Stable N-doped Ti3C2Tx gas sensors for recoverable detection of ammonia at room temperature

Abstract

Herein, highly recoverable, and stable, nitrogen-doped Ti3C2Tx-based sensors are developed for ammonia detection at room-temperature. Ti3C2Tx MXene as a room-temperature gas sensor has two main drawbacks: weak recovery and resistance drift. In this work; Ti3C2Tx nano-sheets were derived from the pre-synthesized Ti3AlC2 by selective aluminum etching using HF acid. The sensors fabricated using pristine Ti3C2Tx had high response toward polar gases, particularly ammonia. The sensors’ response to 100 ppm ammonia was 10%. However, they experienced incomplete recovery and baseline resistance drift. To overcome these problems, we introduced a novel method, in which, before fabricating the gas sensors, the surface of synthesized Ti3C2Tx MXene was modified by a nitrogen treatment strategy. In this method, the MXene layers were doped with nitrogen using NH3 gas at 500 °C for 2 h. In nitrogen-doped Ti3C2Tx-based sensors, both recovery and drift problems disappeared. The response of the nitrogen-doped Ti3C2Tx is 3.7% toward 100 ppm ammonia, which is a notable response for a stable, recoverable, room-temperature gas sensor.