Advanced sensing materials are in high demand for sensitive, real-time, and continuous detection of gas molecules for gas sensors, which have been becoming an effective tool for environmental monitoring and disease diagnosis. Cobalt-containing spinel oxides are promising sensing materials for the gas-sensing reaction owing to their element abundance and remarkable activity. Structural and component properties can be modulated to optimize the sensing performances by substituting Co with other transition metals. Herein, a systematic study of spinel MCo₂O₄ oxides (M = Mn, Ni, and Zn) toward gas sensing is presented. Results show that ZnCo₂O₄ materials with a multishelled hollow twin-sphere structure obtained excellent sensing performances to formaldehyde and acetone at different temperatures. The replacement of Co with Zn in the lattice improves the oxygen-chemisorbing ability, which allows new opportunities to synthesize and design highly sensitive chemical sensors.

KEYWORDS: spinel oxides; gas sensing; hollow; ZnCo₂O₄; highly sensitive