On improved inorganic gas-sensing characteristics of microwave-treated tungsten oxide quantum dots at room temperature

Abstract

Tungsten oxide (WO₃) based metal oxide semiconductor material has been conventionally used for sensing inorganic gases at elevated temperatures. However, in this study, the gas sensing performance of tungsten oxide-based sensors is evaluated at room temperature. In this study, WO₃ quantum dots (QDs) are synthesized via the electrochemical method, followed by a microwave treatment to dehydrate them. The newly developed process is relatively less expensive and offers the flexibility to alter the structure in terms of phase, size, shape, and vacancy concentration. It is observed that electrochemical process parameters play an important role in phase evolution and control the oxygen vacancy concentration in the powder, which are essential for enhancing its gas sensing characteristics. Results showed an enhanced gas-sensing ability of WO₃ QDs at room temperature toward inorganic gases, such as CO, NO₂, NH₃, and H₂ when subjected to microwave treatment. The enhanced gas-sensing performance of microwave-treated WO₃ QDs is attributed to its smaller size and high oxygen vacancy concentration. The minimum limit of detection values for CO, NO₂, NH₃, and H₂ at room temperature using microwave-treated hydrated tungsten oxide QDs were 4.60, 1.5, 0.35, and 10.25 ppm, respectively.