Optimisation of H‐doped WO₃ synthesis at ambient conditions for potential acetone gas sensing

Abstract

Tungsten trioxide (WO3) is a highly desired semiconductor metal oxide (SMO) to detect acetone gas which is present at high levels in the breath of diabetic patients. Current research in the biosensor field is focused on the synthesis of sensing material at room temperature to ease fabrication and reduce energy requirements for operations. In this context, hydrogen doping aids in increasing the baseline conductivity of WO3. Therefore, the current research aimed to synthesise H‐doped WO3 at ambient conditions via an ultrasonication‐assisted hydrogenation route. Besides, the independent effects of other factors on hydrogenation were studied. These include synthesis temperature (room temperature to 80°C) and zinc precursor loading (0.8 to 2.0). By varying the concentrations of WO3 for the synthesis, it was determined that the highest degree of hydrogenation was achieved at 10 mg/ml. This was indicated by a visible colour change to dark blue and the highest conductivity. The findings revealed that hydrogenation is less effective at higher temperatures. The most optimum zinc loading was found to be 1.6 where the maximum attainable conductivity was 116.1 mS/cm. This H‐doped WO3 sample was subsequently subjected to diluted acetone sensing performance. The sample showed a significant reduction in resistance towards diluted acetone of 1000 ppm compared to undoped WO3. Thus, findings from this work offer a potential room temperature‐based synthesis method for acetone detection at low concentration.