Enhanced Room-Temperature Ammonia Sensing Using Oxygen-Rich Ti ₃ C ₂ T _x MXene Decorated with Silver Nanoparticles (Ti ₃ C ₂ T _x @Ag NPs)

Abstract

Two-dimensional MXenes have garnered significant attention in gas sensing due to their high surface area, tunable surface chemistry, and excellent electrical conductivity. However, enhancing their gas-sensing performance without foreign composites remains challenging. This study presents a facile strategy for synthesizing an oxygen-rich Ti 3 C 2 T x MXene modified with uniformly dispersed silver nanoparticles (Ag NPs) via chemical etching followed by an immersion reduction process. The incorporation of Ag NPs significantly improves the NH 3 sensing performance at room temperature. Comprehensive material characterization, including SEM, EDS, XRD, and XPS, confirmed the successful deposition of metallic Ag nanoparticles (20–50 nm) without disrupting the MXene layered structure. The optimized Ti 3 C 2 T x @Ag sensor exhibited a markedly enhanced response to NH 3 , achieving a maximum response value of 35.5, more than double that of the pristine MXene, along with excellent reversibility, linear response across a broad concentration range (0–700 ppm), and outstanding selectivity against interfering gases such as CO 2 and CH 4 . The enhancement mechanism is attributed to the synergistic effects of abundant oxygen-containing functional groups on MXene, which facilitate NH 3 adsorption, and the catalytic role of Ag NPs in promoting oxygen dissociation and increasing active surface sites. This work provides a viable pathway for developing high-performance, low-power gas sensors for applications in environmental monitoring and industrial safety.