Tailoring Ba geometry on NiBaY ternary metal oxides to boost NO decomposition in the presence of oxygen

NO decomposition via high-temperature catalysis is a well-established and promising approach for NO x abatement, yet its efficacy is compromised by the inhibitory effect of oxygen present in fuel combustion. By adjusting the compositional ratios of Ni, Ba, and Y as well as the calcination temperature, various Ba-containing structural geometries can be created on Y 2 O 3 , namely BaNiO 3 , Ni-BaO, and highly dispersed NiBa. Compared to their BaNiO 3 and Ni-BaO counterparts, catalysts featuring highly dispersed NiBa demonstrate superior NO decomposition performance under oxygen-containing conditions. At identical heat-treatment temperature, the obtained NiBa catalysts possess more structural defects than the BaNiO 3 and Ni-BaO configurations, manifesting as larger specific surface areas and enriched surface oxygen species. The enhanced redox capability and stronger reactant adsorption of the NiBa catalysts contribute significantly to its improved reaction activity. A nitrate-mediated pathway is proposed to elucidate the high activity of NO decomposition over the NiBa-Y 2 O 3 catalyst, based on combined in situ transmission infrared experiments and density functional theory (DFT) calculations. The mutual reaction between NO molecules or their reaction with surface oxygen generates N atoms, NO 2 ⁻ and NO 3 ⁻, with O 2 molecules serving as an abundant oxygen source. The high-temperature dissociation of NO 3 ⁻ gives rise to O 2 and NO⁻, followed by a direct reaction between NO⁻ and the residual N atom to yield N 2 . However, the oxygen-containing condition preferentially leads to N 2 O formation to generate N 2 . This work provides guidance for developing high-performance catalysts with oxygen resistance for NO decomposition, and advances the fundamental comprehension of the underlying reaction mechanism.