Metallic Ti₃C₂T_<i>x</i> MXene Gas Sensors with Ultrahigh Signal-to-Noise Ratio

TLDR

High‑sensitivity solid‑state gas sensors enable precise detection of volatile organic compounds at parts‑per‑billion levels, which is essential for early disease diagnosis. The study aims to achieve high sensitivity by simultaneously minimizing electrical noise and maximizing signal strength, a combination not met by existing sensor materials. Ti₃C₂Tₓ MXene gas sensors, leveraging their metallic conductivity and functionalized surface, achieve a 50–100 ppb detection limit at room temperature and a signal‑to‑noise ratio two orders of magnitude higher than other 2D materials, surpassing the best known sensors.

Abstract

Achieving high sensitivity in solid-state gas sensors can allow the precise detection of chemical agents. In particular, detection of volatile organic compounds (VOCs) at the parts per billion (ppb) level is critical for the early diagnosis of diseases. To obtain high sensitivity, two requirements need to be simultaneously satisfied: (i) low electrical noise and (ii) strong signal, which existing sensor materials cannot meet. Here, we demonstrate that 2D metal carbide MXenes, which possess high metallic conductivity for low noise and a fully functionalized surface for a strong signal, greatly outperform the sensitivity of conventional semiconductor channel materials. Ti3C2Tx MXene gas sensors exhibited a very low limit of detection of 50–100 ppb for VOC gases at room temperature. Also, the extremely low noise led to a signal-to-noise ratio 2 orders of magnitude higher than that of other 2D materials, surpassing the best sensors known. Our results provide insight in utilizing highly functionalized metallic sensing channels for developing highly sensitive sensors.