Insight into metallic oxide semiconductor (SnO2, ZnO, CuO, α-Fe2O3, WO3)-carbon nitride (g-C3N4) heterojunction for gas sensing application

The composition of gas or air mixture in a particular gas sensing environment greatly influences the properties, such as surface conductivity of metallic oxide-based gas sensors. In the recent years many native metallic oxide gas sensors, for instance, CuO, ZnO, SnO2, WO3, and α-Fe3O4 have been extensively exploited for their selectivity and sensing abilities towards different gases. Most of the researches has been conducted recently and is focused on addition of variety of dopants, mostly metal based oxide semiconductors-based gas sensors. A 2-dimensional graphitic carbon nitride g-C3N4 (GCN) is a novel metal-free catalyst comprising of carbon and nitrogen, which is exploited extensively in many gas sensing applications, owing to its excellent chemical stability and substrate characteristics. Various metal oxide semiconductors based heterojunction can be constructed with GCN. The enhanced gas sensing properties are related to the heterojunctions of GCN nanosheets made with semiconductors. The present review aim to shed a further light on the designing and construction of heterojunctional structures based on adding metal oxide nanostructures with GCN for improved gas sensing capabilities.