Design and development of smart carbon dioxide sensor

Abstract

A carbon dioxide sensor is a device designed to detect and measure newlinethe concentration of carbon dioxide in various environments. This sensor has newlineextensive applications in fields such as environmental monitoring, industrial newlineprocesses, indoor air quality control, and breath analysis. Monitoring carbon newlinedioxide levels in these scenarios is crucial for minimizing the adverse effects newlineof carbon dioxide on health and the environment. Carbon dioxide sensor newlineoperating at high temperature provides high sensitivity, but the high operating newlinetemperature degrades the sensing material over time and causes drift and newlinecalibration issues. As a result, the overall lifespan of the sensor gets shortened newlineand requires more frequent replacements. This thesis aims to address these newlineconcerns by developing an efficient room temperature operated carbon newlinedioxide sensor capable of detecting and monitoring carbon dioxide levels in newlinevarious environments. We synthesized hierarchical ZnO/CuO nanorods of newlinevarious composite ratios (1:1, 1:2, 2:1) using the hydrothermal method. newlineTesting these composite ratios at room temperature revealed that the 2:1 ratio newlineof ZnO/CuO composite exhibited a remarkable 9.7 % response to 1000 ppm newlineof carbon dioxide gas compared to other ratios. To further improve the newlinesensitivity of the sensing material, noble metal dopants such as silver were newlinedoped into the ZnO/CuO composite. Various concentrations of silver doping newline(ranging from 1 to 5 wt %) were investigated, and the experimental findings newlineshowed that ZnO/CuO nanoflowers doped with 2 wt % Ag exhibited a high newlinesensing response of 18.4 % towards 1000 ppm carbon dioxide gas compared newlineto other doping concentrations. Although the sensing material offers good newlinesensitivity, it exhibits relatively long response and recovery time ranging from newline2.5 to 5.4 minutes. To address this issue, a chemical vapor deposition grown newlinegraphene layer was coated over the 2 wt % Ag-doped ZnO/CuO nanoflowers. newline