Highly sensitive and room-temperature operable carbon dioxide gas sensor based on spin-coated Sn-doped Co3O4 thin films with advanced recovery properties

Abstract

The urgency to address climate change has highlighted the need for gas sensors capable of monitoring air quality at room temperature (RT) and accurately measuring the concentrations of carbon oxides (CO2 and CO) in the environment. This study details the development of a highly sensitive CO2 gas sensor using spin-coated Sn-doped Co3O4 thin films, operating at a room temperature of 30⁰C and a relative humidity (RH%) of 43 %. Extensive characterization employing XRD, SEM, EDX, FTIR, and UV–Vis optical techniques verified the impact of Sn doping on the surface morphology, phase purity, and a notable reduction in the dual-band gap of the thin films. Gas sensing measurements were conducted at RT using varying CO2 gas concentrations. A sensor response of 796.81 % was obtained for the optimally sensitive film, 10 % Sn-doped Co3O4, at a CO2 concentration of 9990 ppm. Additionally, a range of RH % levels was examined at a constant CO2 gas concentration of 9990 ppm, revealing an optimal humidity level of 43 % at RT. Further analysis revealed that the 10 % Sn-Co3O4 sensor displayed enhanced sensitivity to CO2, surpassing its response to N2, H2, and NH3 gases. The determined limits of detection and quantification underscore the sensor's precision and reliability in quantifying CO2 gas concentrations. Our findings demonstrate the excellent potential of Sn-doped Co₃O₄ thin films as highly sensitive CO₂ gas sensors. These films provide a promising solution for detecting elevated CO₂ levels at room temperature, aiding climate change mitigation efforts.