Unusual properties of nanostructured Ce1−xCoxO2−y, Ce1−xNixO2−y and Ce1−(x+y)CoxNiyO2−z: structural studies and catalytic activity

Abstract

In this paper, a series of nanostructured CeO2 spheres with two different dopants, Co2+ and Ni2+, were synthesized by a one-step hydrothermal synthesis free from the template-assisted calcination, and were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICP-MS) and nitrogen adsorption–desorption measurements. The formation process of the produced spheres involved Ostwald ripening, secondary nucleation and oriented attachment. Both the presence of Co2+, Ni2+ and the interaction of Ce4+/Ce3+ with dopants promoted the production of oxygen vacancies, which explained the result that the catalytic performance in CO oxidation of CeO2 with both dopants was better than that with single dopant, and that with single dopant held much advantage towards pure CeO2.