MoS<inf>2</inf>-PVP Nanocomposites Decorated ZnO Microsheets for Efficient Hydrogen Detection

Over the past several decades, metal oxide based gas sensors are widely used for hydrogen gas sensing applications. However, their poor sensitivity and very high value of operating temperature (> 300 °C) pose a severe threat over hydrogen detection due to its highly flammable nature. In recent years, a few strategies have been explored by the researchers to address these formidable challenges faced by the sensing technology. Here, we present MoS2/ZnO hybrid exhibiting higher molecular detection at low operating temperature. The ZnO film was grown using the magnetron sputtering technique, while MoS2-PVP nanocomposites (MoS2-PVP NCs) were synthesized through organic polymer assisted liquid exfoliation process. We examined the sensing performance of various MoS2/ZnO hybrids prepared by the decoration of different concentration MoS2-PVP NCs over the ZnO surface. The decoration of ZnO film through MoS2-PVP NCs increases the effective surface area and the number of active sites for the hydrogen molecules to get adsorbed, hence improved the surface reactivity to gas molecules. Interestingly, a 5 mg/mL MoS2-PVP NCs decorated ZnO sensor showed an improvement of $\sim 8$ times in sensing response as compared to the pristine ZnO based sensor upon 50 ppm hydrogen exposure. The improvement in sensing ability is primarily ascribed to electronic sensitization and spillover effects. Our results establish that the MoS2/ZnO hybrid exhibit superior hydrogen sensing behavior indicating the prominent role of MoS2-PVP NCs in hydrogen detection.