Fabrication of polypyrrole/Zn2SnO4 nanofilm for ultra-highly sensitive ammonia sensing application

This paper demonstrates an ultra-highly sensitive ammonia gas sensor based on polypyrrole/zinc stannate (PPy/Zn2SnO4) nanocomposite. The PPy/Zn2SnO4 nanocomposite was synthesized by layer-by-layer alternative deposition of PPy nanospheres and Zn2SnO4 hollow spheres. The as-prepared sample was characterized by X-ray diffraction (XRD), FT-IR spectrums, scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM). The gas-sensing properties of the PPy/Zn2SnO4 nanofilm were investigated upon exposure to ammonia gas. The result showed that the PPy/Zn2SnO4 nanofilm sensor exhibited lower detection limit, higher response, faster response/recovery time, outstanding repeatability toward NH3 gas, which was greatly superior to the pure PPy and Zn2SnO4 counterparts. Such dramatically enhancement of gas-sensing properties for PPy/Zn2SnO4 nanofilm is attributed to the deprotonation/protonation process of ammonia adsorption/desorption on PPy surface, special interactions at p-n heterojunction, and high surface area of PPy/Zn2SnO4 nanocomposite.