Novel nanosynthesis of In₂O₃ and its application as a resistive gas sensor for sevoflurane anesthetic

A novel non-aqueous sol-gel route for synthesizing pure indium oxide (In₂O₃) nanoparticles (NPs) using indium acetylacetonate and n-butylamine as the reactive solvent, under solvothermal conditions, is herein proposed. The samples were characterized by an advanced X-ray method, whole powder pattern modeling (WPPM) and high-resolution transmission electron microscopy (HR-TEM), showing the exclusive presence of pure In₂O₃. Diffuse reflectance spectroscopy (DRS) was used to determine the optical band gap (E_g) of the sample. Moreover, these investigations also revealed that the In₂O₃ nanoparticles are quasi-spherical in shape, with a diameter of around 7 nm as prepared and 9.5 nm after thermal treatment at 250 °C. In₂O₃ NPs worked as highly sensitive sensing interfaces to provide resistance changes during exposure to sevoflurane, a volatile anesthetic agent used in surgical wards. The developed sensor demonstrated a good response and fast response/recovery time towards very low concentrations of sevoflurane in air, suggesting a very attractive application as a real-time monitoring analyzer in a hospital environment.