Porous wide band gap BiNbO4 ceramic nanopowder synthesised by low temperature solution-based method for gas sensing applications

Abstract

In this study, we report the gas sensing behavior of BiNbO₄ nanopowder prepared by a low temperature simple solution-based method. Before the sensing behaviour study, the as-synthesized nanopowder was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-diffuse reflectance spectroscopy, impedance analysis, and surface area measurement. The NH₃ sensing behavior of BiNbO₄ was then studied by temperature modulation (50–350 °C) as well as concentration modulation (20–140 ppm). At the optimum operating temperature of 325 °C, the sensitivity was measured to be 90%. The cross-sensitivity of as-synthesized BiNbO₄ sensor was also investigated by assessing the sensing behavior toward other gases such as hydrogen sulphide (H₂S), ethanol (C₂H₅OH), and liquid petroleum gas (LPG). Finally, selectivity of the sensing material toward NH₃ was characterized by observing the sensor response with gas concentrations in the range 20–140 ppm. The response and recovery time for NH₃ sensing at 120 ppm were about 16 s and about 17 s, respectively.