TITLE:
Different Interaction Mechanisms of Evaporated Porphyrin Films Exposed to NO2
AUTHORS:
M. Rivera, M. Rivera, J. M. Rivera, O. Amelines-Sarria, Y. A. Wang
KEYWORDS:
Porphyrin Films, Vacuum Evaporation, NO2, Gas Sensor, Density Functional Theory
JOURNAL NAME:
Advances in Materials Physics and Chemistry,
Vol.8 No.11,
November
16,
2018
ABSTRACT:
In this work, metal free and zinc tetraphenylporphyrin films were
employed as nitrogen dioxide (NO2) gas
sensors. The films were vacuum evaporated and the sensor response was evaluated
as changes in the optical absorption spectra, hydrophobic properties and
conductivity at different gas concentrations. From UV-Vis results,
important changes in the absorption peaks were observed after gas exposure. The
morphology of the films before and after gas interaction was obtained by using
scanning electron and atomic force microscopy. The films morphology showed a
degradation after gas adsorption for the metal free system but gas entrapment
for the zinc porphyrin film. In order to elucidate the gas adsorption
phenomena, density functional theory calculations were also performed. Here, it
was observed that the porphyrin chemical structure not only affects the gas coordination
sites which affect the porphyrin electronic distribution and packing
arrangement, but also, determines the gas detection mechanism for sensing
applications.