Self-template-derived ZnCo2O4 porous microspheres decorated by Ag nanoparticles and their selective detection of formaldehyde

Abstract

ZnCo₂O₄ porous microspheres were successfully synthesized through a facile one-step solvent method using polyethylene glycol 1000 as a self-assembly template and subsequent annealing. Ag particles were then grown on their surface via a green and facile precipitation process. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The gas sensing properties of ZnCo₂O₄ and Ag–ZnCo₂O₄ were investigated at their optimum operating temperatures (99.3 and 119.1 °C), respectively. The results show that the response of Ag–ZnCo₂O₄ (11.18) is much higher than that of pure ZnCo₂O₄ materials (4.5) to 100 ppm formaldehyde at their optimum operating temperature. Meanwhile, compared to ZnCo₂O₄, the Ag–ZnCo₂O₄-based gas sensor exhibits excellent selectivity to formaldehyde over acetone, xylene, toluene, carbinol, alcohol and benzene. The results indicate that the modification via Ag particles can improve the gas sensing properties of the ZnCo₂O₄ hollow microspheres.