Room-temp trace ammonia detection using SnS2 nanosheets@PANI composite: a step towards ultrasensitive environment monitoring and non-invasive renal disease diagnosis

Abstract

Selective and rapid detection of ammonia (NH₃) gas over a wide concentration range is essential for applications such as early diagnosis of renal diseases and environmental safety. NH₃ in exhaled breath serves as a biomarker of kidney function, and its precise detection is vital for early renal disease diagnosis. This work reports a SnS₂/PANI heterojunction nanocomposite (SPA) sensor synthesized via a hydrothermal route followed by in situ oxidative polymerization. The layered SnS₂ nanosheets were surface-modified with sodium dodecyl sulfate (SDS) to promote Na⁺ ion intercalation, thereby enhancing exfoliation and reducing agglomeration, as confirmed by FESEM, TEM, Raman, and UV-VIS spectroscopy. Among all nanocompositions, the SPA75 sensor exhibits the best performance, detecting NH₃ from 0.5 to 150 ppm at 30 °C and 69% RH, with a maximum relative response of 213% at 150 ppm NH₃, a limit of detection of 0.5 ppm, and ultrafast response/recovery times of 18/64 s. The SPA75 sensor also delineates promising results towards healthy and simulated breath. The enhanced sensing performance is attributed to efficient charge transfer at the heterojunction interface. In addition, the large surface area and mesoporous nature of SPA75 (37.475 m² g⁻¹) facilitate gas adsorption and diffusion, further contributing to its high efficiency. These results establish SPA75 as a highly efficient material for ultrasensitive NH₃ detection in environmental monitoring and real-time exhaled breath analysis for renal disease diagnosis.