Lead-Free Halide Double Perovskite Cs<sub>2</sub>AgBiCl<sub>6</sub> for H<sub>2</sub>S Trace Detection at Room Temperature
Menglong Li, Wen Ye, J. Ruan, Qiuyuan Ren, Shihong Dong, Dongyun Chen, Najun Li, Qingfeng Xu, Hua Li, Jianmei Lu
Abstract
Hydrogen sulfide (H 2 S) is an important respiratory biomarker of many diseases, and thus, developing H 2 S gas sensors with low detection limits at low operating temperatures is essential for the early diagnosis of diseases in low-resource environments. Although lead halide perovskites have unique electronic and optical properties, the high toxicity of lead has prompted the development of alternative materials. In this study, Cs 2 AgBiCl 6 was synthesized using a simple method. The sensor based on Cs 2 AgBiCl 6 showed excellent sensing of H 2 S gas at room temperature over a wide humidity range, with high response (90.6 vs 10 ppm of H 2 S) and fast response speed (99.6 s vs 400 ppb H 2 S). The detection limit was low (5 ppb H 2 S), and the selectivity at room temperature was excellent. Small changes in H 2 S concentration (<100 ppb) were detected as a fully reversible resistance signal. Additionally, sum frequency vibration spectroscopy and DFT calculations showed that the high gas sensitivity was attributed to the physical adsorption of H 2 S at Cl vacancies on the surface of Cs 2 AgBiCl 6, as well as efficient charge transfer. This work provides an avenue for developing high-performance gas sensors based on nontoxic, wide band gap, halide double perovskite semiconductors operating at room temperature.