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The effects of B and N dopings and H_2O adsorption on the structural stability and the field emission properties of cone-capped carbon nanotubes(CCCNTs) were investigated by using the density-functional theoretical calculation.The adsorption of H_2O can increase the structural stability and decrease the gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital(HOMO-LUMO gap) of the CCCNTs.The strength of total electric field on the top of the H_2O-adsorbed CCCNTs is larger than that of the B-doped and the N-doped CCCNTs, electrons will be emitted primarily from the H_2O-adsorbed CCCNTs at the same applied voltage.Therefore,the H_2O adsorption can lower the threshold voltage for the CCCNTs.While the B and the N dopings produce opposite effects. The HOMO-LUMO gap of the N-doped CCCNTs is the widest among all the gaps of the CCCNTs.
The effects of B and N dopings and H_2O adsorption on the structural stability and the field emission properties of cone-capped carbon nanotubes (CCCNTs) were investigated by using the density-functional theoretical calculation. The adsorption of H_2O can increase the structural stability and decrease the gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital (HOMO-LUMO gap) of the CCCNTs.The strength of total electric field on the top of the H_2O-adsorbed CCCNTs is larger than that of the B-doped and the N-doped CCCNTs, electrons will be heard primarily from the H_2O-adsorbed CCCNTs at the same applied voltage. Before, the H_2O adsorption can lower the threshold voltage for the CCCNTs.While the B and the N dopings produce opposite effects. The HOMO- LUMO gap of the N-doped CCCNTs is the widest among all the gaps of the CCCNTs.