The correlation of NO chemisorption adsorption with its directly catalytic dissociation pathway on β-MnO₂(1 1 0) and (1 0 1) surfaces

MnO₂-based oxide catalysts have recently drawn so much attention owing to its good catalytic activity for NOx direct catalytic decomposition at low-temperature. As the reaction mechanism of NO direct catalytic decomposition on different MnO₂ surfaces is not yet clear, it is important to understand the influence of different crystal surfaces of β-MnO₂ on catalytic activity for NO decomposition. The correlation of NO chemisorption with its dissociation pathways on β-MnO₂(1 1 0) and (1 0 1) surfaces are investigated based on density functional theory (DFT) with Vienna Ab-initio Simulation Package (VASP). The calculation results have shown that NO prefers to be adsorbed on β-MnO₂(1 1 0) instead of β-MnO₂(1 0 1) surface. The analysis results of density of states and differential charge density indicate that the interaction between NO and β-MnO₂(1 1 0) surface is stronger and the adsorbed NO had more charge transfer with β-MnO₂(1 1 0) surface. The effective activation energies of the possible NO dissociation pathways on the β-MnO₂(1 1 0) and (1 0 1) surfaces are 2.57 and 3.07 eV, respectively. The lower energy barrier on β-MnO₂(1 1 0) must be associated with the bridge adsorption of NO and more electrons transfer from NO to the surface, which is conducive to the breaking of N-O bond.