Abstract: A sensing film configured to detect an analyte gas includes a metal oxide thin film and noble metal nanoparticles disposed on the metal oxide thin film. The sensing film can be a compressed thin film of metal oxide nanostructures. Forming the sensing film includes dispersing the multiplicity of hydrophobic metal oxide nanostructures onto a surface of a layer of water to yield a thin film of the hydrophobic metal oxide nanostructures on the water. The hydrophobic metal oxide nanostructures have a common orientation with respect to the surface of the water. The thin film of the hydrophobic metal oxide nanostructures are compressed to yield a compressed thin film of the hydrophobic metal oxide nanostructures.