Surface acoustic device for high response NO ₂ gas sensor using <i>p</i> -phenylenediamine-reduced graphene oxide nanocomposite coated on langasite

Abstract

Abstract In this study, we fabricated a surface acoustic wave (SAW) device using a langasite (LGS) substrate. The p -phenylenediamine-reduced graphene oxide (PrGO)-coated LGS substrate resulted in high response sensor systems for very short time scale detection of NO 2 and CO. With the catalytic reaction of PrGO, the resonant frequency of 100 ppm of NO 2 gas changed by ∼3.50 kHz, which is nearly eight times higher than that of the pristine LGS SAW device. Further, we conducted selectivity tests for NO, NH 3 , H 2 S, and CO gases; the results showed that the PrGO-coated LGS had higher selectivity for NO 2 compared to other gases. Accordingly, the underlying mechanism for the superior NO 2 sensing was discussed in relation to the morphological characteristics and configuration of PrGO. In addition, the effect of humidity on the SAW performance was studied under ambient NO 2 .