Electron Transport and CO Sensing Characteristics of Fe(II) Porphyrin with Single-Walled Carbon Nanotube Electrodes

Electron transport and carbon monoxide (CO) sensitive characteristics of Fe(II) porphyrin (PP-Fe) with two single-walled carbon nanotube electrodes (SWCNTs) were studied using nonequilibrium Green’s function (NEGF) formalism combined first-principles density functional theory (DFT). When PP-Fe is connected to SWCNT electrodes in diagonal configuration, owing to the fact that the electron passes through the Fe center, it shows higher CO sensitivity than that in para connection mode. Meanwhile, the PP-Fe sensor with armchair SWCNTs is more sensitive to CO than that in zigzag junction, since the coupling interaction between central molecule and armchair SWCNT electrodes is stronger. The PP-Fe sensor anchored on armchair SWCNTs in diagonal configuration can reach a current on–off ratio of 2.1 × 104 in response to the chemisorption of CO, showing better CO sensitive characteristics than that with zigzag SWCNTs and metallic electrodes. With the development of experimental techniques, it is completely possible to fabricate this kind of CO sensor by experimental means.