Hydrothermal synthesis of one-dimensional α-MoO₃ nanomaterials and its unique sensing mechanism for ethanol

In gas sensor applications, the availability of highly sensitive and rapid response/recovery detector for ethanol gas is sparse. One-dimensional orthogonal crystalline molybdenum trioxide nanomaterials were synthesized by an economical and environmentally friendly hydrothermal method. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy spectroscopy (EDS) were used to investigate the structure and morphology of the nanometer materials. The relevant characterization shows that nanobelts are highly crystalline layered structures with a width of about 200 nm and a length of a few micrometers. The synthesized ethanol gas sensors based on α-MoO₃ semiconductor material show the highest response at 350 °C. Gas sensitivity tests indicated that α-MoO₃ nanobelts respond well to 50 ∼ 600 ppm ethanol at optimal operating temperatures. The selectivity test among various reducing gases shows that the sensor responds better to ethanol compared to other gases such as xylene, NO₂, CO, and H₂ gases. This excellent sensing performance is attributed to the unique sensing mechanism formed in the layered MoO₃ nanobelts through the catalytic reaction between ethanol and MoO₃ lattice oxygen and adsorbed oxygen. The sensing mechanism of the co-catalytic effect of lattice oxygen and adsorbed oxygen on ethanol is also discussed in depth.