CsPbBr3@TiO2 Heterojunction Microcrystals Gas Sensor for Low-Concentration H2S Stability Monitoring at Room Temperature
Through a simple solution method,TiO(Acac)2 was used to in-situ coat the all-inorganic perovskite material CsPbBr3.After heating at 400 ℃,CsPbBr3@TiO2 core-shell structure microcrystals were directly prepared.The crystal structure,microscopic morphology,and chemical composition of CsPbBr3@TiO2 microcrystals were characterized using X-ray diffraction(XRD),scanning electron microscopy(SEM),high-resolution transmission electron microscopy(HRTEM),and X-ray photoelectron spectroscopy(XPS).It was confirmed that the in-situ metal oxide coating on the perovskite formed well-dispersed spherical shell structures with sizes of 4～8 µm.A CsPbBr3@TiO2 thin film gas sensor was constructed on a fluorine-doped tin oxide(FTO)electrode using spin-coating method.The sensitivity of the sensor to H2S gas was tested at room temperature.The results show that the sensor has a detection limit of 25 ppb(1 ppb=10-9)for H2 S gas,with a response and recovery time of 24/21 s to 100 ppb H2S,and a sensitivity of 0.59.The response curve exhibits good cyclic stability.Moreover,the sensor maintains over 90％stability within 30 d of exposure in air and possesses excellent gas selectivity and humidity resistance.Photoluminescence(PL)spectroscopy,time-resolved photoluminescence(TRPL)spectroscopy,ultraviolet-visible diffuse reflectance spectroscopy(UV-Vis),and ultraviolet photoelectron spectroscopy(UPS)were employed to analyze the band positions,charge dynamics,and coordination mechanisms.The sensing mechanism was elucidated using the oxygen adsorption principle.This work provides a new approach for the stable monitoring of low concentrations of H2S gas at room temperature.
CsPbBr3perovskitecore-shell structureheterojunctionH2S gas sensoroxygen adsorption principle
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