Ultrasensitive sensing of hydrazine vapor at sub-ppm level with pyrimidine-substituted perylene diimide film device

Abstract

A pyrimidine-substituted perylene diimide (Pyrimidine-PDI), in which the electron-deficient N-heterocyclic pyrimidine rings were introduced into the core positions, were synthesized to produce a conductometric film device for the sensitive detection of hydrazine (NH2NH2) vapor at room temperature under ambient conditions. The Pyrimidine-PDI film device exhibited ultrafast response, excellent reproducibility, excellent selectivity and good long-term stability towards hydrazine vapor. The response and recovery time of the device was calculated to be very low as 0.4 s and 0.6 s for hydrazine vapor at sub-ppm level (0.1 ppm). Moreover, the effect of the film thickness, relative humidity and temperature on the sensing performance were also studied. To understand the sensing mechanism, the core-benzene group perylene diimide (Ph-PDI) was also designed as a comparison. The film devices of Pyrimidine-PDI and Ph-PDI to hydrazine vapor were investigated with UV–vis spectra and cyclic voltammetry, which indicated that the redox of PDIs played a critical role in the sensing process. The electrochemical properties also indicated that electron-deficient N-heterocyclic pyrimidine rings could effectively lower the LUMO energy level and improve the response of the device.