Hierarchical core-shell heterostructures of α-MoO3 nanorods@NiO nanosheets for significant detection of ethyl acetate vapor

Abstract

Ethyl acetate (EA), can be served as an important marker to evaluate the freshness of many fruits. However, it is still a limiting factor to efficiently detect it due to the low chemical reactivity and complex interferences. Herein, a hierarchical one-dimenstional (1D) heterostructure consisting of the α-MoO3 nanorods (core) and NiO nanosheets (shell) has been successfully demonstrated by a facile hydrothermal and followed annealing route. This hierarchical core-shell heterojuction integrates the structural merits and synergistic catalytic activity of two transition metal oxide (α-MoO3 and NiO). As an outcome, this α-MoO3 @NiO product shows a significant response towards EA vapor in terms of high response, impressive selectivity, and low detection limit (~148 ppb). Moreover, the in-situ DRIFTS results reveal the possible intermediates (acetyl and acetate) in this EA-sensing event. Meanwhile, the enhancement in EA-sensing is also discussed from the aspects of strong adsorption of EA molecules onto the surfaces, n-p heterojunction between the α-MoO3 nanorods and NiO nanosheets, as well as increase of specific surface area and surface chemisorbed oxygen. This work sheds a new hierarchical core-shell heterojuction for detection of low reactive vapor in complex surroundings.