Room Temperature Real Air Highly Sensitive and Selective\nDetection of Ethanol and Ammonia Molecules Using Tin Nanoparticle-Functionalized\nGraphene Sensors

Graphene,\nwith its high surface area, is an important sensing material\nbut lacks selectivity. As tin oxide has a higher selectivity for ethanol,\nwe fabricated a graphene field-effect transistor (GFET) sensor functionalized\nwith tin nanoparticles (Sn NPs) to enhance its selectivity and sensitivity\nfor ethanol detection. Among 200 nm, 500 nm, 1 μm, and 2 μm\nchannel sizes, 1 nm thickness Sn NPs functionalized on 200 nm GFET\nsensors exhibited high sensitivity and selective detection of ethanol\nand ammonia among five tested gases in a real air environment. Moreover,\nthey demonstrated high sensitivity for ethanol and ammonia, detecting\nconcentrations as low as 100 ppb at room temperature. The postfabrication\nthermal annealing facilitates the formation of Sn NP clusters and\nvoids within the smaller 200 nm graphene channel, contributing to\nthe sensor’s high sensitivity. Furthermore, the catalytic reaction\nof ethanol and ammonia molecules with oxygen molecules in the presence\nof Sn NPs releases electrons, which are reflected in n-doping in the\ngraphene sensor measurements. The potential of this highly sensitive\nand selective ethanol and ammonia detection of graphene sensors can\nbe utilized with machine learning techniques in the sensor cluster\nto identify different gases.