Well-crystallized ZnCo₂O₄ nanosheets as a new-style support of Au catalyst for high efficient CO preferential oxidation in H₂ stream under visible light irradiation

Highlights: • Spinel ZnCo₂O₄ nanosheets were fabricated by a facile template-free wet chemical method. • ZnCo₂O₄ nanosheet supported Au catalyst exhibited a good stability for oxidizing CO. • Visible light could promote the adsorption and activation of CO and O₂ on Au/ZnCo₂O₄. • A efficient charge transfer occurred on the interface of Au and ZnCo₂O₄. - Abstract: A kind of high dispersed gold catalyst supported on the spinel ZnCo₂O₄ nanosheets was readily fabricated by a facile template-free wet chemical method for CO oxidation in H₂-rich streams at room temperature under visible light irradiation or not, which was found to be a high performance catalyst. As verified by X-ray powder diffractometry (XRD), Raman spectra, N₂ adsorption–desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscope (XPS), photoelectrochemical measurement and photoluminescence (PL) spectra results, the contribution of high crystallinity, the enhanced mass and charge transport, the longer lifetime of surface electrons as well as the optical absorbance properties on Au/ZnCo₂O₄ enabled the superior CO preferential oxidation. Notably, electron paramagnetic resonance (EPR) and CO chemisorption (TPD-MS) results indicate that visible light could promote the adsorption and activation of both CO and O₂ at Au/ZnCo₂O₄ due to both the photo-response of Au nanoparticles and the photo-excitation of ZnCo₂O₄ band gap under visible light irradiation. This study indicates that Au/ZnCo₂O₄ may be highly desirable for a promising photo-assisted Au catalyst.