BaOx(0.5 MLE 10 MLE)/Pt(111) (MLE: monolayer equivalent) surfaces were synthesized as model NOx storage reduction (NSR) catalysts. Chemical structure, surface morphology, and the nature of the adsorbed species on BaOx/Pt(111) surfaces were studied via X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption (TPD), and low-energy electron diffraction (LEED). For θBaOx < 1 MLE, (...