SnO₂ Nanoparticle-Reduced Graphene Oxide Hybrids for Highly Selective and Sensitive NO₂ Sensors Fabricated Using a Component Combinatorial Approach

The combinatorial design of sensors has been demonstrated as an effective strategy for rapidly screening sensing materials and optimizing functional parameters for high-performance sensors. In this work, we report the development of room-temperature NO2 sensors based on a SnO2–rGO composite following a componential combination approach. SnO2–rGO is synthesized via a single-step solvothermal technique, and the resulting product is separated into different layers using the Differential Centrifugation technique. Different components were used for fabricating individual chemiresistive devices and studied together by a combinatorial approach using a 2 × 2 sensor array. Among all the devices, the L1-based nanohybrid device exhibited a significant response of ∼3 to a low concentration of 80 ppm NO2 at room-temperature operation and fluctuating humidity (20–50% RH) at much faster speeds ∼5.6 s and recovered quickly in 14.1 s without heating. Also, the SnO2–rGO hybrid resulted in a highly selective, repetitive and reproducible response with an RSD of ∼0.9% for NO2 with a negligible response to interfering gases/VOCs at room temperature. The excellent NO2 sensing properties are due to enhanced gas interaction, fast charge transport, and electrostatic attraction upon forming the SnO2–rGO heterostructure facilitated by the Sn–C covalent bond.