Controllable assembly of SnO2 nanocubes onto TiO2 electrospun nanofibers toward humidity sensing applications

Abstract

One-dimensional SnO₂/TiO₂ heterostructures were successfully synthesized through the hydrothermal assembly of the single-crystalline SnO₂ nanocubes onto the TiO₂ electrospun nanofibers. The as-synthesized heterostructures with controllable coverage density of SnO₂ nanocubes were then coated onto the ceramic-based interdigital electrodes to produce the humidity nanosensors for the investigation of their humidity sensing characteristics. The results showed that the optimal nanosensor with ∼20 at% SnO₂-based heterostructure exhibited good humidity sensitivity, fast response–recovery behavior, low humidity hysteresis, and good reproducibility. In particular, the response and recovery times of this optimal nanosensor could reach ∼2.4 s and ∼30.2 s, respectively, which were considerably shorter than the corresponding values of TiO₂ nanofiber-based humidity nanosensors. The improved sensitivity characteristics for the SnO₂/TiO₂ heterostructures can be attributed to the interfacial electron transfer between SnO₂ nanocubes and TiO₂ nanofibers, which leads to an appropriate height of the potential barrier on the surface of the heterostructures for water adsorption and desorption. Our proposed humidity sensing mechanism would provide opportunities to guide the design and fabrication of other high-performance humidity sensors based on semiconductor heterostructures.