Improved TEA sensing performance of ZnCo2O4 by structure evolution from porous nanorod to single-layer nanochain

Improving the gas sensing performance of metal oxide semiconductor (MOS) by structural modification has attracted intensive interest in the field of gas sensor. In this work, two kinds of ZnCo2O4 nanostructures, including porous nanorod (PNR) and single-layer nanochain (SLNC), were prepared by annealing pre-synthesized ZnC2O4/CoC2O4 hybrid nanorods at different temperatures. The ZnCo2O4 PNRs obtained at 350 degrees C were constructed by numerous densely stacked nanoparticles with the size about 7 nm. While, the ZnCo2O4 SLNCs obtained at 500 degrees C featured an assembly of nanoparticles with the size about 20 nm, and along the diameter direction there is only one layer of nanoparticles. It was found that through the structure evolution from PNR to SLNC, the specific surface area of the synthesized ZnCo2O4 was decreased from 91.6 m(2)/g (ZCO-350) to 24.7 m(2)/g (ZCO-500). However, the results of gas sensing tests indicated that the sensor fabricated with ZnCo2O4 SLNC showed an remarkable improvement of TEA sensing performance as compared with that fabricated with ZnCo2O4 PNR, especially in terms of response value and response/recover speed. Such abnormal relationship between specific surface area and gas sensing performance was attributed to the higher available surface area of ZnCo2O4 SLNC.