Fig. 2From: Improved recovery of NO2 sensors using heterojunctions between transition metal dichalcogenides and ZnO nanoparticlesScanning electron microscopic images of a MoS2-, b MoS2/ZnO-, c WSe2-, d WSe2/ZnO-based gas sensors. The red arrow represents the ZnO nanoparticles (NP). The insets in b and d show SEM image of undiluted ZnO nanoparticles. The scale bars in the insets are 250 nmBack to article page