SnO<inf>2</inf>Nanoparticle-Reduced Graphene Oxide Hybrids for Highly Selective and Sensitive NO<inf>2</inf>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.