Preparation of CsPbBr3@Fe2O3 heterojunction nanocrystals for ppb-level H2S sensing

Metal-halide perovskite (MHP) nanocrystals (NCs) have unique advantages in the gas sensing field, but the poor stability restricts their widespread applications. In this work, the CsPbBr3@Fe2O3 heterojunction NCs were synthesized successfully by simple solution process and subsequent surface modification strategy for constructing a gas sensor. The Fe2O3 shell layer was obtained through thermal decomposition of acetylacetone iron (AAI) at 400 °C. The resulting CsPbBr3@Fe2O3 heterostructured NCs exhibit a higher gas-sensing performance to H2S than pure CsPbBr3 and Fe2O3, respectively. Upon exposure to 10 ppm H2S, the response value of 4.12 was obtained at a moderate working temperature of 350 °C, while the response was fast both in terms of response time and recovery time, i.e., 1.84 s and 24.20 s, respectively. This might be the best performance for MHP sensors, to the best of our knowledge. The excellent gas-sensitive response might be attributed to the formation of a heterojunction which promotes the electron migration from CsPbBr3 to Fe2O3.