Configurations for water adsorption on modified CNTs. (A1) Semiconducting CNT with one carbon atom replaced by a boron atom that binds to an H2O molecule, where the boron atom is close to the oxygen atom. (A2) Semiconducting CNT with one carbon atom replaced by one Nitrogen atom binds to an H2O molecule, where the nitrogen atom is close to the oxygen atom. Semiconducting CNT with one carbon atom replaced by a boron atom and another by a nitrogen atom that binds to an H2O molecule, where the boron atom is close to the oxygen atom as in (B1), and the nitrogen atom is close to the oxygen atom as in (B2). (C1) Semiconducting CNT with two carbon atoms replaced by two boron atoms and one by a nitrogen atom that binds to an H2O molecule, where the nitrogen atom is close to the oxygen atom. (C2) Semiconducting CNT with one carbon atom replaced by one boron atom and two others by two nitrogen atoms that bind to an H2O molecule, where the boron atom is close to the oxygen atom. Semiconducting BC2N type 2 nanotube that binds to an H2O molecule, where (D1) BN2 group binds to an H2O molecule with the boron atom close to the oxygen atom, and (D2) B2N group binds to an H2O molecule with the nitrogen atom close to the oxygen atom [43].
