Engineering SnO₂ nanorods/ethylenediamine-modified graphene heterojunctions with selective adsorption and electronic...

Ever-increasing concerns over air quality and the newly emerged internet of things (IoT) for future environmental monitoring are stimulating the development of ultrasensitive room-temperature gas sensors, especially for nitrogen dioxide (NO₂), one of the most harmful air pollution species released round-the-clock from power plants and vehicle exhausts. Herein, tin dioxide nanorods/ethylenediamine-modified reduced graphene oxide (SnO₂/EDA-rGO) heterojunctions with selective adsorption and electronic structure modulation were engineered for highly sensitive and selective detection of NO₂ at room temperature. The modified EDA groups not only enable selective adsorption to significantly enrich NO₂ molecules around the interface but also realize a favorable modulation of SnO₂/EDA-rGO electronic structure by increasing the Fermi level of rGO, through which the sensing performance of NO₂ is synergistically enhanced. The response of the SnO₂/EDA-rGO sensor toward 1 ppm NO₂ reaches 282%, which exceeds the corresponding SnO₂/rGO sensor by a factor of 2.8. It also exhibits a low detection limit down to 100 ppb, enhanced selectivity, and rapid response/recovery kinetics. This approach to designing a novel heterojunction with significantly enhanced chemical and electric effects may shed light on the future engineering of gas-sensing materials.