Enhanced CO2 sensing with In2O3-ZnO and SnO2-ZnO composite nanostructures

• In 2 O 3 -ZnO and SnO 2 -ZnO nanostructures were prepared. • Electron beam evaporation technique was used for thin film fabrication. • UV–vis studies showed that the prepared nanostructures had wide band gap. • The thermal and electrical conductivity of the materials lead to the thermoelements application. • In 2 O 3 -ZnO and SnO 2 -ZnO heterostructures demonstrated high sensitivity Co 2 gas sensing. This study explores the synthesis and characterization of In 2 O 3 -ZnO and SnO 2 -ZnO nanostructures for enhanced CO 2 gas sensing. A sol–gel approach was employed to fabricate unique nanostructures, followed by chemical co-precipitation and electron beam evaporation to produce thin films. Structural and morphological analyses, utilizing XRD and TEM, revealed a polycrystalline nature with nanocrystalline sizes ranging from 30 to 45 nm. An optimal indium-zinc ratio of 3:1 significantly influenced gas sensing performance. The In 2 O 3 -ZnO and SnO 2 -ZnO heterostructures demonstrated high sensitivity (80–90 %) towards 200–300 ppm CO 2 gas at relatively low operating temperatures (80–90 °C), with rapid response and recovery times. The SnO 2 -ZnO sample exhibited superior performance for various CO 2 concentrations, achieving maximum sensitivity at 280 °C. A plausible gas-sensing mechanism involving the interaction of CO 2 molecules with the nanostructure surface was proposed. This study highlights the potential of In 2 O 3 -ZnO and SnO 2 -ZnO nanostructures for developing advanced CO 2 gas sensors with applications in environmental monitoring, indoor air quality control, and breath analysis. This study examines the effects of doping with ZnO nanocomposites of SnO 2 and In 2 O 3 for CO 2 sensors, which serve as a representation of the research methodologies used by experts and research organizations.