CO2 sensing properties of semiconducting copper oxide and spinel ferrite nanocomposite thin film

A new active layer for CO2 sensing based on semiconducting CuO–CuxFe3−xO4 (with 0 ≤ x ≤ 1) nanocomposite was prepared by radiofrequency sputtering from a delafossite CuFeO2 target using a specific in situ reduction method followed by post annealing treatment in air. The tenorite–spinel ferrite nanocomposite layer was deposited on a simplified test device and the response in a carbon dioxide atmosphere was measured by varying the concentration up to 5000 ppm, at different working temperatures (130–475 °C) and frequencies (0.5–250 kHz). The results showed a high response of 50% (image) at 250 °C and 700 Hz for a CO2 concentration of 5000 ppm.