(a) Dynamic acetone-sensing
transition in the concentration range
1–5 ppm of acetone at 450 °C. (b) Selective acetone-sensing
characteristic of the double-Co3O4 rods@ZnO
sheet against interfering analytes (H2S, CO, toluene, HCHO,
NO, and NH3) at a concentration of 5 ppm at 450 °C.
(c) Pattern recognition based on PCA using sensor arrays. (d) Suggested
sensing mechanism toward acetone. (e) XPS spectra of double-Co3O4 rods@ZnO sheet: O 1s. (f) Pore distribution
of Co3O4 rods, ZnO sheet, single-Co3O4 rods@ZnO sheet, double-Co3O4 rods@ZnO
sheet, and triple-Co3O4 rods@ZnO sheet.