The adsorption of CO, O2 and H2 on Li–doped defective (8,0) SWCNT: A DFT study

•Li adsorption on the (8,0) SWCNT is stronger nearby a single C vacancy.•Li induces a magnetic moment, a band gap energy reduction and transfers electron density to the CNT.•O2 and H2 molecules dissociates on the CNT while CO adsorbs molecularly.•CO adsorption changes Li+(8,0)SWCNT from magnetic to non magnetic and reduces its band gap.•Li+(8,0)SWCNT becomes non magnetic and shows a metallic behavior after O2 interaction.•After H2 adsorption there is an increase in the band gap energy.