Morphological alterations in WO3-SnO2 heterostructures and their effects on chlorine sensing

Heterostructured WO3-SnO2 nanoarchitects as a promising candidate for reliable chlorine (Cl2) gas monitoring with a limit of detection (LoD) as low as 9 ppb are demonstrated. The sensing characteristics of the active layer in the form of n-WO3 thin sheets decorated with n-SnO2 nanoparticles were investigated by comparing with control samples (pure SnO2 and WO3), thus validating the dependency of sensitivity on the crystal structure and n-n nanointerfaces. The WO3-SnO2 heterostructure in the equimole ratio, when compared to individual WO3 and SnO2 microsensors, showcased ultrasensitivity (a 3 and 9-fold enhancement, respectively), superior selectivity (in presence of 12 gases), excellent long term stability (20 days), minimum CoV (0.006%) with response kinetics (τRes=374 s and τRec=1016 s) at a low operating temperature of 100 oC. The enhanced performance depicted here by the n-n heterostructured microsensor is foreseen to make it highly suitable for applications requiring low ppm Cl2 detection in a dry and humid environment.