A facile cotton biotemplate to fabricate porous ZnFe2O4 sheets for acetone gas sensing application

Developing methods to synthesize semiconductor oxides with hierarchically porous architecture is an effective way to improve their sensing properties. Herein, a strategy using cotton as biotemplates involving immersion, solvothermal reaction and calcination has been developed to synthesize ZnFe2O4 with porous flaky and curly sheets structure. The calcination temperature was optimized, and sensing properties of the as-prepared porous ZnFe2O4 sheet composites were investigated. For comparison, without cotton template, ZnFe2O4 nanoparticle (NPs) was synthesized. Meanwhile, without solvothermal reaction, ZnFe2O4 mixture of fiber-like structure and NPs (ZnFe2O4 fiber/NPs) was obtained. Sensors based on these comparison samples showed poor sensing performance to various gases. Whereas, the sensor based on porous ZnFe2O4 sheet composite calcined at 600 ℃ exhibited good selectivity, fast response and stability to acetone, and a high response of 66.7–100 ppm was also obtained at 220 ℃. The good sensing performance of the porous ZnFe2O4 sheet composite was mainly attributed to its porous structure and the formation of heterojunctions with ZnO and Fe2O3 found in the composite. The strategy might also be an effective way to fabricate other porous nanomaterials for applications besides ZnFe2O4.