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

Abstract

In this work, well-aligned ZnO nanorods were grown on the substrate of exfoliated g-C₃N₄ nanosheets via a microwave-assisted hydrothermal synthesis, and then Pt/ZnO/g-C₃N₄ nanostructures were obtained after the deposition of Pt nanoparticles. The growth of vertically ordered ZnO nanorods was occurred on g-C₃N₄ 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-C₃N₄ nanostructures sensor exhibited the remarkable sensitivity, selectivity, and fast response/recovery time for air pollutants of ethanol and NO₂. The application of Pt/ZnO/g-C₃N₄ nanostructures could be used as a dual-functional gas sensor through the controlled working temperature. Besides, the Pt/ZnO/g-C₃N₄ nanostructures sensor could be applied to the repeating detection of ethanol and NO₂ in the natural environment. The synergistic effect and improved the separation of electron-hole pairs in Pt/ZnO/g-C₃N₄ nanostructures had been verified for the gas sensing mechanism. Additionally, Pt/ZnO/g-C₃N₄ nanostructures revealed the excellent charge carriers transport properties in electrochemical impedance spectroscopy (EIS), such as the longer electron lifetime (τ_n), higher electron diffusion coefficient (D_n) and bigger effective diffusion length (L_n), which also played an important role for Pt/ZnO/g-C₃N₄ nanostructures with striking gas sensing activities.

Keywords: Gas sensor; Graphitic carbon nitride; Heterostructure; Synergistic effect; Zinc oxide.