Cu 2 O quantum dots modified by RGO nanosheets for ultrasensitive and selective NO 2 gas detection

Abstract Real-time monitoring of trace NO 2 emission has been an emerging challenge in environment and health sectors lately. Aiming to overcome this challenge, NO 2 gas sensors based on cuprous oxide quantum dots (Cu 2 O QDs) anchored onto reduced graphene oxide (RGO) nanosheets serving as a sensitive layer were prepared in this report. Apart from a series of purposive measurements, various characterization techniques such as XRD, Raman, XPS and TEM were employed as well to assist the exploration of sensors performance to NO 2 gas. The experimental results revealed a 580% response enhancement for prepared RGO/Cu 2 O sensors compared with pure RGO counterparts, as well as an excellent selectivity. In a specific experiment, the sensing response attained 4.8% and 29.3% toward 20 ppb and 100 ppb NO 2 respectively at 60 °C, which was larger than most Cu 2 O based resistive gas sensors. Moreover, further subtle modulation of this RGO/Cu 2 O nanocomposites led to a preferable room-temperature response of 37.8% toward 100 ppb NO 2 , which also offered a favorable stability of 98.1% response retention after four exposures within ten days. The obtained results imply that the prepared RGO/Cu 2 O QDs sensors possess a competitive capability of trace NO 2 detection.