In-situ mechanochemically tailorable 2D gallium oxyselenide for enhanced optoelectronic NO₂ gas sensing at room...

The adverse effects of NO₂ on the environment and human health promote the development of high-performance gas sensors to address the need for monitoring. Two-dimensional (2D) metal chalcogenides have been considered an emerging group of NO₂-sensitive materials, while incomplete recovery and low long-term stability are the two major hurdles for their practical implementation. The transformation into oxychalcogenides is an effective strategy to alleviate these drawbacks, but usually requires multiple-step synthesis and lacks controllability. Here, we prepare tailorable 2D p-type gallium oxyselenide with the thicknesses of 3-4 nm, through a single-step mechanochemical synthesis that combines the in-situ exfoliation and oxidation of bulk crystals. The optoelectronic NO₂ sensing performances of such 2D gallium oxyselenide with different oxygen contents are investigated at room temperature, in which 2D GaSe_0.58O_0.42 exhibits the largest response magnitude of 82.2% towards 10 ppm NO₂ at the irradiation of UV, with full reversibility, excellent selectivity, and long term stability for at least one month. Such overall performances are significantly improved over those of reported oxygen-incorporated metal chalcogenide-based NO₂ sensors. This work provides a feasible approach to prepare 2D metal oxychalcogenides in a single-step manner and demonstrates their great potential for room-temperature fully reversible gas sensing.