Facile synthesis of ZnFe2O4/α-Fe2O3 porous microrods with enhanced TEA-sensing performance

Developing metal oxide nanocomposite with superior gas-sensing properties is an important subject in the field of gas sensor. In this paper, we reported a facile synthesis route for ZnFe2O4/α-Fe2O3 porous microrods (PMRs) by using dual oxalates as sacrificial template. FeC2O4·2H2O solid microrods (SMRs) were first synthesized by a chemical precipitation reaction between FeSO4·7H2O and H2C2O4·2H2O, which were then immersed in Zn2+ aqueous solution to obtain the hybrid ZnC2O4·2H2O/FeC2O4·2H2O SMRs through the substitution reaction between Zn2+ and Fe2+. After a proper annealing process, ZnFe2O4/α-Fe2O3 PMRs were successfully prepared through the decomposition of ZnC2O4·2H2O/FeC2O4·2H2O SMRs. The prepared ZnFe2O4/α-Fe2O3 PMRs are about 2-5 μm in length and 0.3-0.5 μm in diameter, and constructed by numerous loosely stacked nanoparticles with the size about 15 nm. The dominant pore size in ZnFe2O4/α-Fe2O3 PMRs is around 10 nm. The results of gas-sensing tests indicates that through decorating the α-Fe2O3PMRs with ZnFe2O4, the response of the sensor towards TEA is remarkably improved. For example, the response of the composite sensor to 100 ppm TEA is as high as 42.4, which is about 20 times higher than that of the bare α-Fe2O3 PMRs sensor (2.5). The enhanced TEA sensing mechanism of ZnFe2O4/α-Fe2O3 PMRs was discussed in detail.