High-sensitive NO2 sensor based on p-NiCo2O4/n-WO3 heterojunctions

Abstract

In this paper, a NO2 gas sensor with outstanding sensing performance based on NiCo2O4/WO3 nanocomposite was synthesized by a hydrothermal method. A variety of testing methods such as XRD, SEM, TEM and XPS were applied to characterize the microstructure, morphology and element compositions of the sensing material. The sensing properties of NiCo2O4/WO3 composite films to NO2 gas were studied at the optimal temperature of 150 oC. The test results of gas sensor showed that, compared with the pristine WO3 sensor, the NiCo2O4/WO3 composite film sensor had higher response (116.9@20 ppm), shorter response/recovery time (13 s/16 s@20 ppm), good linearity, stable repeatability and brilliant selectivity. The enhanced gas sensitivity of NiCo2O4/WO3 nanocomposite films may be due to the synergistic effect of the unique microstructure of NiCo2O4/WO3 and the p-n heterojunction formed between the two materials.