Ordered 2D Gold Nanoparticle\nFilms for Sensing of\nToluene and Ethanol Gases

The use of metallic nanoparticles as building blocks\ntoward the\nsynthesis of self-assembled films creates intriguing opportunities\nfor generating advanced materials with multifunctional properties.\nTo achieve that, uniformed gold nanoparticles protected by alkanethiols\nhave been used to form highly ordered two-dimensional (2D) monolayer\nfilms at the air/water interface with the aid of the Langmuir–Blodgett\ntechnique. These films display a highly ordered hexagonal close-packed\nstructure with controlled interparticle distance at 1.3 ± 0.45,\n1.9 ± 0.65, and 2.2 ± 0.64 nm, respectively, by changing\nthe chain length of alkylthiol ligands. Further investigation suggests\nthat the driving force of the formation of ordered 2D nanoparticle\nfilms is the van der Waals force, which is exponentially decreased\nwith the increase of the chain length of alkylthiol ligands. Significantly,\ntheir optical, adhesive, hydrophobic, and electric properties can\nalso be varied by changing the chain length of alkylthiol ligands.\nBased on their excellent performances, they have been used for designing\nvapor sensors to detect toluene and ethanol gases, which have been\nfound to possess excellent stability, appreciable recovery time, and\nmuch lower LOD than other sensing systems. Besides, important parameters\nof these nanoparticle films have been obtained, including active energy,\nelectrical conductivity, and contact angle. In summary, our research\nprovides an effective way for preparing uniformed hydrophobic gold\nnanoparticles and forming highly ordered 2D hexagonal close-packing\nfilms via regulation of nanoparticle interactions during self-assembly,\nand these films not only have excellent multiple performances but\nalso have many promising applications, such as sensors.