In-situ synthesis of stable ZnO-coated CsPbBr3 nanocrystals for room-temperature heptanal sensors

In this work, we coated perovskite quantum dots (CsPbBr 3 ) with metal oxide (ZnO) by an in-situ oxidation strategy to obtain CsPbBr 3 @ZnO nanocrystals , which effectively improved the moisture stability of the perovskite material. In addition, the ZnO layer can also transfer the interaction with gas molecules to the inner CsPbBr 3 , giving the CsPbBr 3 @ZnO nanocrystals good gas-sensing properties at room temperature . This study considered CsPbBr 3 @ZnO films’ structural, morphological, and gas sensing properties; and simulated breath monitoring tests. Later a sensor based on CsPbBr 3 @ZnO nanocrystals was prepared and used to detect the presence of heptanal (a breath biomarker for lung cancer and COVID-19) in different gases, including air, artificial breath, and real breath. The sensor displayed a fairish sensitivity ( S  = 0.36) alongside a brief response/recovery time (36.5 s/5.3 s) towards 200 ppm heptanal prepared with air, and the limit of detection could reach up to 2 ppm in the air and 3 ppm in artificial breath (made up of air, ethanol, isopropanol, 7-tridecanone, and n-tetradecane). Furthermore, the intelligent classification algorithms were used to identified the real breath samples containing heptanal (1–5 ppm) with an 82.5% accuracy rate in simulated breath monitoring tests. Theory calculation results showed that the good response to heptanal was attributed to both the positive adsorption energy (+3 eV) and the increased lattice distortion induced by heptanal. These sensors show great potential to be an effective method for early detection and treatment of lung cancer and COVID-19 for a healthy and prolonged life. We believe that this research will open the door toward more stable and practical perovskite-based sensors.