Cs₂AgBiBr₆ Quantum Dots Supported on Co₃O₄ Nanocages for Acetone Detection at Room Temperature

High operating temperatures have been one of the most serious problems restricting the development of metal oxide gas sensors. The development of room temperature (RT) sensing is significant in practical applications. Herein, for the first time, we combined environmentally friendly lead-free double perovskite photovoltaic material Cs₂AgBiBr₆ quantum dots (CABB QDs) (9–13 nm) with MOF-derived Co₃O₄, and mesoporous heterogeneous composite materials (average pore diameter about 17.58 nm) with a series of weight percentage (wt %) CABB QDs supported on Co₃O₄ nanocages were prepared by the template and heat treatment method. The gas sensing test results indicate that adding photovoltaic material CABB QDs can achieve high-performance acetone sensing at RT (25 °C). Especially, the sensor based on 2.0 wt % QDs-Co₃O₄ exhibited the highest gas-sensitive response to acetone, with a response value of 13 at 60 ppm and a fast response and recovery time of 7 and 27 s, respectively. Meanwhile, the 2.0 wt % QDs-Co₃O₄ sensor showed good selectivity, repeatability, and long-term stability. In addition, we delved into the sensing mechanism of acetone’s high response and selectivity at RT. This work provides a constructive idea for the detection of acetone at RT and has significant implications for accelerating the practical application of MOS-based gas sensors.