Construction of organic-inorganic "chelate" adsorption sites on metal oxide semiconductor for room temperature NO sensing.

Metal oxide semiconductors (MOS) have been extensively studied for gas sensing due to their excellent chemical stability and adjustable electronic properties. However, there is still a lack of ingenious design strategies to achieve customizable gas detection in complex environments. Herein, a novel and scalable strategy of constructing organic-inorganic "chelate" adsorption sites is proposed to promote the affinity of MOS sensing materials to target molecules. Specifically, 3-aminopropyltriethoxysilane (APTES)-functionalized reduced graphene oxide (rGO) was decorated on InO tubes (AG/In), and its NO sensing performance was studied. As a result, the optimal AG/In shows boosted room-temperature NO response, and its response to 1 ppm NO is 4.8 times that of InO. More attractively, the optimal AG/In exhibits good selectivity, as well as outstanding detection ability (R/R = 1.6) for low concentration NO (20 ppb). Experimental results suggest that APTES-rGO not only acts as the electron acceptor to accelerate charge transfer, but also enhances NO adsorption. Further theoretical calculations reveal that NO is simultaneously adsorbed at rGO and APTES via a flexible "chelate" mechanism. The multidentate adsorption configuration remarkably strengthens the NO-host interaction, which is conducive to improving sensing performance. This work may inspire the material design of a new generation high-performance gas sensors.