Modulation of ZnFe2O4/ZnO heterostructure for enhanced triethylamine sensing performance

The emerging in-plane heterostructures exhibit unique structure properties, attracting considerable attention in the gas sensors. However, the insight of the structure difference between in-plane and out-plane heterojunctions as well as the structure-activity relationship are still ambiguous. Herein, a novel in-plane ZnFe2O4/ZnO heterojunction (ZnFe2O4/ZnO-1) is designed for the efficient detection of triethylamine, which exhibits superior sensing performance with high selectivity and fast response/recovery, and the sensing response (Ra/Rg=424.07, 50 ppm) is 3.66 folds higher than the out-plane ZnFe2O4/ZnO heterojunction (ZnFe2O4/ZnO-2). Moreover, multiple structure analysis and DFT calculations reveal numerous grain boundaries form in ZnFe2O4/ZnO-1, and the lattice strain, d-band electronic structure, surface oxygen species as well as the surface acidity exhibit great difference with ZnFe2O4/ZnO-2. Notably, the formation of in-plane heterojunctions facilitates the generation of abundant surface O2- (ad) species and large amounts of Lewis acid sites, as well as the upshift of d-band center, which contributes to the enhanced triethylamine sensing performance. Our work illustrates the structure-activity relationship between in-plane and out-plane heterojunctions, and paves the way for the design of novel heterostructure for detecting harmful volatile organic compounds.