Tuning doping and surface functionalization of columnar oxide films for volatile organic compound sensing: experiments and theory

Abstract

In this work, a new strategy based on the surface functionalization and doping of semiconducting oxides was proposed for tuning device properties. A considerable increase in the gas sensing ability of Fe-doped ZnO (ZnO:Fe) columnar films grown by chemical deposition is achieved via surface decoration with oxidized silver nanoparticles (AgO/Ag NPs) with a diameter of ~7-10 nm. AgO/Ag-decorated ZnO:Fe (Ag/ZnO:Fe) samples showed an optimal operating temperature of 300 0C with fast recovery of the signal (~ 7 s) and ultra-high sensitivity to ethanol vapor versus CH4 and H2 gases. The results presented demonstrate the potential for a significant increase in sensitivity to ethanol vapors by surface decoration with AgO/Ag NPs (density of ~ 0.8 × 109 cm-2) while maintaining extremely high selectivity.