Gas Sensitivity Improvements of Nanowire Hexadecafluorinated Iron Phthalocyanines by Thermal Vacuum Annealing

In the quest for more sensitive gas sensors, researchers have studied how heating the sensors, using UV light, and thermally annealing sensors improve performance. During thermal annealing, the heating process can improve the crystallinity of the material while also increasing the electrode and sensing material interactions to create more available active sites and thus improve sensor performance. Hexadecafluorinated iron (II) phthalocyanine (FePcF16) nanowires have high sensitivity towards NH3 selectively, and thermally annealing the NWs after the deposition can further improve the sensing response and recovery. For this reason, the effect of annealing FePcF16 NWs at different temperatures was studied to optimize these systems. In this work, FePcF16 NWs were synthesized using physical vapor deposition (PVD) to deposit on interdigitated electrodes. The NWs were characterized by SEM, EDS, PXRD, FTIR, and Raman spectroscopy to confirm their purity. The sensors were annealed at different temperatures, inserted into a gas sensing chamber, and exposed to 1 ppm NH3 in air, and the electrical current was measured. The results show that the optimized FePcF16 NWs have excellent sensing properties, with a 58% increase in response towards NH3 after a stepwise annealing at 300 °C confirming these systems are good prospective candidates for sensing NH3 at room temperature.