A Review of Carbon Nanotubes-Based Gas Sensors

Table 3

Calculated data for adsorption of H₂O on the doped carbon nanotubes or B_xC_yN_z Nanotubes [43].

	𝐸𝑔 (eV)^f	Configuration	𝐸𝑏 (eV)	𝐷 (Å)	𝐸𝑇 (el)^g
CNT	0.56	H2O	no binding
B-CNT^a	0.44	B-H2O^h	−0.56	1.70	−0.12
N-CNT^b	0.43	N-H2O^i	−0.23	3.12	−0.02
BN-CNT^c	0.48	B-H2O	−0.48	1.72	−0.20
		N-H2O	−0.24	3.14	−0.02
B2N-CNT^d	0.44	N-H2O	−0.64	3.15	−0.28
BN2-CNT^e	0.42	B-H2O	−0.53	1.51	−0.08
BC2N-type 2	0.93	B-H2O	−0.48	1.72	−0.21
		N-H2O	−0.18	3.14	−0.05

^aIntrinsic nanotube doped with boron atom in 2-unit cell.
^bIntrinsic nanotube doped with nitrogen atom in 2-unit cell.
^cIntrinsic nanotube doped with boron-nitrogen atom pair in 2-unit cell.
^dIntrinsic nanotube doped with boron-nitrogen-boron atom pair in 2-unit cell.
^eIntrinsic nanotubes doped with nitrogen-boron-nitrogen atom pair in 2-unit cell.
^fHOMOLUMO band gap.
^gElectron charge transfer from the nanotube to molecules.
^hH₂O molecule binds to the nanotube with the oxygen atom close to the boron atom.
ⁱH₂O molecule binds to the nanotube with the oxygen atom close to the nitrogen atom.