Lead-Free Halide Double Perovskite CsAgBiCl for HS Trace Detection at Room Temperature.

Hydrogen sulfide (HS) is an important respiratory biomarker of many diseases, and thus, developing HS 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, CsAgBiCl was synthesized using a simple method. The sensor based on CsAgBiCl showed excellent sensing of HS gas at room temperature over a wide humidity range, with high response (90.6 vs 10 ppm of HS) and fast response speed (99.6 s vs 400 ppb HS). The detection limit was low (5 ppb HS), and the selectivity at room temperature was excellent. Small changes in HS 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 HS at Cl vacancies on the surface of CsAgBiCl, 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.