Promotional effect of nitrogen-doping on a ceria unary oxide catalyst with rich oxygen vacancies for selective catalytic reduction of NO with NH3

•The N-doped ceria catalyst was prepared by NH3-annealing method.•Oxygen vacancies, Brønsted acid sites and active nitrites were enriched after nitrogen-doping.•Inhibition of NH3 oxidation promoted the SCR activity of the N-doped ceria.