Gas sensing properties of porphyrin thin films influenced by their surface morphologies

Abstract

Two different thin film fabrication techniques, namely Langmuir-Blodgett (LB) and Spin Coating (SC), have been used to fabricate homogeneous nanoscale thin films of metal free 2, 3, 7, 8, 12, 13, 17, 18-Octaethyl-21H, 23H-porphine and its derivatives containing iron chloride, cobalt and magnesium. The gas sensing properties of these thin films towards volatile organic compounds such as chloroform, benzene, toluene and methanol have been investigated using a Surface Plasmon Resonance (SPR) System. Additionally, Atomic Force Microscopy (AFM) has been employed to investigate their surface morphology. The gas sensing properties have been analyzed in terms of gas sensing influencing mechanisms such as Coulombic/Van Der Waals and reduction-oxidation interactions or central metal atom effects. The presented results show that the gas sensing performances of the SC thin films are higher than those exhibited by the ones assembled by LB. The level of interaction with the analyte gas molecules has been observed to be higher in the case of the thin films exhibiting larger surface areas.