increased O2 desorption. ► N2O dissociation forming N2 and O2 occurs already at 373 K on Rh, but 573 K on Pt. ► NOx storage in presence of water is much slower, but the storage capacity is larger. ► Water increases formation of bulk nitrates with higher stability.