Mohammadi et al. reported the fabrication of P-doped CNT through CVD method involving the thermal treatment of CNT with triphenyl phosphine at 600 °C for 1 h along with the flow of Ar gas using Fe/CaCO3 as the catalyst . The synthesized P-doped CNT was explored as electrocatalyst for ORR in basic medium. The heteroatom doped graphene and CNTs prepared via CVD method with various precursors are summarized in Table .