Development of graphene coated nanostructures for indoor carbon dioxide gas sensing

Developing highly efficient room temperature carbon dioxide (CO₂) sensor is crucial for diverse environmental and industrial applications. Semiconductor-based CO₂ gas sensors stand as pivotal technology in this pursuit. In this study, we employed Chemical Vapor Deposition (CVD) grown few-layer graphene sheets coated Ag-ZnO/CuO nanostructure for carbon dioxide detection. A comprehensive analysis employing transmission electron microscopy, scanning electron microscopy, and x-ray diffractometer was conducted to analyse the morphological and crystal structure of the sensing material. Furthermore, X-ray photoelectron spectroscopy and Atomic force microscopy were utilized to confirm the elemental composition, chemical states, and surface roughness properties of the sensing material. The experimental evaluation of these graphene coated nanostructure on CO₂ concentrations ranging from 150 to 1000 ppm at room temperature (25 °C), revealed a notable sensing response of 21% toward 1000 ppm of CO₂ gas. Also, the sensor demonstrated exceptional response and recovery times of less than 2 min. Additionally, the sensing material displayed good repeatability and high selectivity towards CO₂ gas. Moreover, we also developed a Smart CO₂ sensor by integrating with an ESP32 microcontroller and tested it for real-time indoor air quality monitoring applications.