B/N co-doped carbon supported molybdenum carbide catalysts with oxygen vacancies for facile synthesis of flavones through oxidative dehydrogenation

•B/N co-doped carbon supported Mo2C catalysts with oxygen vacancies were prepared.•The oxidative dehydrogenation of flavanones to flavones was performed smoothly.•The synergistic effect between Mo2C and oxygen vacancies results in good yields.•β-Mo2C can greatly reduce the activation energy of flavanone dehydrogenation.•O vacancies could activate O2 with the dissociated H atom to generate ·OH radicals.