ZnO nanorods/Graphene/CNT nanocomposite gas sensors for enhanced VOC gas response and selectivity: Selective analysis of formaldehyde and ethanol

• ZnO nanorods/Graphene/CNT sensor fabricated using the ultrasonic chemical method. • Sensor tested HCHO and C 2 H 5 OH gas responses. • Higher response and sensitivity toward formaldehyde than ethanol. • Samples prepared with varying graphene/CNT ratios (9:1, 8:2, 7:3) In this study, a ZnO nanorods/Graphene/Carbon nanotube (CNT) sensor was fabricated by synthesizing ZnO nanorods through the ultrasonic chemical method, followed by spin-coating with a graphene/CNT composite. Sensors (C1–C3) using ZnO nanorods/Graphene/CNT nanocomposites were prepared with graphene to CNT coating ratios of 9:1, 8:2, and 7:3, respectively, and their response were analyzed. The amount of material deposited during spin-coating more notably influenced the synergic effect of graphene/CNT and ZnO nanorods in sample C1. Sample C1 exhibited a response of 80 for 20 ppm formaldehyde at an operating temperature of 250 °C and displayed selectivity compared with ethanol. Overall, C1 exhibited the strongest reactivity and selectivity toward formaldehyde at 20 ppm.