Cadmium Oxide Based Nanomaterials Assembly And Gas Sensing Performance

In this paper, the hierarchical flower- and wire-like CdO nanostructural materials were prepared by chemical bath deposition and hydrothermal methods, while the Ag-CdO, ZnO-CdO and In2O3-CdIn2O4 composites were prepared by UV irradiation reduction, solvothermal and sol-gel methods, respectively. These materials were characterized by XRD, SEM, TEM, XPS, BET, IR and TG techniques. Thick film-type gas sensors for all the materials and thin film-type gas sensors for wire-like CdO nanomaterials were fabricated and their gas sensitivities to ethanol, acetone, alkanes, benzene, toluene and NO were measured.The sensitivity of sensor based on hierarchical CdO flowers to 1000μL/L ethanol at 485℃is 1.73. It could detect ethanol concentration as low as 500μL/L with the rapid response and recovery time of 20 s. After loaded silver nanoparticles, the sensitivity to 1000 p.L/L ethanol could improve to 5.78. By contrast, the sensitivity of sensor based on hierarchical CdO wires to 1000μL/L ethanol at 410℃is 5.6. It can detect ethanol concentration as low as 250μL/L. The operating temperature can reduce to 310℃after loaded Ag nanoparticles. Especially, the thin film sensor based on the hierarchical CdO wires could detect the gas concentration of ethanol as low as 50μL/L with the operating temperature of 250℃. The ZnO-CdO composites with 26.34% ZnO exhibit good selectivity to 1000μL/L acetone with sensitivity of 10.89 at 250℃. Moreover, the In2O3-CdIn2O4 composites with 12.21% Ln2O3 show the best sensitivity (63.4) and selectivity to 1000μL/L ethanol at 330℃.