Gas sensing performance of 2D nanomaterials/metal oxide nanocomposites: a review

In recent years, the utilization of gas sensors has increased tremendously in daily life and industry. Importantly, appropriate material selection should be made for gas sensors in order to achieve outstanding gas sensing performance, such as high sensitivity, good selectivity, a fast response/recovery time, and long-term stability. Numerous studies have shown that neither pure metal oxide semiconductor nor individual 2D nanomaterial (graphene, transition metal dichalcogenides, metal-organic frameworks, metal oxide nanosheets, MXenes, and phosphorene) based gas sensors are capable of showing excellent gas-sensing performance towards gas molecules. However, synergistic combinations of metal oxides and 2D nanomaterials have demonstrated enhanced gas-sensing performance in many studies. This review aims at providing a comprehensive summary of the current advancements in 2D/metal-oxide based heterostructures as gas sensors. Additionally, the underlying sensing mechanisms of various kinds of gas sensors are systematically described, and the device architectures and their corresponding sensing performances are summarized. Finally, the challenges and future prospects of 2D/metal-oxide nanocomposite-based gas sensors for sensing applications have been outlined.