Co3O4/ZnO nanocomposites for gas-sensing applications

Co3O4/ZnO nanocomposites were prepared by an easy wet-chemistry route without any organic additive or surfactant used. The nanocomposites were systematically characterized by X-ray powder diffraction, scanning electron microscopy, (high-resolution) transmission electron microscopy, selected area electron diffraction, and energy-dispersive X-ray spectroscopy. The results show that ZnO is loaded on the surface of Co3O4 nanoparticles with a compact and clean hetero-interface. The obtained nanocomposites were tested for gas-sensing applications with ethanol and formaldehyde as model gases. It was revealed that the nanocomposites exhibit enhanced gas-sensing performance such as high stability and high sensing response. The sensing responses to 100 ppm ethanol or formaldehyde (46 to ethanol and 20 to formaldehyde) are much higher than those of pristine Co3O4 nanoparticles (6.2 to ethanol and 4.4 to formaldehyde), commercial Co3O4 powder (1.6 to ethanol and 1.5 to formaldehyde), and pure ZnO sample (7.5 to ethanol and 4.1 to formaldehyde). These results suggest that the integration of Co3O4 with ZnO is a promising route to the development of effective sensing materials. The excellent gas-sensing properties and the easily up-scalable preparation route make the prepared nanocomposites be promising for real applications.