Design of highly sensitive and selective ethanol sensor based on α -Fe ₂ O ₃ /Nb ₂ O ₅ heterostructure

Abstract

Abstract The introduction of heterostructures is a new approach in gas sensing due to their easy and quick transport of charges. Herein, facile hydrothermal and solid-state techniques are employed to synthesize an α -Fe 2 O 3 /Nb 2 O 5 heterostructure. The morphology, microstructure, crystallinity and surface composition of the synthesized heterostructures are investigated by scanning electron microscope, transmission electron microscope, x-ray diffraction, x-ray photoelectron spectroscopy and Brunauer–Emmett–Teller analyses. The successful fabrication of the heterostructures was achieved via the mutual incorporation of α -Fe 2 O 3 nanorods with Nb 2 O 5 interconnected nanoparticles (INPs). A sensor based on the α -Fe 2 O 3 (0.09)/Nb 2 O 5 heterostructure with a high surface area exhibited enhanced gas-sensing features, maintaining high selectivity and sensitivity, and a considerable recovery percentage towards ethanol gas. The sensing response of the α -Fe 2 O 3 (0.09)/Nb 2 O 5 heterostructure at lower operating temperature (160 °C) is around nine times higher than a pure Nb 2 O 5 (INP) sensor at 180 °C with the flow of 100 ppm ethanol gas. The sensors also show excellent selectivity, good long-term stability and a rapid response/recovery time (8s/2s, respectively) to ethanol. The superior electronic conductivity and upgraded sensitivity performance of gas sensors based on the α -Fe 2 O 3 (0.09)/Nb 2 O 5 heterostructure are attributed due to its unique structural features, high specific surface area and the synergic effect of the n–n heterojunction. The promising results demonstrate the potential application of the α -Fe 2 O 3 (0.09)/Nb 2 O 5 heterostructure as a good sensing material for the fabrication of ethanol sensors.