Synthesis of randomly oriented self-assembled WO3 and WO3-WS2 nanoplates for selective oxygen sensing

In this paper, the development of two-dimensional metal dichalcogenide WO3-WS2 nanoplates for highly selective oxygen sensing application was reported. A facile precipitation method to produce self-assembled WO3 nanoplates and one-step solid-state synthesis of self-assembled WO3-WS2 nanoplates was described. X-ray diffraction (XRD) confirms the formation of WO3 and WO3-WS2 hybrid structure. The as-synthesized nanoplates were investigated for sensing applications of ethanol, methanol, n-butanol, LPG, and O-2 gas. Study revealed that both as-synthesized WO3 and WO3-WS2 nanoplate sensors are highly selective for oxygen sensing application. Response percentage of WO3 nanoplates and WO3-WS2 nanoplates measured at 500-ppm oxygen concentration was 40% and 95% respectively. The measured response time and recovery times of WO3-WS2 nanoplate sensor was shorter than WO3 nanoplate sensor at all concentrations. The improved performance of as-synthesized WO3-WS2 nanoplates was attributed to the formation of deeper depletion layer between WS2 and WO3 p-n junction which provide additional adsorption sites for oxygen species.