Engineering of Mesoporous Cube-like InO Products as Ethanol Detection Platform at Low Operating Temperature: Effects of Different Transition Metals as Dopant Ions.

Although most semiconductor metal oxides including InO show acceptable sensitivity to volatile organic compounds, it is difficult to detect ethanol effectively at low operating temperatures and detection levels. In this study, pure and Co-, Ni-, and Cu-doped InO products with their doping content maintained at 1 mol % were successfully produced using a hydrothermal approach. Explicit contrast on the structural, microstructural, and textural properties of the synthesized InO products was examined to determine their gas sensing performance. The Cu-doped InO sensor demonstrated improved response of 15.3 to 50 ppm ethanol and has satisfactory selectivity, stability, low detection limit of 0.2, humidity resistance, and decreased working temperature of 80 °C compared to 150 °C of the pure InO sensor. This optimal gas sensing performance is derived from the cube-like morphology assembled with interlinked nanoparticles, which favors trapping more target gas molecules and exposing more active sites, thereby greatly improving its sensing ability. This study showed that the Cu-doped InO sensor with 1 mol % is suitable for monitoring ethanol gas for food safety applications.