Enhanced acetic acid sensing of MOF-derived alpha-Fe2O3/ZrO2 arising from phase junction and defects

Monitoring acetic acid as a volatile organic compound, which is a key source of pollution, using metal oxides has a great demand and advantage in evaluating air quality. Herein, we present a facile route to modulate the alpha-Fe2O3/ZrO2 heterojunction for the detection of acetic acid, derived from the pyrolyzation of a zirconium-ferrocene metal-organic framework as the sacrificial precursor, coupled with reduced graphene oxide as the template. Resultantly, the alpha-Fe2O3/ZrO2 heterojunction exhibits a significant response with a maximum response of 61.5 to 100 ppm acetic acid at 225 degrees C, exceeding that of the Fe/Zr-0, in the top group of similar sensors. Furthermore, the sensing mechanism is elaborately investigated by X-ray photoelectron, photoluminescence, and Raman spectroscopy and theoretical calculations, possibly resulting from the coexistence of the heterojunction, phase junction and defects, which can accelerate the carrier transfer at the interface and maximize the adsorption of oxygen ions. This work presents a novel combinatorial strategy that opens up a possibility for improving the performance of gas sensors.