Highly selective ammonia sensing at room temperature using DC plasma-modified MoS2 nanoflowers

Abstract

This study explored the enhancement of ammonia (NH₃) sensing properties of MoS₂ nanoflowers through a direct current (DC) plasma treatment with nitrogen incorporation. Plasma treatment induced sulfur vacancies and introduced nitrogen atoms into the MoS₂ surfaces, enhancing the number of active sites and improving the charge carrier mobility. The structural and chemical alterations were confirmed by characterisations using FE-SEM, XPS, and Raman spectroscopy. The resulting plasma-treated MoS₂ sensor demonstrated highly selective detection of NH₃ at room temperature with a rapid response time of 22 s and a recovery time of 23 s. The experimental limit of detection was achieved at 5 ppm (theoretically ≈ 80 ppb), which was lower than the safety threshold set by the National Institute for Occupational Safety and Health (NIOSH). Results of DFT studies also agreed with the experimental results. Thus, this work highlights DC plasma treatment as an efficient, cost-effective approach to enhance gas sensing performance, with implications for developing highly sensitive and selective sensors for environmental monitoring and safety applications.