Role of cobalt in Co-ZnO nanoflower gas sensors for the detection of low concentration of VOCs

As a non-invasive detection method, breath analysis for the diagnosis of lung cancer has been a hotspot in the medical field. Using an electronic nose to achieve the breath analysis is a popular choice. Herein, cobalt-ZnO sensors which have high response to low concentration volatile organic compounds were fabricated as sensors in electronic noses for the diagnosis of lung cancer. The Co-ZnO samples were synthesized via wet chemical method and drop coated onto the alumina substrates equipped with gold interdigitated electrodes after calcination. The as-synthesized materials were characterized by SEM/EDX, XRD, FT-IR and XPS to observe their microstructure, crystal phase, and electronic state of Co atom in the samples. The sensors were tested with various VOCs at different temperatures using artificial breath. At the same time, the stability of the sensor was tested. The sensor showed different optimal temperatures and target gas with different amounts of Co2+ addition. The improvement in the sensing performance could be explained by the different phases of Co in the sensing layers.