High-performance humidity sensor based on Ag-doped ZnGa2O4/ZnO composite nanofibers

Abstract

Ag-doped ZnGa₂O₄/ZnO composite nanofibers (ZG-Ag) were synthesized using electrostatic spinning followed by calcination. Compared to undoped ZnGa₂O₄/ZnO composite nanofibers (ZG), Ag-doped ZnGa₂O₄/ZnO composite variants exhibited superior room-temperature humidity sensing capabilities. Notably, the humidity-sensitive performance of the Ag-doped ZnGa₂O₄/ZnO composite nanofibers can be tuned by adjusting the Ag content, achieving a reliable wet hysteresis of 2.81% and a rapid response and recovery time of 1.5 and 2 seconds, respectively. The humidity sensing mechanism of the composites was also investigated. Compounding ZnO with ZnGa₂O₄ was found to mitigate the hysteresis issue, while the porous nanofiber structure and doping with Ag increased oxygen vacancies and conductivity. These enhancements collectively contributed to an improved sensitivity to water molecules.