Pt-decorated zinc oxide nanorod arrays with graphitic carbon nitride nanosheets for highly efficient dual-functional gas sensing.

In this work, well-aligned ZnO nanorods were grown on the substrate of exfoliated g-CN nanosheets via a microwave-assisted hydrothermal synthesis, and then Pt/ZnO/g-CN nanostructures were obtained after the deposition of Pt nanoparticles. The growth of vertically ordered ZnO nanorods was occurred on g-CN nanosheets through the bonding interaction between Zn and N atoms, which was confirmed by XPS, FT-IR data and molecular orbital theory. The Pt/ZnO/g-CN nanostructures sensor exhibited the remarkable sensitivity, selectivity, and fast response/recovery time for air pollutants of ethanol and NO. The application of Pt/ZnO/g-CN nanostructures could be used as a dual-functional gas sensor through the controlled working temperature. Besides, the Pt/ZnO/g-CN nanostructures sensor could be applied to the repeating detection of ethanol and NO in the natural environment. The synergistic effect and improved the separation of electron-hole pairs in Pt/ZnO/g-CN nanostructures had been verified for the gas sensing mechanism. Additionally, Pt/ZnO/g-CN nanostructures revealed the excellent charge carriers transport properties in electrochemical impedance spectroscopy (EIS), such as the longer electron lifetime (τ), higher electron diffusion coefficient (D) and bigger effective diffusion length (L), which also played an important role for Pt/ZnO/g-CN nanostructures with striking gas sensing activities.